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3586 lines
149 KiB
VHDL
3586 lines
149 KiB
VHDL
-- Floating-point unit for Microwatt
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library ieee;
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use ieee.std_logic_1164.all;
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use ieee.numeric_std.all;
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library work;
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use work.insn_helpers.all;
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use work.decode_types.all;
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use work.crhelpers.all;
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use work.helpers.all;
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use work.common.all;
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entity fpu is
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port (
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clk : in std_ulogic;
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rst : in std_ulogic;
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flush_in : in std_ulogic;
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e_in : in Execute1ToFPUType;
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e_out : out FPUToExecute1Type;
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w_out : out FPUToWritebackType
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);
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end entity fpu;
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architecture behaviour of fpu is
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type fp_number_class is (ZERO, FINITE, INFINITY, NAN);
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constant EXP_BITS : natural := 13;
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constant UNIT_BIT : natural := 56;
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constant QNAN_BIT : natural := UNIT_BIT - 1;
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constant SP_LSB : natural := UNIT_BIT - 23;
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constant SP_GBIT : natural := SP_LSB - 1;
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constant SP_RBIT : natural := SP_LSB - 2;
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constant DP_LSB : natural := UNIT_BIT - 52;
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constant DP_GBIT : natural := DP_LSB - 1;
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constant DP_RBIT : natural := DP_LSB - 2;
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type fpu_reg_type is record
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class : fp_number_class;
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negative : std_ulogic;
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denorm : std_ulogic;
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exponent : signed(EXP_BITS-1 downto 0); -- unbiased
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mantissa : std_ulogic_vector(63 downto 0); -- 8.56 format
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end record;
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type state_t is (IDLE, DO_ILLEGAL,
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DO_MCRFS, DO_MTFSB, DO_MTFSFI, DO_MFFS, DO_MTFSF,
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DO_FMR, DO_FMRG, DO_FCMP, DO_FTDIV, DO_FTSQRT,
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DO_FCFID, DO_FCTI,
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DO_FRSP, DO_FRI,
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DO_FADD, DO_FMUL, DO_FDIV, DO_FSQRT, DO_FMADD,
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DO_FRE, DO_FRSQRTE,
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DO_FSEL,
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DO_IDIVMOD,
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FRI_1,
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ADD_1, ADD_SHIFT, ADD_2, ADD_3,
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CMP_1, CMP_2,
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MULT_1,
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FMADD_0, FMADD_1, FMADD_2, FMADD_3,
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FMADD_4, FMADD_5, FMADD_6,
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LOOKUP,
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DIV_2, DIV_3, DIV_4, DIV_5, DIV_6,
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FRE_1,
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RSQRT_1,
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FTDIV_1,
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SQRT_1, SQRT_2, SQRT_3, SQRT_4,
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SQRT_5, SQRT_6, SQRT_7, SQRT_8,
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SQRT_9, SQRT_10, SQRT_11, SQRT_12,
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INT_SHIFT, INT_ROUND, INT_ISHIFT,
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INT_FINAL, INT_CHECK, INT_OFLOW,
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FINISH, NORMALIZE,
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ROUND_UFLOW, ROUND_OFLOW,
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ROUNDING, ROUNDING_2, ROUNDING_3,
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DENORM,
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RENORM_A, RENORM_A2,
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RENORM_B, RENORM_B2,
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RENORM_C, RENORM_C2,
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NAN_RESULT, EXC_RESULT,
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IDIV_NORMB, IDIV_NORMB2, IDIV_NORMB3,
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IDIV_CLZA, IDIV_CLZA2, IDIV_CLZA3,
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IDIV_NR0, IDIV_NR1, IDIV_NR2, IDIV_USE0_5,
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IDIV_DODIV, IDIV_SH32,
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IDIV_DIV, IDIV_DIV2, IDIV_DIV3, IDIV_DIV4, IDIV_DIV5,
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IDIV_DIV6, IDIV_DIV7, IDIV_DIV8, IDIV_DIV9,
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IDIV_EXT_TBH, IDIV_EXT_TBH2, IDIV_EXT_TBH3,
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IDIV_EXT_TBH4, IDIV_EXT_TBH5,
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IDIV_EXTDIV, IDIV_EXTDIV1, IDIV_EXTDIV2, IDIV_EXTDIV3,
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IDIV_EXTDIV4, IDIV_EXTDIV5, IDIV_EXTDIV6,
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IDIV_MODADJ, IDIV_MODSUB, IDIV_DIVADJ, IDIV_OVFCHK, IDIV_DONE, IDIV_ZERO);
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type decode32 is array(0 to 31) of state_t;
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type decode8 is array(0 to 7) of state_t;
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type reg_type is record
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state : state_t;
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busy : std_ulogic;
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f2stall : std_ulogic;
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instr_done : std_ulogic;
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complete : std_ulogic;
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do_intr : std_ulogic;
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illegal : std_ulogic;
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op : insn_type_t;
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insn : std_ulogic_vector(31 downto 0);
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instr_tag : instr_tag_t;
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dest_fpr : gspr_index_t;
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fe_mode : std_ulogic;
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rc : std_ulogic;
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fp_rc : std_ulogic;
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is_cmp : std_ulogic;
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single_prec : std_ulogic;
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sp_result : std_ulogic;
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fpscr : std_ulogic_vector(31 downto 0);
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comm_fpscr : std_ulogic_vector(31 downto 0); -- committed FPSCR value
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a : fpu_reg_type;
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b : fpu_reg_type;
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c : fpu_reg_type;
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r : std_ulogic_vector(63 downto 0); -- 8.56 format
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s : std_ulogic_vector(55 downto 0); -- extended fraction
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x : std_ulogic;
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p : std_ulogic_vector(63 downto 0); -- 8.56 format
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y : std_ulogic_vector(63 downto 0); -- 8.56 format
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result_sign : std_ulogic;
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result_class : fp_number_class;
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result_exp : signed(EXP_BITS-1 downto 0);
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shift : signed(EXP_BITS-1 downto 0);
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writing_fpr : std_ulogic;
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write_reg : gspr_index_t;
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complete_tag : instr_tag_t;
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writing_cr : std_ulogic;
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writing_xer : std_ulogic;
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int_result : std_ulogic;
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cr_result : std_ulogic_vector(3 downto 0);
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cr_mask : std_ulogic_vector(7 downto 0);
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old_exc : std_ulogic_vector(4 downto 0);
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update_fprf : std_ulogic;
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quieten_nan : std_ulogic;
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nsnan_result : std_ulogic;
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tiny : std_ulogic;
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denorm : std_ulogic;
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round_mode : std_ulogic_vector(2 downto 0);
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is_subtract : std_ulogic;
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exp_cmp : std_ulogic;
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madd_cmp : std_ulogic;
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add_bsmall : std_ulogic;
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is_multiply : std_ulogic;
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is_sqrt : std_ulogic;
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first : std_ulogic;
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count : unsigned(1 downto 0);
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doing_ftdiv : std_ulogic_vector(1 downto 0);
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opsel_a : std_ulogic_vector(1 downto 0);
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use_a : std_ulogic;
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use_b : std_ulogic;
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use_c : std_ulogic;
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invalid : std_ulogic;
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negate : std_ulogic;
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longmask : std_ulogic;
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integer_op : std_ulogic;
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divext : std_ulogic;
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divmod : std_ulogic;
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is_signed : std_ulogic;
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int_ovf : std_ulogic;
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div_close : std_ulogic;
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inc_quot : std_ulogic;
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a_hi : std_ulogic_vector(7 downto 0);
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a_lo : std_ulogic_vector(55 downto 0);
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m32b : std_ulogic;
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oe : std_ulogic;
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xerc : xer_common_t;
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xerc_result : xer_common_t;
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res_negate : std_ulogic;
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res_subtract : std_ulogic;
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res_rmode : std_ulogic_vector(2 downto 0);
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end record;
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type lookup_table is array(0 to 1023) of std_ulogic_vector(17 downto 0);
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signal r, rin : reg_type;
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signal fp_result : std_ulogic_vector(63 downto 0);
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signal opsel_b : std_ulogic_vector(1 downto 0);
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signal opsel_r : std_ulogic_vector(1 downto 0);
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signal opsel_s : std_ulogic_vector(1 downto 0);
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signal opsel_ainv : std_ulogic;
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signal opsel_mask : std_ulogic;
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signal opsel_binv : std_ulogic;
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signal in_a : std_ulogic_vector(63 downto 0);
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signal in_b : std_ulogic_vector(63 downto 0);
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signal result : std_ulogic_vector(63 downto 0);
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signal carry_in : std_ulogic;
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signal lost_bits : std_ulogic;
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signal r_hi_nz : std_ulogic;
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signal r_lo_nz : std_ulogic;
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signal r_gt_1 : std_ulogic;
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signal s_nz : std_ulogic;
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signal misc_sel : std_ulogic_vector(3 downto 0);
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signal f_to_multiply : MultiplyInputType;
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signal multiply_to_f : MultiplyOutputType;
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signal msel_1 : std_ulogic_vector(1 downto 0);
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signal msel_2 : std_ulogic_vector(1 downto 0);
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signal msel_add : std_ulogic_vector(1 downto 0);
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signal msel_inv : std_ulogic;
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signal inverse_est : std_ulogic_vector(18 downto 0);
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-- opsel values
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constant AIN_R : std_ulogic_vector(1 downto 0) := "00";
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constant AIN_A : std_ulogic_vector(1 downto 0) := "01";
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constant AIN_B : std_ulogic_vector(1 downto 0) := "10";
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constant AIN_C : std_ulogic_vector(1 downto 0) := "11";
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constant BIN_ZERO : std_ulogic_vector(1 downto 0) := "00";
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constant BIN_R : std_ulogic_vector(1 downto 0) := "01";
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constant BIN_RND : std_ulogic_vector(1 downto 0) := "10";
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constant BIN_PS8 : std_ulogic_vector(1 downto 0) := "11";
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constant RES_SUM : std_ulogic_vector(1 downto 0) := "00";
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constant RES_SHIFT : std_ulogic_vector(1 downto 0) := "01";
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constant RES_MULT : std_ulogic_vector(1 downto 0) := "10";
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constant RES_MISC : std_ulogic_vector(1 downto 0) := "11";
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constant S_ZERO : std_ulogic_vector(1 downto 0) := "00";
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constant S_NEG : std_ulogic_vector(1 downto 0) := "01";
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constant S_SHIFT : std_ulogic_vector(1 downto 0) := "10";
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constant S_MULT : std_ulogic_vector(1 downto 0) := "11";
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-- msel values
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constant MUL1_A : std_ulogic_vector(1 downto 0) := "00";
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constant MUL1_B : std_ulogic_vector(1 downto 0) := "01";
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constant MUL1_Y : std_ulogic_vector(1 downto 0) := "10";
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constant MUL1_R : std_ulogic_vector(1 downto 0) := "11";
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constant MUL2_C : std_ulogic_vector(1 downto 0) := "00";
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constant MUL2_LUT : std_ulogic_vector(1 downto 0) := "01";
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constant MUL2_P : std_ulogic_vector(1 downto 0) := "10";
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constant MUL2_R : std_ulogic_vector(1 downto 0) := "11";
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constant MULADD_ZERO : std_ulogic_vector(1 downto 0) := "00";
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constant MULADD_CONST : std_ulogic_vector(1 downto 0) := "01";
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constant MULADD_A : std_ulogic_vector(1 downto 0) := "10";
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constant MULADD_RS : std_ulogic_vector(1 downto 0) := "11";
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-- control signals and values for exponent data path
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constant REXP1_ZERO : std_ulogic_vector(1 downto 0) := "00";
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constant REXP1_R : std_ulogic_vector(1 downto 0) := "01";
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constant REXP1_A : std_ulogic_vector(1 downto 0) := "10";
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constant REXP1_BHALF : std_ulogic_vector(1 downto 0) := "11";
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constant REXP2_CON : std_ulogic_vector(1 downto 0) := "00";
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constant REXP2_NE : std_ulogic_vector(1 downto 0) := "01";
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constant REXP2_C : std_ulogic_vector(1 downto 0) := "10";
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constant REXP2_B : std_ulogic_vector(1 downto 0) := "11";
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constant RECON2_ZERO : std_ulogic_vector(1 downto 0) := "00";
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constant RECON2_UNIT : std_ulogic_vector(1 downto 0) := "01";
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constant RECON2_BIAS : std_ulogic_vector(1 downto 0) := "10";
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constant RECON2_MAX : std_ulogic_vector(1 downto 0) := "11";
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signal re_sel1 : std_ulogic_vector(1 downto 0);
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signal re_sel2 : std_ulogic_vector(1 downto 0);
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signal re_con2 : std_ulogic_vector(1 downto 0);
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signal re_neg1 : std_ulogic;
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signal re_neg2 : std_ulogic;
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signal re_set_result : std_ulogic;
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constant RSH1_ZERO : std_ulogic_vector(1 downto 0) := "00";
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constant RSH1_B : std_ulogic_vector(1 downto 0) := "01";
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constant RSH1_NE : std_ulogic_vector(1 downto 0) := "10";
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constant RSH1_S : std_ulogic_vector(1 downto 0) := "11";
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constant RSH2_CON : std_ulogic := '0';
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constant RSH2_A : std_ulogic := '1';
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constant RSCON2_ZERO : std_ulogic_vector(3 downto 0) := "0000";
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constant RSCON2_1 : std_ulogic_vector(3 downto 0) := "0001";
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constant RSCON2_UNIT_52 : std_ulogic_vector(3 downto 0) := "0010";
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constant RSCON2_64_UNIT : std_ulogic_vector(3 downto 0) := "0011";
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constant RSCON2_32 : std_ulogic_vector(3 downto 0) := "0100";
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constant RSCON2_52 : std_ulogic_vector(3 downto 0) := "0101";
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constant RSCON2_UNIT : std_ulogic_vector(3 downto 0) := "0110";
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constant RSCON2_63 : std_ulogic_vector(3 downto 0) := "0111";
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constant RSCON2_64 : std_ulogic_vector(3 downto 0) := "1000";
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constant RSCON2_MINEXP : std_ulogic_vector(3 downto 0) := "1001";
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signal rs_sel1 : std_ulogic_vector(1 downto 0);
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signal rs_sel2 : std_ulogic;
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signal rs_con2 : std_ulogic_vector(3 downto 0);
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signal rs_neg1 : std_ulogic;
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signal rs_neg2 : std_ulogic;
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signal rs_norm : std_ulogic;
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constant arith_decode : decode32 := (
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-- indexed by bits 5..1 of opcode
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2#01000# => DO_FRI,
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2#01100# => DO_FRSP,
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2#01110# => DO_FCTI,
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2#01111# => DO_FCTI,
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2#10010# => DO_FDIV,
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2#10100# => DO_FADD,
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2#10101# => DO_FADD,
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2#10110# => DO_FSQRT,
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2#11000# => DO_FRE,
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2#11001# => DO_FMUL,
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2#11010# => DO_FRSQRTE,
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2#11100# => DO_FMADD,
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2#11101# => DO_FMADD,
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2#11110# => DO_FMADD,
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2#11111# => DO_FMADD,
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others => DO_ILLEGAL
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);
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constant cmp_decode : decode8 := (
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2#000# => DO_FCMP,
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2#001# => DO_FCMP,
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2#010# => DO_MCRFS,
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2#100# => DO_FTDIV,
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2#101# => DO_FTSQRT,
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others => DO_ILLEGAL
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);
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constant misc_decode : decode32 := (
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-- indexed by bits 10, 8, 4, 2, 1 of opcode
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2#00010# => DO_MTFSB,
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2#01010# => DO_MTFSFI,
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2#10010# => DO_FMRG,
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2#11010# => DO_FMRG,
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2#10011# => DO_MFFS,
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2#11011# => DO_MTFSF,
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2#10110# => DO_FCFID,
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2#11110# => DO_FCFID,
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others => DO_ILLEGAL
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);
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-- Inverse lookup table, indexed by the top 8 fraction bits
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-- The first 256 entries are the reciprocal (1/x) lookup table,
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-- and the remaining 768 entries are the reciprocal square root table.
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-- Output range is [0.5, 1) in 0.19 format, though the top
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-- bit isn't stored since it is always 1.
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-- Each output value is the inverse of the center of the input
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-- range for the value, i.e. entry 0 is 1 / (1 + 1/512),
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-- entry 1 is 1 / (1 + 3/512), etc.
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constant inverse_table : lookup_table := (
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-- 1/x lookup table
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-- Unit bit is assumed to be 1, so input range is [1, 2)
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18x"3fc01", 18x"3f411", 18x"3ec31", 18x"3e460", 18x"3dc9f", 18x"3d4ec", 18x"3cd49", 18x"3c5b5",
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18x"3be2f", 18x"3b6b8", 18x"3af4f", 18x"3a7f4", 18x"3a0a7", 18x"39968", 18x"39237", 18x"38b14",
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18x"383fe", 18x"37cf5", 18x"375f9", 18x"36f0a", 18x"36828", 18x"36153", 18x"35a8a", 18x"353ce",
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18x"34d1e", 18x"3467a", 18x"33fe3", 18x"33957", 18x"332d7", 18x"32c62", 18x"325f9", 18x"31f9c",
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18x"3194a", 18x"31303", 18x"30cc7", 18x"30696", 18x"30070", 18x"2fa54", 18x"2f443", 18x"2ee3d",
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18x"2e841", 18x"2e250", 18x"2dc68", 18x"2d68b", 18x"2d0b8", 18x"2caee", 18x"2c52e", 18x"2bf79",
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18x"2b9cc", 18x"2b429", 18x"2ae90", 18x"2a900", 18x"2a379", 18x"29dfb", 18x"29887", 18x"2931b",
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18x"28db8", 18x"2885e", 18x"2830d", 18x"27dc4", 18x"27884", 18x"2734d", 18x"26e1d", 18x"268f6",
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18x"263d8", 18x"25ec1", 18x"259b3", 18x"254ac", 18x"24fad", 18x"24ab7", 18x"245c8", 18x"240e1",
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18x"23c01", 18x"23729", 18x"23259", 18x"22d90", 18x"228ce", 18x"22413", 18x"21f60", 18x"21ab4",
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18x"2160f", 18x"21172", 18x"20cdb", 18x"2084b", 18x"203c2", 18x"1ff40", 18x"1fac4", 18x"1f64f",
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18x"1f1e1", 18x"1ed79", 18x"1e918", 18x"1e4be", 18x"1e069", 18x"1dc1b", 18x"1d7d4", 18x"1d392",
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18x"1cf57", 18x"1cb22", 18x"1c6f3", 18x"1c2ca", 18x"1bea7", 18x"1ba8a", 18x"1b672", 18x"1b261",
|
|
18x"1ae55", 18x"1aa50", 18x"1a64f", 18x"1a255", 18x"19e60", 18x"19a70", 18x"19686", 18x"192a2",
|
|
18x"18ec3", 18x"18ae9", 18x"18715", 18x"18345", 18x"17f7c", 18x"17bb7", 18x"177f7", 18x"1743d",
|
|
18x"17087", 18x"16cd7", 18x"1692c", 18x"16585", 18x"161e4", 18x"15e47", 18x"15ab0", 18x"1571d",
|
|
18x"1538e", 18x"15005", 18x"14c80", 18x"14900", 18x"14584", 18x"1420d", 18x"13e9b", 18x"13b2d",
|
|
18x"137c3", 18x"1345e", 18x"130fe", 18x"12da2", 18x"12a4a", 18x"126f6", 18x"123a7", 18x"1205c",
|
|
18x"11d15", 18x"119d2", 18x"11694", 18x"11359", 18x"11023", 18x"10cf1", 18x"109c2", 18x"10698",
|
|
18x"10372", 18x"10050", 18x"0fd31", 18x"0fa17", 18x"0f700", 18x"0f3ed", 18x"0f0de", 18x"0edd3",
|
|
18x"0eacb", 18x"0e7c7", 18x"0e4c7", 18x"0e1ca", 18x"0ded2", 18x"0dbdc", 18x"0d8eb", 18x"0d5fc",
|
|
18x"0d312", 18x"0d02b", 18x"0cd47", 18x"0ca67", 18x"0c78a", 18x"0c4b1", 18x"0c1db", 18x"0bf09",
|
|
18x"0bc3a", 18x"0b96e", 18x"0b6a5", 18x"0b3e0", 18x"0b11e", 18x"0ae5f", 18x"0aba3", 18x"0a8eb",
|
|
18x"0a636", 18x"0a383", 18x"0a0d4", 18x"09e28", 18x"09b80", 18x"098da", 18x"09637", 18x"09397",
|
|
18x"090fb", 18x"08e61", 18x"08bca", 18x"08936", 18x"086a5", 18x"08417", 18x"0818c", 18x"07f04",
|
|
18x"07c7e", 18x"079fc", 18x"0777c", 18x"074ff", 18x"07284", 18x"0700d", 18x"06d98", 18x"06b26",
|
|
18x"068b6", 18x"0664a", 18x"063e0", 18x"06178", 18x"05f13", 18x"05cb1", 18x"05a52", 18x"057f5",
|
|
18x"0559a", 18x"05342", 18x"050ed", 18x"04e9a", 18x"04c4a", 18x"049fc", 18x"047b0", 18x"04567",
|
|
18x"04321", 18x"040dd", 18x"03e9b", 18x"03c5c", 18x"03a1f", 18x"037e4", 18x"035ac", 18x"03376",
|
|
18x"03142", 18x"02f11", 18x"02ce2", 18x"02ab5", 18x"0288b", 18x"02663", 18x"0243d", 18x"02219",
|
|
18x"01ff7", 18x"01dd8", 18x"01bbb", 18x"019a0", 18x"01787", 18x"01570", 18x"0135b", 18x"01149",
|
|
18x"00f39", 18x"00d2a", 18x"00b1e", 18x"00914", 18x"0070c", 18x"00506", 18x"00302", 18x"00100",
|
|
-- 1/sqrt(x) lookup table
|
|
-- Input is in the range [1, 4), i.e. two bits to the left of the
|
|
-- binary point. Those 2 bits index the following 3 blocks of 256 values.
|
|
-- 1.0 ... 1.9999
|
|
18x"3fe00", 18x"3fa06", 18x"3f612", 18x"3f224", 18x"3ee3a", 18x"3ea58", 18x"3e67c", 18x"3e2a4",
|
|
18x"3ded2", 18x"3db06", 18x"3d73e", 18x"3d37e", 18x"3cfc2", 18x"3cc0a", 18x"3c85a", 18x"3c4ae",
|
|
18x"3c106", 18x"3bd64", 18x"3b9c8", 18x"3b630", 18x"3b29e", 18x"3af10", 18x"3ab86", 18x"3a802",
|
|
18x"3a484", 18x"3a108", 18x"39d94", 18x"39a22", 18x"396b6", 18x"3934e", 18x"38fea", 18x"38c8c",
|
|
18x"38932", 18x"385dc", 18x"3828a", 18x"37f3e", 18x"37bf6", 18x"378b2", 18x"37572", 18x"37236",
|
|
18x"36efe", 18x"36bca", 18x"3689a", 18x"36570", 18x"36248", 18x"35f26", 18x"35c06", 18x"358ea",
|
|
18x"355d4", 18x"352c0", 18x"34fb0", 18x"34ca4", 18x"3499c", 18x"34698", 18x"34398", 18x"3409c",
|
|
18x"33da2", 18x"33aac", 18x"337bc", 18x"334cc", 18x"331e2", 18x"32efc", 18x"32c18", 18x"32938",
|
|
18x"3265a", 18x"32382", 18x"320ac", 18x"31dd8", 18x"31b0a", 18x"3183e", 18x"31576", 18x"312b0",
|
|
18x"30fee", 18x"30d2e", 18x"30a74", 18x"307ba", 18x"30506", 18x"30254", 18x"2ffa4", 18x"2fcf8",
|
|
18x"2fa4e", 18x"2f7a8", 18x"2f506", 18x"2f266", 18x"2efca", 18x"2ed2e", 18x"2ea98", 18x"2e804",
|
|
18x"2e572", 18x"2e2e4", 18x"2e058", 18x"2ddce", 18x"2db48", 18x"2d8c6", 18x"2d646", 18x"2d3c8",
|
|
18x"2d14c", 18x"2ced4", 18x"2cc5e", 18x"2c9ea", 18x"2c77a", 18x"2c50c", 18x"2c2a2", 18x"2c038",
|
|
18x"2bdd2", 18x"2bb70", 18x"2b90e", 18x"2b6b0", 18x"2b454", 18x"2b1fa", 18x"2afa4", 18x"2ad4e",
|
|
18x"2aafc", 18x"2a8ac", 18x"2a660", 18x"2a414", 18x"2a1cc", 18x"29f86", 18x"29d42", 18x"29b00",
|
|
18x"298c2", 18x"29684", 18x"2944a", 18x"29210", 18x"28fda", 18x"28da6", 18x"28b74", 18x"28946",
|
|
18x"28718", 18x"284ec", 18x"282c4", 18x"2809c", 18x"27e78", 18x"27c56", 18x"27a34", 18x"27816",
|
|
18x"275fa", 18x"273e0", 18x"271c8", 18x"26fb0", 18x"26d9c", 18x"26b8a", 18x"2697a", 18x"2676c",
|
|
18x"26560", 18x"26356", 18x"2614c", 18x"25f46", 18x"25d42", 18x"25b40", 18x"2593e", 18x"25740",
|
|
18x"25542", 18x"25348", 18x"2514e", 18x"24f58", 18x"24d62", 18x"24b6e", 18x"2497c", 18x"2478c",
|
|
18x"2459e", 18x"243b0", 18x"241c6", 18x"23fde", 18x"23df6", 18x"23c10", 18x"23a2c", 18x"2384a",
|
|
18x"2366a", 18x"2348c", 18x"232ae", 18x"230d2", 18x"22efa", 18x"22d20", 18x"22b4a", 18x"22976",
|
|
18x"227a2", 18x"225d2", 18x"22402", 18x"22234", 18x"22066", 18x"21e9c", 18x"21cd2", 18x"21b0a",
|
|
18x"21944", 18x"2177e", 18x"215ba", 18x"213fa", 18x"21238", 18x"2107a", 18x"20ebc", 18x"20d00",
|
|
18x"20b46", 18x"2098e", 18x"207d6", 18x"20620", 18x"2046c", 18x"202b8", 18x"20108", 18x"1ff58",
|
|
18x"1fda8", 18x"1fbfc", 18x"1fa50", 18x"1f8a4", 18x"1f6fc", 18x"1f554", 18x"1f3ae", 18x"1f208",
|
|
18x"1f064", 18x"1eec2", 18x"1ed22", 18x"1eb82", 18x"1e9e4", 18x"1e846", 18x"1e6aa", 18x"1e510",
|
|
18x"1e378", 18x"1e1e0", 18x"1e04a", 18x"1deb4", 18x"1dd20", 18x"1db8e", 18x"1d9fc", 18x"1d86c",
|
|
18x"1d6de", 18x"1d550", 18x"1d3c4", 18x"1d238", 18x"1d0ae", 18x"1cf26", 18x"1cd9e", 18x"1cc18",
|
|
18x"1ca94", 18x"1c910", 18x"1c78c", 18x"1c60a", 18x"1c48a", 18x"1c30c", 18x"1c18e", 18x"1c010",
|
|
18x"1be94", 18x"1bd1a", 18x"1bba0", 18x"1ba28", 18x"1b8b2", 18x"1b73c", 18x"1b5c6", 18x"1b452",
|
|
18x"1b2e0", 18x"1b16e", 18x"1affe", 18x"1ae8e", 18x"1ad20", 18x"1abb4", 18x"1aa46", 18x"1a8dc",
|
|
-- 2.0 ... 2.9999
|
|
18x"1a772", 18x"1a608", 18x"1a4a0", 18x"1a33a", 18x"1a1d4", 18x"1a070", 18x"19f0c", 18x"19da8",
|
|
18x"19c48", 18x"19ae6", 18x"19986", 18x"19828", 18x"196ca", 18x"1956e", 18x"19412", 18x"192b8",
|
|
18x"1915e", 18x"19004", 18x"18eae", 18x"18d56", 18x"18c00", 18x"18aac", 18x"18958", 18x"18804",
|
|
18x"186b2", 18x"18562", 18x"18412", 18x"182c2", 18x"18174", 18x"18026", 18x"17eda", 18x"17d8e",
|
|
18x"17c44", 18x"17afa", 18x"179b2", 18x"1786a", 18x"17724", 18x"175de", 18x"17498", 18x"17354",
|
|
18x"17210", 18x"170ce", 18x"16f8c", 18x"16e4c", 18x"16d0c", 18x"16bcc", 18x"16a8e", 18x"16950",
|
|
18x"16814", 18x"166d8", 18x"1659e", 18x"16464", 18x"1632a", 18x"161f2", 18x"160ba", 18x"15f84",
|
|
18x"15e4e", 18x"15d1a", 18x"15be6", 18x"15ab2", 18x"15980", 18x"1584e", 18x"1571c", 18x"155ec",
|
|
18x"154bc", 18x"1538e", 18x"15260", 18x"15134", 18x"15006", 18x"14edc", 18x"14db0", 18x"14c86",
|
|
18x"14b5e", 18x"14a36", 18x"1490e", 18x"147e6", 18x"146c0", 18x"1459a", 18x"14476", 18x"14352",
|
|
18x"14230", 18x"1410c", 18x"13fea", 18x"13eca", 18x"13daa", 18x"13c8a", 18x"13b6c", 18x"13a4e",
|
|
18x"13930", 18x"13814", 18x"136f8", 18x"135dc", 18x"134c2", 18x"133a8", 18x"1328e", 18x"13176",
|
|
18x"1305e", 18x"12f48", 18x"12e30", 18x"12d1a", 18x"12c06", 18x"12af2", 18x"129de", 18x"128ca",
|
|
18x"127b8", 18x"126a6", 18x"12596", 18x"12486", 18x"12376", 18x"12266", 18x"12158", 18x"1204a",
|
|
18x"11f3e", 18x"11e32", 18x"11d26", 18x"11c1a", 18x"11b10", 18x"11a06", 18x"118fc", 18x"117f4",
|
|
18x"116ec", 18x"115e4", 18x"114de", 18x"113d8", 18x"112d2", 18x"111ce", 18x"110ca", 18x"10fc6",
|
|
18x"10ec2", 18x"10dc0", 18x"10cbe", 18x"10bbc", 18x"10abc", 18x"109bc", 18x"108bc", 18x"107be",
|
|
18x"106c0", 18x"105c2", 18x"104c4", 18x"103c8", 18x"102cc", 18x"101d0", 18x"100d6", 18x"0ffdc",
|
|
18x"0fee2", 18x"0fdea", 18x"0fcf0", 18x"0fbf8", 18x"0fb02", 18x"0fa0a", 18x"0f914", 18x"0f81e",
|
|
18x"0f72a", 18x"0f636", 18x"0f542", 18x"0f44e", 18x"0f35a", 18x"0f268", 18x"0f176", 18x"0f086",
|
|
18x"0ef94", 18x"0eea4", 18x"0edb4", 18x"0ecc6", 18x"0ebd6", 18x"0eae8", 18x"0e9fa", 18x"0e90e",
|
|
18x"0e822", 18x"0e736", 18x"0e64a", 18x"0e55e", 18x"0e474", 18x"0e38a", 18x"0e2a0", 18x"0e1b8",
|
|
18x"0e0d0", 18x"0dfe8", 18x"0df00", 18x"0de1a", 18x"0dd32", 18x"0dc4c", 18x"0db68", 18x"0da82",
|
|
18x"0d99e", 18x"0d8ba", 18x"0d7d6", 18x"0d6f4", 18x"0d612", 18x"0d530", 18x"0d44e", 18x"0d36c",
|
|
18x"0d28c", 18x"0d1ac", 18x"0d0cc", 18x"0cfee", 18x"0cf0e", 18x"0ce30", 18x"0cd54", 18x"0cc76",
|
|
18x"0cb9a", 18x"0cabc", 18x"0c9e0", 18x"0c906", 18x"0c82a", 18x"0c750", 18x"0c676", 18x"0c59c",
|
|
18x"0c4c4", 18x"0c3ea", 18x"0c312", 18x"0c23a", 18x"0c164", 18x"0c08c", 18x"0bfb6", 18x"0bee0",
|
|
18x"0be0a", 18x"0bd36", 18x"0bc62", 18x"0bb8c", 18x"0baba", 18x"0b9e6", 18x"0b912", 18x"0b840",
|
|
18x"0b76e", 18x"0b69c", 18x"0b5cc", 18x"0b4fa", 18x"0b42a", 18x"0b35a", 18x"0b28a", 18x"0b1bc",
|
|
18x"0b0ee", 18x"0b01e", 18x"0af50", 18x"0ae84", 18x"0adb6", 18x"0acea", 18x"0ac1e", 18x"0ab52",
|
|
18x"0aa86", 18x"0a9bc", 18x"0a8f0", 18x"0a826", 18x"0a75c", 18x"0a694", 18x"0a5ca", 18x"0a502",
|
|
18x"0a43a", 18x"0a372", 18x"0a2aa", 18x"0a1e4", 18x"0a11c", 18x"0a056", 18x"09f90", 18x"09ecc",
|
|
-- 3.0 ... 3.9999
|
|
18x"09e06", 18x"09d42", 18x"09c7e", 18x"09bba", 18x"09af6", 18x"09a32", 18x"09970", 18x"098ae",
|
|
18x"097ec", 18x"0972a", 18x"09668", 18x"095a8", 18x"094e8", 18x"09426", 18x"09368", 18x"092a8",
|
|
18x"091e8", 18x"0912a", 18x"0906c", 18x"08fae", 18x"08ef0", 18x"08e32", 18x"08d76", 18x"08cba",
|
|
18x"08bfe", 18x"08b42", 18x"08a86", 18x"089ca", 18x"08910", 18x"08856", 18x"0879c", 18x"086e2",
|
|
18x"08628", 18x"08570", 18x"084b6", 18x"083fe", 18x"08346", 18x"0828e", 18x"081d8", 18x"08120",
|
|
18x"0806a", 18x"07fb4", 18x"07efe", 18x"07e48", 18x"07d92", 18x"07cde", 18x"07c2a", 18x"07b76",
|
|
18x"07ac2", 18x"07a0e", 18x"0795a", 18x"078a8", 18x"077f4", 18x"07742", 18x"07690", 18x"075de",
|
|
18x"0752e", 18x"0747c", 18x"073cc", 18x"0731c", 18x"0726c", 18x"071bc", 18x"0710c", 18x"0705e",
|
|
18x"06fae", 18x"06f00", 18x"06e52", 18x"06da4", 18x"06cf6", 18x"06c4a", 18x"06b9c", 18x"06af0",
|
|
18x"06a44", 18x"06998", 18x"068ec", 18x"06840", 18x"06796", 18x"066ea", 18x"06640", 18x"06596",
|
|
18x"064ec", 18x"06442", 18x"0639a", 18x"062f0", 18x"06248", 18x"061a0", 18x"060f8", 18x"06050",
|
|
18x"05fa8", 18x"05f00", 18x"05e5a", 18x"05db4", 18x"05d0e", 18x"05c68", 18x"05bc2", 18x"05b1c",
|
|
18x"05a76", 18x"059d2", 18x"0592e", 18x"05888", 18x"057e4", 18x"05742", 18x"0569e", 18x"055fa",
|
|
18x"05558", 18x"054b6", 18x"05412", 18x"05370", 18x"052ce", 18x"0522e", 18x"0518c", 18x"050ec",
|
|
18x"0504a", 18x"04faa", 18x"04f0a", 18x"04e6a", 18x"04dca", 18x"04d2c", 18x"04c8c", 18x"04bee",
|
|
18x"04b50", 18x"04ab0", 18x"04a12", 18x"04976", 18x"048d8", 18x"0483a", 18x"0479e", 18x"04700",
|
|
18x"04664", 18x"045c8", 18x"0452c", 18x"04490", 18x"043f6", 18x"0435a", 18x"042c0", 18x"04226",
|
|
18x"0418a", 18x"040f0", 18x"04056", 18x"03fbe", 18x"03f24", 18x"03e8c", 18x"03df2", 18x"03d5a",
|
|
18x"03cc2", 18x"03c2a", 18x"03b92", 18x"03afa", 18x"03a62", 18x"039cc", 18x"03934", 18x"0389e",
|
|
18x"03808", 18x"03772", 18x"036dc", 18x"03646", 18x"035b2", 18x"0351c", 18x"03488", 18x"033f2",
|
|
18x"0335e", 18x"032ca", 18x"03236", 18x"031a2", 18x"03110", 18x"0307c", 18x"02fea", 18x"02f56",
|
|
18x"02ec4", 18x"02e32", 18x"02da0", 18x"02d0e", 18x"02c7c", 18x"02bec", 18x"02b5a", 18x"02aca",
|
|
18x"02a38", 18x"029a8", 18x"02918", 18x"02888", 18x"027f8", 18x"0276a", 18x"026da", 18x"0264a",
|
|
18x"025bc", 18x"0252e", 18x"024a0", 18x"02410", 18x"02384", 18x"022f6", 18x"02268", 18x"021da",
|
|
18x"0214e", 18x"020c0", 18x"02034", 18x"01fa8", 18x"01f1c", 18x"01e90", 18x"01e04", 18x"01d78",
|
|
18x"01cee", 18x"01c62", 18x"01bd8", 18x"01b4c", 18x"01ac2", 18x"01a38", 18x"019ae", 18x"01924",
|
|
18x"0189c", 18x"01812", 18x"01788", 18x"01700", 18x"01676", 18x"015ee", 18x"01566", 18x"014de",
|
|
18x"01456", 18x"013ce", 18x"01346", 18x"012c0", 18x"01238", 18x"011b2", 18x"0112c", 18x"010a4",
|
|
18x"0101e", 18x"00f98", 18x"00f12", 18x"00e8c", 18x"00e08", 18x"00d82", 18x"00cfe", 18x"00c78",
|
|
18x"00bf4", 18x"00b70", 18x"00aec", 18x"00a68", 18x"009e4", 18x"00960", 18x"008dc", 18x"00858",
|
|
18x"007d6", 18x"00752", 18x"006d0", 18x"0064e", 18x"005cc", 18x"0054a", 18x"004c8", 18x"00446",
|
|
18x"003c4", 18x"00342", 18x"002c2", 18x"00240", 18x"001c0", 18x"00140", 18x"000c0", 18x"00040"
|
|
);
|
|
|
|
-- Left and right shifter with 120 bit input and 64 bit output.
|
|
-- Shifts inp left by shift bits and returns the upper 64 bits of
|
|
-- the result. The shift parameter is interpreted as a signed
|
|
-- number in the range -64..63, with negative values indicating
|
|
-- right shifts.
|
|
function shifter_64(inp: std_ulogic_vector(119 downto 0);
|
|
shift: std_ulogic_vector(6 downto 0))
|
|
return std_ulogic_vector is
|
|
variable s1 : std_ulogic_vector(94 downto 0);
|
|
variable s2 : std_ulogic_vector(70 downto 0);
|
|
variable shift_result : std_ulogic_vector(63 downto 0);
|
|
begin
|
|
case shift(6 downto 5) is
|
|
when "00" =>
|
|
s1 := inp(119 downto 25);
|
|
when "01" =>
|
|
s1 := inp(87 downto 0) & "0000000";
|
|
when "10" =>
|
|
s1 := x"0000000000000000" & inp(119 downto 89);
|
|
when others =>
|
|
s1 := x"00000000" & inp(119 downto 57);
|
|
end case;
|
|
case shift(4 downto 3) is
|
|
when "00" =>
|
|
s2 := s1(94 downto 24);
|
|
when "01" =>
|
|
s2 := s1(86 downto 16);
|
|
when "10" =>
|
|
s2 := s1(78 downto 8);
|
|
when others =>
|
|
s2 := s1(70 downto 0);
|
|
end case;
|
|
case shift(2 downto 0) is
|
|
when "000" =>
|
|
shift_result := s2(70 downto 7);
|
|
when "001" =>
|
|
shift_result := s2(69 downto 6);
|
|
when "010" =>
|
|
shift_result := s2(68 downto 5);
|
|
when "011" =>
|
|
shift_result := s2(67 downto 4);
|
|
when "100" =>
|
|
shift_result := s2(66 downto 3);
|
|
when "101" =>
|
|
shift_result := s2(65 downto 2);
|
|
when "110" =>
|
|
shift_result := s2(64 downto 1);
|
|
when others =>
|
|
shift_result := s2(63 downto 0);
|
|
end case;
|
|
return shift_result;
|
|
end;
|
|
|
|
-- Generate a mask with 0-bits on the left and 1-bits on the right which
|
|
-- selects the bits will be lost in doing a right shift. The shift
|
|
-- parameter is the bottom 6 bits of a negative shift count,
|
|
-- indicating a right shift.
|
|
function right_mask(shift: unsigned(5 downto 0)) return std_ulogic_vector is
|
|
variable mask_result: std_ulogic_vector(63 downto 0);
|
|
begin
|
|
mask_result := (others => '0');
|
|
if is_X(shift) then
|
|
mask_result := (others => 'X');
|
|
return mask_result;
|
|
end if;
|
|
for i in 0 to 63 loop
|
|
if i >= shift then
|
|
mask_result(63 - i) := '1';
|
|
end if;
|
|
end loop;
|
|
return mask_result;
|
|
end;
|
|
|
|
-- Split a DP floating-point number into components and work out its class.
|
|
-- If is_int = 1, the input is considered an integer
|
|
function decode_dp(fpr: std_ulogic_vector(63 downto 0); is_fp: std_ulogic;
|
|
is_32bint: std_ulogic; is_signed: std_ulogic) return fpu_reg_type is
|
|
variable reg : fpu_reg_type;
|
|
variable exp_nz : std_ulogic;
|
|
variable exp_ao : std_ulogic;
|
|
variable frac_nz : std_ulogic;
|
|
variable low_nz : std_ulogic;
|
|
variable cls : std_ulogic_vector(2 downto 0);
|
|
begin
|
|
reg.negative := fpr(63);
|
|
reg.denorm := '0';
|
|
exp_nz := or (fpr(62 downto 52));
|
|
exp_ao := and (fpr(62 downto 52));
|
|
frac_nz := or (fpr(51 downto 0));
|
|
low_nz := or (fpr(31 downto 0));
|
|
if is_fp = '1' then
|
|
reg.denorm := frac_nz and not exp_nz;
|
|
reg.exponent := signed(resize(unsigned(fpr(62 downto 52)), EXP_BITS)) - to_signed(1023, EXP_BITS);
|
|
if exp_nz = '0' then
|
|
reg.exponent := to_signed(-1022, EXP_BITS);
|
|
end if;
|
|
reg.mantissa := std_ulogic_vector(shift_left(resize(unsigned(exp_nz & fpr(51 downto 0)), 64),
|
|
UNIT_BIT - 52));
|
|
cls := exp_ao & exp_nz & frac_nz;
|
|
case cls is
|
|
when "000" => reg.class := ZERO;
|
|
when "001" => reg.class := FINITE; -- denormalized
|
|
when "010" => reg.class := FINITE;
|
|
when "011" => reg.class := FINITE;
|
|
when "110" => reg.class := INFINITY;
|
|
when others => reg.class := NAN;
|
|
end case;
|
|
elsif is_32bint = '1' then
|
|
reg.negative := fpr(31);
|
|
reg.mantissa(31 downto 0) := fpr(31 downto 0);
|
|
reg.mantissa(63 downto 32) := (others => (is_signed and fpr(31)));
|
|
reg.exponent := (others => '0');
|
|
if low_nz = '1' then
|
|
reg.class := FINITE;
|
|
else
|
|
reg.class := ZERO;
|
|
end if;
|
|
else
|
|
reg.mantissa := fpr;
|
|
reg.exponent := (others => '0');
|
|
if (fpr(63) or exp_nz or frac_nz) = '1' then
|
|
reg.class := FINITE;
|
|
else
|
|
reg.class := ZERO;
|
|
end if;
|
|
end if;
|
|
return reg;
|
|
end;
|
|
|
|
-- Construct a DP floating-point result from components
|
|
function pack_dp(negative: std_ulogic; class: fp_number_class; exp: signed(EXP_BITS-1 downto 0);
|
|
mantissa: std_ulogic_vector; single_prec: std_ulogic; quieten_nan: std_ulogic;
|
|
negate: std_ulogic; is_subtract: std_ulogic; round_mode: std_ulogic_vector)
|
|
return std_ulogic_vector is
|
|
variable dp_result : std_ulogic_vector(63 downto 0);
|
|
variable sign : std_ulogic;
|
|
begin
|
|
dp_result := (others => '0');
|
|
sign := negative;
|
|
case class is
|
|
when ZERO =>
|
|
if is_subtract = '1' then
|
|
-- set result sign depending on rounding mode
|
|
sign := round_mode(0) and round_mode(1);
|
|
end if;
|
|
when FINITE =>
|
|
if mantissa(UNIT_BIT) = '1' then
|
|
-- normalized number
|
|
dp_result(62 downto 52) := std_ulogic_vector(resize(exp, 11) + 1023);
|
|
end if;
|
|
dp_result(51 downto 29) := mantissa(UNIT_BIT - 1 downto SP_LSB);
|
|
if single_prec = '0' then
|
|
dp_result(28 downto 0) := mantissa(SP_LSB - 1 downto DP_LSB);
|
|
end if;
|
|
when INFINITY =>
|
|
dp_result(62 downto 52) := "11111111111";
|
|
when NAN =>
|
|
dp_result(62 downto 52) := "11111111111";
|
|
dp_result(51) := quieten_nan or mantissa(QNAN_BIT);
|
|
dp_result(50 downto 29) := mantissa(QNAN_BIT - 1 downto SP_LSB);
|
|
if single_prec = '0' then
|
|
dp_result(28 downto 0) := mantissa(SP_LSB - 1 downto DP_LSB);
|
|
end if;
|
|
end case;
|
|
dp_result(63) := sign xor negate;
|
|
return dp_result;
|
|
end;
|
|
|
|
-- Determine whether to increment when rounding
|
|
-- Returns rounding_inc & inexact
|
|
-- If single_prec = 1, assumes x includes the bottom 31 (== SP_LSB - 2)
|
|
-- bits of the mantissa already (usually arranged by setting set_x = 1 earlier).
|
|
function fp_rounding(mantissa: std_ulogic_vector(63 downto 0); x: std_ulogic;
|
|
single_prec: std_ulogic; rn: std_ulogic_vector(2 downto 0);
|
|
sign: std_ulogic)
|
|
return std_ulogic_vector is
|
|
variable grx : std_ulogic_vector(2 downto 0);
|
|
variable ret : std_ulogic_vector(1 downto 0);
|
|
variable lsb : std_ulogic;
|
|
begin
|
|
if single_prec = '0' then
|
|
grx := mantissa(DP_GBIT downto DP_RBIT) & (x or (or mantissa(DP_RBIT - 1 downto 0)));
|
|
lsb := mantissa(DP_LSB);
|
|
else
|
|
grx := mantissa(SP_GBIT downto SP_RBIT) & x;
|
|
lsb := mantissa(SP_LSB);
|
|
end if;
|
|
ret(1) := '0';
|
|
ret(0) := or (grx);
|
|
case rn(1 downto 0) is
|
|
when "00" => -- round to nearest
|
|
if grx = "100" and rn(2) = '0' then
|
|
ret(1) := lsb; -- tie, round to even
|
|
else
|
|
ret(1) := grx(2);
|
|
end if;
|
|
when "01" => -- round towards zero
|
|
when others => -- round towards +/- inf
|
|
if rn(0) = sign then
|
|
-- round towards greater magnitude
|
|
ret(1) := ret(0);
|
|
end if;
|
|
end case;
|
|
return ret;
|
|
end;
|
|
|
|
-- Determine result flags to write into the FPSCR
|
|
function result_flags(sign: std_ulogic; class: fp_number_class; unitbit: std_ulogic)
|
|
return std_ulogic_vector is
|
|
begin
|
|
case class is
|
|
when ZERO =>
|
|
return sign & "0010";
|
|
when FINITE =>
|
|
return (not unitbit) & sign & (not sign) & "00";
|
|
when INFINITY =>
|
|
return '0' & sign & (not sign) & "01";
|
|
when NAN =>
|
|
return "10001";
|
|
end case;
|
|
end;
|
|
|
|
begin
|
|
fpu_multiply_0: entity work.multiply
|
|
port map (
|
|
clk => clk,
|
|
m_in => f_to_multiply,
|
|
m_out => multiply_to_f
|
|
);
|
|
|
|
fpu_0: process(clk)
|
|
begin
|
|
if rising_edge(clk) then
|
|
if rst = '1' or flush_in = '1' then
|
|
r.state <= IDLE;
|
|
r.busy <= '0';
|
|
r.f2stall <= '0';
|
|
r.instr_done <= '0';
|
|
r.complete <= '0';
|
|
r.illegal <= '0';
|
|
r.do_intr <= '0';
|
|
r.writing_fpr <= '0';
|
|
r.writing_cr <= '0';
|
|
r.writing_xer <= '0';
|
|
r.fpscr <= (others => '0');
|
|
r.write_reg <= (others =>'0');
|
|
r.complete_tag.valid <= '0';
|
|
r.cr_mask <= (others =>'0');
|
|
r.cr_result <= (others =>'0');
|
|
r.instr_tag.valid <= '0';
|
|
if rst = '1' then
|
|
r.fpscr <= (others => '0');
|
|
r.comm_fpscr <= (others => '0');
|
|
elsif r.do_intr = '0' then
|
|
-- flush_in = 1 and not due to us generating an interrupt,
|
|
-- roll back to committed fpscr
|
|
r.fpscr <= r.comm_fpscr;
|
|
end if;
|
|
else
|
|
assert not (r.state /= IDLE and e_in.valid = '1') severity failure;
|
|
r <= rin;
|
|
end if;
|
|
end if;
|
|
end process;
|
|
|
|
-- synchronous reads from lookup table
|
|
lut_access: process(clk)
|
|
variable addrhi : std_ulogic_vector(1 downto 0);
|
|
variable addr : std_ulogic_vector(9 downto 0);
|
|
begin
|
|
if rising_edge(clk) then
|
|
if r.is_sqrt = '1' then
|
|
addrhi := r.b.mantissa(UNIT_BIT + 1 downto UNIT_BIT);
|
|
else
|
|
addrhi := "00";
|
|
end if;
|
|
addr := addrhi & r.b.mantissa(UNIT_BIT - 1 downto UNIT_BIT - 8);
|
|
if is_X(addr) then
|
|
inverse_est <= (others => 'X');
|
|
else
|
|
inverse_est <= '1' & inverse_table(to_integer(unsigned(addr)));
|
|
end if;
|
|
end if;
|
|
end process;
|
|
|
|
e_out.busy <= r.busy;
|
|
e_out.f2stall <= r.f2stall;
|
|
e_out.exception <= r.fpscr(FPSCR_FEX);
|
|
|
|
-- Note that the cycle where r.complete = 1 for an instruction can be as
|
|
-- late as the second cycle of the following instruction (i.e. in the state
|
|
-- following IDLE state). Hence it is important that none of the fields of
|
|
-- r that are used below are modified in IDLE state.
|
|
w_out.valid <= r.complete;
|
|
w_out.instr_tag <= r.complete_tag;
|
|
w_out.write_enable <= r.writing_fpr and r.complete;
|
|
w_out.write_reg <= r.write_reg;
|
|
w_out.write_data <= fp_result;
|
|
w_out.write_cr_enable <= r.writing_cr and r.complete;
|
|
w_out.write_cr_mask <= r.cr_mask;
|
|
w_out.write_cr_data <= r.cr_result & r.cr_result & r.cr_result & r.cr_result &
|
|
r.cr_result & r.cr_result & r.cr_result & r.cr_result;
|
|
w_out.write_xerc <= r.writing_xer and r.complete;
|
|
w_out.xerc <= r.xerc_result;
|
|
w_out.interrupt <= r.do_intr;
|
|
w_out.intr_vec <= 16#700#;
|
|
w_out.srr1 <= (47-44 => r.illegal, 47-43 => not r.illegal, others => '0');
|
|
|
|
fpu_1: process(all)
|
|
variable v : reg_type;
|
|
variable adec : fpu_reg_type;
|
|
variable bdec : fpu_reg_type;
|
|
variable cdec : fpu_reg_type;
|
|
variable fpscr_mask : std_ulogic_vector(31 downto 0);
|
|
variable j, k : integer;
|
|
variable flm : std_ulogic_vector(7 downto 0);
|
|
variable fpin_a : std_ulogic;
|
|
variable fpin_b : std_ulogic;
|
|
variable fpin_c : std_ulogic;
|
|
variable is_32bint : std_ulogic;
|
|
variable mask : std_ulogic_vector(63 downto 0);
|
|
variable in_a0 : std_ulogic_vector(63 downto 0);
|
|
variable in_b0 : std_ulogic_vector(63 downto 0);
|
|
variable misc : std_ulogic_vector(63 downto 0);
|
|
variable shift_res : std_ulogic_vector(63 downto 0);
|
|
variable round : std_ulogic_vector(1 downto 0);
|
|
variable update_fx : std_ulogic;
|
|
variable arith_done : std_ulogic;
|
|
variable invalid : std_ulogic;
|
|
variable zero_divide : std_ulogic;
|
|
variable mant_nz : std_ulogic;
|
|
variable min_exp : signed(EXP_BITS-1 downto 0);
|
|
variable max_exp : signed(EXP_BITS-1 downto 0);
|
|
variable bias_exp : signed(EXP_BITS-1 downto 0);
|
|
variable new_exp : signed(EXP_BITS-1 downto 0);
|
|
variable exp_tiny : std_ulogic;
|
|
variable exp_huge : std_ulogic;
|
|
variable clz : std_ulogic_vector(5 downto 0);
|
|
variable set_x : std_ulogic;
|
|
variable mshift : signed(EXP_BITS-1 downto 0);
|
|
variable need_check : std_ulogic;
|
|
variable msb : std_ulogic;
|
|
variable is_add : std_ulogic;
|
|
variable set_a : std_ulogic;
|
|
variable set_a_exp : std_ulogic;
|
|
variable set_a_mant : std_ulogic;
|
|
variable set_a_hi : std_ulogic;
|
|
variable set_a_lo : std_ulogic;
|
|
variable set_b : std_ulogic;
|
|
variable set_b_mant : std_ulogic;
|
|
variable set_c : std_ulogic;
|
|
variable set_y : std_ulogic;
|
|
variable set_s : std_ulogic;
|
|
variable qnan_result : std_ulogic;
|
|
variable px_nz : std_ulogic;
|
|
variable pcmpb_eq : std_ulogic;
|
|
variable pcmpb_lt : std_ulogic;
|
|
variable pcmpc_eq : std_ulogic;
|
|
variable pcmpc_lt : std_ulogic;
|
|
variable pshift : std_ulogic;
|
|
variable renorm_sqrt : std_ulogic;
|
|
variable sqrt_exp : signed(EXP_BITS-1 downto 0);
|
|
variable shiftin : std_ulogic;
|
|
variable shiftin0 : std_ulogic;
|
|
variable mulexp : signed(EXP_BITS-1 downto 0);
|
|
variable maddend : std_ulogic_vector(127 downto 0);
|
|
variable sum : std_ulogic_vector(63 downto 0);
|
|
variable round_inc : std_ulogic_vector(63 downto 0);
|
|
variable rbit_inc : std_ulogic;
|
|
variable mult_mask : std_ulogic;
|
|
variable sign_bit : std_ulogic;
|
|
variable rnd_b32 : std_ulogic;
|
|
variable rexp_in1 : signed(EXP_BITS-1 downto 0);
|
|
variable rexp_in2 : signed(EXP_BITS-1 downto 0);
|
|
variable rexp_cin : std_ulogic;
|
|
variable rexp_sum : signed(EXP_BITS-1 downto 0);
|
|
variable rsh_in1 : signed(EXP_BITS-1 downto 0);
|
|
variable rsh_in2 : signed(EXP_BITS-1 downto 0);
|
|
variable exec_state : state_t;
|
|
variable opcbits : std_ulogic_vector(4 downto 0);
|
|
variable int_result : std_ulogic;
|
|
variable illegal : std_ulogic;
|
|
begin
|
|
v := r;
|
|
v.complete := '0';
|
|
v.do_intr := '0';
|
|
is_32bint := '0';
|
|
exec_state := IDLE;
|
|
|
|
if r.complete = '1' or r.do_intr = '1' then
|
|
v.instr_done := '0';
|
|
v.writing_fpr := '0';
|
|
v.writing_cr := '0';
|
|
v.writing_xer := '0';
|
|
v.comm_fpscr := r.fpscr;
|
|
v.illegal := '0';
|
|
end if;
|
|
|
|
-- capture incoming instruction
|
|
if e_in.valid = '1' then
|
|
v.insn := e_in.insn;
|
|
v.op := e_in.op;
|
|
v.instr_tag := e_in.itag;
|
|
v.fe_mode := or (e_in.fe_mode);
|
|
v.dest_fpr := e_in.frt;
|
|
v.single_prec := e_in.single;
|
|
v.is_signed := e_in.is_signed;
|
|
v.rc := e_in.rc;
|
|
v.fp_rc := '0';
|
|
v.is_cmp := e_in.out_cr;
|
|
v.oe := e_in.oe;
|
|
v.m32b := e_in.m32b;
|
|
v.xerc := e_in.xerc;
|
|
v.longmask := '0';
|
|
v.integer_op := '0';
|
|
v.divext := '0';
|
|
v.divmod := '0';
|
|
v.is_sqrt := '0';
|
|
v.is_multiply := '0';
|
|
fpin_a := '0';
|
|
fpin_b := '0';
|
|
fpin_c := '0';
|
|
v.use_a := e_in.valid_a;
|
|
v.use_b := e_in.valid_b;
|
|
v.use_c := e_in.valid_c;
|
|
v.round_mode := '0' & r.fpscr(FPSCR_RN+1 downto FPSCR_RN);
|
|
case e_in.op is
|
|
when OP_FP_ARITH =>
|
|
fpin_a := e_in.valid_a;
|
|
fpin_b := e_in.valid_b;
|
|
fpin_c := e_in.valid_c;
|
|
v.longmask := e_in.single;
|
|
v.fp_rc := e_in.rc;
|
|
exec_state := arith_decode(to_integer(unsigned(e_in.insn(5 downto 1))));
|
|
if e_in.insn(5 downto 1) = "11001" or e_in.insn(5 downto 3) = "111" then
|
|
v.is_multiply := '1';
|
|
end if;
|
|
if e_in.insn(5 downto 1) = "10110" or e_in.insn(5 downto 1) = "11010" then
|
|
v.is_sqrt := '1';
|
|
end if;
|
|
if e_in.insn(5 downto 1) = "01111" then
|
|
v.round_mode := "001";
|
|
end if;
|
|
when OP_FP_CMP =>
|
|
fpin_a := e_in.valid_a;
|
|
fpin_b := e_in.valid_b;
|
|
exec_state := cmp_decode(to_integer(unsigned(e_in.insn(8 downto 6))));
|
|
when OP_FP_MISC =>
|
|
v.fp_rc := e_in.rc;
|
|
opcbits := e_in.insn(10) & e_in.insn(8) & e_in.insn(4) & e_in.insn(2) & e_in.insn(1);
|
|
exec_state := misc_decode(to_integer(unsigned(opcbits)));
|
|
when OP_FP_MOVE =>
|
|
v.fp_rc := e_in.rc;
|
|
fpin_a := e_in.valid_a;
|
|
fpin_b := e_in.valid_b;
|
|
fpin_c := e_in.valid_c;
|
|
if e_in.insn(5) = '0' then
|
|
exec_state := DO_FMR;
|
|
else
|
|
exec_state := DO_FSEL;
|
|
end if;
|
|
when OP_DIV =>
|
|
v.integer_op := '1';
|
|
is_32bint := e_in.single;
|
|
exec_state := DO_IDIVMOD;
|
|
when OP_DIVE =>
|
|
v.integer_op := '1';
|
|
v.divext := '1';
|
|
is_32bint := e_in.single;
|
|
exec_state := DO_IDIVMOD;
|
|
when OP_MOD =>
|
|
v.integer_op := '1';
|
|
v.divmod := '1';
|
|
is_32bint := e_in.single;
|
|
exec_state := DO_IDIVMOD;
|
|
when others =>
|
|
exec_state := DO_ILLEGAL;
|
|
end case;
|
|
v.quieten_nan := '1';
|
|
v.tiny := '0';
|
|
v.denorm := '0';
|
|
v.is_subtract := '0';
|
|
v.add_bsmall := '0';
|
|
v.doing_ftdiv := "00";
|
|
v.int_ovf := '0';
|
|
v.div_close := '0';
|
|
|
|
adec := decode_dp(e_in.fra, fpin_a, is_32bint, e_in.is_signed);
|
|
bdec := decode_dp(e_in.frb, fpin_b, is_32bint, e_in.is_signed);
|
|
cdec := decode_dp(e_in.frc, fpin_c, '0', '0');
|
|
v.a := adec;
|
|
v.b := bdec;
|
|
v.c := cdec;
|
|
|
|
v.exp_cmp := '0';
|
|
if adec.exponent > bdec.exponent then
|
|
v.exp_cmp := '1';
|
|
end if;
|
|
v.madd_cmp := '0';
|
|
if (adec.exponent + cdec.exponent + 1) >= bdec.exponent then
|
|
v.madd_cmp := '1';
|
|
end if;
|
|
|
|
v.a_hi := 8x"0";
|
|
v.a_lo := 56x"0";
|
|
end if;
|
|
|
|
r_hi_nz <= or (r.r(UNIT_BIT + 1 downto SP_LSB));
|
|
r_lo_nz <= or (r.r(SP_LSB - 1 downto DP_LSB));
|
|
r_gt_1 <= or (r.r(63 downto 1));
|
|
s_nz <= or (r.s);
|
|
|
|
if r.single_prec = '0' then
|
|
if r.doing_ftdiv(1) = '0' then
|
|
max_exp := to_signed(1023, EXP_BITS);
|
|
else
|
|
max_exp := to_signed(1020, EXP_BITS);
|
|
end if;
|
|
if r.doing_ftdiv(0) = '0' then
|
|
min_exp := to_signed(-1022, EXP_BITS);
|
|
else
|
|
min_exp := to_signed(-1021, EXP_BITS);
|
|
end if;
|
|
bias_exp := to_signed(1536, EXP_BITS);
|
|
else
|
|
max_exp := to_signed(127, EXP_BITS);
|
|
min_exp := to_signed(-126, EXP_BITS);
|
|
bias_exp := to_signed(192, EXP_BITS);
|
|
end if;
|
|
new_exp := r.result_exp - r.shift;
|
|
exp_tiny := '0';
|
|
exp_huge := '0';
|
|
if is_X(new_exp) or is_X(min_exp) then
|
|
exp_tiny := 'X';
|
|
elsif new_exp < min_exp then
|
|
exp_tiny := '1';
|
|
end if;
|
|
if is_X(new_exp) or is_X(min_exp) then
|
|
exp_huge := 'X';
|
|
elsif new_exp > max_exp then
|
|
exp_huge := '1';
|
|
end if;
|
|
|
|
-- Compare P with zero and with B
|
|
px_nz := or (r.p(UNIT_BIT + 1 downto 4));
|
|
pcmpb_eq := '0';
|
|
if r.p(59 downto 4) = r.b.mantissa(UNIT_BIT + 1 downto DP_RBIT) then
|
|
pcmpb_eq := '1';
|
|
end if;
|
|
pcmpb_lt := '0';
|
|
if is_X(r.p(59 downto 4)) or is_X(r.b.mantissa(55 downto 0)) then
|
|
pcmpb_lt := 'X';
|
|
elsif unsigned(r.p(59 downto 4)) < unsigned(r.b.mantissa(UNIT_BIT + 1 downto DP_RBIT)) then
|
|
pcmpb_lt := '1';
|
|
end if;
|
|
pcmpc_eq := '0';
|
|
if r.p = r.c.mantissa then
|
|
pcmpc_eq := '1';
|
|
end if;
|
|
pcmpc_lt := '0';
|
|
if is_X(r.p) or is_X(r.c.mantissa) then
|
|
pcmpc_lt := 'X';
|
|
elsif unsigned(r.p) < unsigned(r.c.mantissa) then
|
|
pcmpc_lt := '1';
|
|
end if;
|
|
|
|
v.update_fprf := '0';
|
|
v.first := '0';
|
|
v.opsel_a := AIN_R;
|
|
opsel_ainv <= '0';
|
|
opsel_mask <= '0';
|
|
opsel_b <= BIN_ZERO;
|
|
opsel_binv <= '0';
|
|
opsel_r <= RES_SUM;
|
|
opsel_s <= S_ZERO;
|
|
carry_in <= '0';
|
|
misc_sel <= "0000";
|
|
fpscr_mask := (others => '1');
|
|
update_fx := '0';
|
|
arith_done := '0';
|
|
invalid := '0';
|
|
zero_divide := '0';
|
|
set_x := '0';
|
|
qnan_result := '0';
|
|
set_a := '0';
|
|
set_a_exp := '0';
|
|
set_a_mant := '0';
|
|
set_a_hi := '0';
|
|
set_a_lo := '0';
|
|
set_b := '0';
|
|
set_b_mant := '0';
|
|
set_c := '0';
|
|
set_s := '0';
|
|
f_to_multiply.is_signed <= '0';
|
|
f_to_multiply.valid <= '0';
|
|
msel_1 <= MUL1_A;
|
|
msel_2 <= MUL2_C;
|
|
msel_add <= MULADD_ZERO;
|
|
msel_inv <= '0';
|
|
set_y := '0';
|
|
pshift := '0';
|
|
renorm_sqrt := '0';
|
|
shiftin := '0';
|
|
shiftin0 := '0';
|
|
rbit_inc := '0';
|
|
mult_mask := '0';
|
|
rnd_b32 := '0';
|
|
int_result := '0';
|
|
illegal := '0';
|
|
|
|
re_sel1 <= REXP1_ZERO;
|
|
re_sel2 <= REXP2_CON;
|
|
re_con2 <= RECON2_ZERO;
|
|
re_neg1 <= '0';
|
|
re_neg2 <= '0';
|
|
re_set_result <= '0';
|
|
rs_sel1 <= RSH1_ZERO;
|
|
rs_sel2 <= RSH2_CON;
|
|
rs_con2 <= RSCON2_ZERO;
|
|
rs_neg1 <= '0';
|
|
rs_neg2 <= '0';
|
|
rs_norm <= '0';
|
|
|
|
case r.state is
|
|
when IDLE =>
|
|
v.invalid := '0';
|
|
v.negate := '0';
|
|
if e_in.valid = '1' then
|
|
v.opsel_a := AIN_B;
|
|
v.busy := '1';
|
|
if e_in.op = OP_FP_ARITH and e_in.valid_a = '1' and
|
|
(e_in.valid_b = '0' or e_in.valid_c = '0') then
|
|
v.opsel_a := AIN_A;
|
|
end if;
|
|
if e_in.op = OP_FP_ARITH then
|
|
-- input selection for denorm cases
|
|
case e_in.insn(5 downto 1) is
|
|
when "10010" => -- fdiv
|
|
if v.b.mantissa(UNIT_BIT) = '0' and v.a.mantissa(UNIT_BIT) = '1' then
|
|
v.opsel_a := AIN_B;
|
|
end if;
|
|
when "11001" => -- fmul
|
|
if v.c.mantissa(UNIT_BIT) = '0' and v.a.mantissa(UNIT_BIT) = '1' then
|
|
v.opsel_a := AIN_C;
|
|
end if;
|
|
when "11100" | "11101" | "11110" | "11111" => -- fmadd etc.
|
|
if v.a.mantissa(UNIT_BIT) = '0' then
|
|
v.opsel_a := AIN_A;
|
|
elsif v.c.mantissa(UNIT_BIT) = '0' then
|
|
v.opsel_a := AIN_C;
|
|
end if;
|
|
when others =>
|
|
end case;
|
|
end if;
|
|
v.state := exec_state;
|
|
end if;
|
|
v.x := '0';
|
|
v.old_exc := r.fpscr(FPSCR_VX downto FPSCR_XX);
|
|
set_s := '1';
|
|
|
|
when DO_ILLEGAL =>
|
|
illegal := '1';
|
|
v.instr_done := '1';
|
|
|
|
when DO_MCRFS =>
|
|
j := to_integer(unsigned(insn_bfa(r.insn)));
|
|
for i in 0 to 7 loop
|
|
if i = j then
|
|
k := (7 - i) * 4;
|
|
v.cr_result := r.fpscr(k + 3 downto k);
|
|
fpscr_mask(k + 3 downto k) := "0000";
|
|
end if;
|
|
end loop;
|
|
v.fpscr := r.fpscr and (fpscr_mask or x"6007F8FF");
|
|
v.instr_done := '1';
|
|
|
|
when DO_FTDIV =>
|
|
v.instr_done := '1';
|
|
v.cr_result := "0000";
|
|
if r.a.class = INFINITY or r.b.class = ZERO or r.b.class = INFINITY or
|
|
(r.b.class = FINITE and r.b.mantissa(UNIT_BIT) = '0') then
|
|
v.cr_result(2) := '1';
|
|
end if;
|
|
if r.a.class = NAN or r.a.class = INFINITY or
|
|
r.b.class = NAN or r.b.class = ZERO or r.b.class = INFINITY or
|
|
(r.a.class = FINITE and r.a.exponent <= to_signed(-970, EXP_BITS)) then
|
|
v.cr_result(1) := '1';
|
|
else
|
|
v.doing_ftdiv := "11";
|
|
v.first := '1';
|
|
v.state := FTDIV_1;
|
|
v.instr_done := '0';
|
|
end if;
|
|
|
|
when DO_FTSQRT =>
|
|
v.instr_done := '1';
|
|
v.cr_result := "0000";
|
|
if r.b.class = ZERO or r.b.class = INFINITY or
|
|
(r.b.class = FINITE and r.b.mantissa(UNIT_BIT) = '0') then
|
|
v.cr_result(2) := '1';
|
|
end if;
|
|
if r.b.class = NAN or r.b.class = INFINITY or r.b.class = ZERO
|
|
or r.b.negative = '1' or r.b.exponent <= to_signed(-970, EXP_BITS) then
|
|
v.cr_result(1) := '0';
|
|
end if;
|
|
|
|
when DO_FCMP =>
|
|
-- fcmp[uo]
|
|
-- r.opsel_a = AIN_B
|
|
v.instr_done := '1';
|
|
update_fx := '1';
|
|
re_sel2 <= REXP2_B;
|
|
re_set_result <= '1';
|
|
if (r.a.class = NAN and r.a.mantissa(QNAN_BIT) = '0') or
|
|
(r.b.class = NAN and r.b.mantissa(QNAN_BIT) = '0') then
|
|
-- Signalling NAN
|
|
v.fpscr(FPSCR_VXSNAN) := '1';
|
|
if r.insn(6) = '1' and r.fpscr(FPSCR_VE) = '0' then
|
|
v.fpscr(FPSCR_VXVC) := '1';
|
|
end if;
|
|
invalid := '1';
|
|
v.cr_result := "0001"; -- unordered
|
|
elsif r.a.class = NAN or r.b.class = NAN then
|
|
if r.insn(6) = '1' then
|
|
-- fcmpo
|
|
v.fpscr(FPSCR_VXVC) := '1';
|
|
invalid := '1';
|
|
end if;
|
|
v.cr_result := "0001"; -- unordered
|
|
elsif r.a.class = ZERO and r.b.class = ZERO then
|
|
v.cr_result := "0010"; -- equal
|
|
elsif r.a.negative /= r.b.negative then
|
|
v.cr_result := r.a.negative & r.b.negative & "00";
|
|
elsif r.a.class = ZERO then
|
|
-- A and B are the same sign from here down
|
|
v.cr_result := not r.b.negative & r.b.negative & "00";
|
|
elsif r.a.class = INFINITY then
|
|
if r.b.class = INFINITY then
|
|
v.cr_result := "0010";
|
|
else
|
|
v.cr_result := r.a.negative & not r.a.negative & "00";
|
|
end if;
|
|
elsif r.b.class = ZERO then
|
|
-- A is finite from here down
|
|
v.cr_result := r.a.negative & not r.a.negative & "00";
|
|
elsif r.b.class = INFINITY then
|
|
v.cr_result := not r.b.negative & r.b.negative & "00";
|
|
elsif r.exp_cmp = '1' then
|
|
-- A and B are both finite from here down
|
|
v.cr_result := r.a.negative & not r.a.negative & "00";
|
|
elsif r.a.exponent /= r.b.exponent then
|
|
-- A exponent is smaller than B
|
|
v.cr_result := not r.a.negative & r.a.negative & "00";
|
|
else
|
|
-- Prepare to subtract mantissas, put B in R
|
|
v.cr_result := "0000";
|
|
v.instr_done := '0';
|
|
v.opsel_a := AIN_A;
|
|
v.state := CMP_1;
|
|
end if;
|
|
v.fpscr(FPSCR_FL downto FPSCR_FU) := v.cr_result;
|
|
|
|
when DO_MTFSB =>
|
|
-- mtfsb{0,1}
|
|
j := to_integer(unsigned(insn_bt(r.insn)));
|
|
for i in 0 to 31 loop
|
|
if i = j then
|
|
v.fpscr(31 - i) := r.insn(6);
|
|
end if;
|
|
end loop;
|
|
v.instr_done := '1';
|
|
|
|
when DO_MTFSFI =>
|
|
-- mtfsfi
|
|
j := to_integer(unsigned(insn_bf(r.insn)));
|
|
if r.insn(16) = '0' then
|
|
for i in 0 to 7 loop
|
|
if i = j then
|
|
k := (7 - i) * 4;
|
|
v.fpscr(k + 3 downto k) := insn_u(r.insn);
|
|
end if;
|
|
end loop;
|
|
end if;
|
|
v.instr_done := '1';
|
|
|
|
when DO_FMRG =>
|
|
-- fmrgew, fmrgow
|
|
opsel_r <= RES_MISC;
|
|
misc_sel <= "01" & r.insn(8) & '0';
|
|
int_result := '1';
|
|
v.writing_fpr := '1';
|
|
v.instr_done := '1';
|
|
|
|
when DO_MFFS =>
|
|
v.writing_fpr := '1';
|
|
opsel_r <= RES_MISC;
|
|
case r.insn(20 downto 16) is
|
|
when "00000" =>
|
|
-- mffs
|
|
when "00001" =>
|
|
-- mffsce
|
|
v.fpscr(FPSCR_VE downto FPSCR_XE) := "00000";
|
|
when "10100" | "10101" =>
|
|
-- mffscdrn[i] (but we don't implement DRN)
|
|
fpscr_mask := x"000000FF";
|
|
when "10110" =>
|
|
-- mffscrn
|
|
fpscr_mask := x"000000FF";
|
|
v.fpscr(FPSCR_RN+1 downto FPSCR_RN) :=
|
|
r.b.mantissa(FPSCR_RN+1 downto FPSCR_RN);
|
|
when "10111" =>
|
|
-- mffscrni
|
|
fpscr_mask := x"000000FF";
|
|
v.fpscr(FPSCR_RN+1 downto FPSCR_RN) := r.insn(12 downto 11);
|
|
when "11000" =>
|
|
-- mffsl
|
|
fpscr_mask := x"0007F0FF";
|
|
when others =>
|
|
v.illegal := '1';
|
|
v.writing_fpr := '0';
|
|
end case;
|
|
int_result := '1';
|
|
v.instr_done := '1';
|
|
|
|
when DO_MTFSF =>
|
|
if r.insn(25) = '1' then
|
|
flm := x"FF";
|
|
elsif r.insn(16) = '1' then
|
|
flm := x"00";
|
|
else
|
|
flm := r.insn(24 downto 17);
|
|
end if;
|
|
for i in 0 to 7 loop
|
|
k := i * 4;
|
|
if flm(i) = '1' then
|
|
v.fpscr(k + 3 downto k) := r.b.mantissa(k + 3 downto k);
|
|
end if;
|
|
end loop;
|
|
v.instr_done := '1';
|
|
|
|
when DO_FMR =>
|
|
-- r.opsel_a = AIN_B
|
|
v.result_class := r.b.class;
|
|
re_sel2 <= REXP2_B;
|
|
re_set_result <= '1';
|
|
v.quieten_nan := '0';
|
|
if r.insn(9) = '1' then
|
|
v.result_sign := '0'; -- fabs
|
|
elsif r.insn(8) = '1' then
|
|
v.result_sign := '1'; -- fnabs
|
|
elsif r.insn(7) = '1' then
|
|
v.result_sign := r.b.negative; -- fmr
|
|
elsif r.insn(6) = '1' then
|
|
v.result_sign := not r.b.negative; -- fneg
|
|
else
|
|
v.result_sign := r.a.negative; -- fcpsgn
|
|
end if;
|
|
v.writing_fpr := '1';
|
|
v.instr_done := '1';
|
|
|
|
when DO_FRI => -- fri[nzpm]
|
|
-- r.opsel_a = AIN_B
|
|
v.result_class := r.b.class;
|
|
v.result_sign := r.b.negative;
|
|
re_sel2 <= REXP2_B;
|
|
re_set_result <= '1';
|
|
-- set shift to exponent - 52
|
|
rs_sel1 <= RSH1_B;
|
|
rs_con2 <= RSCON2_52;
|
|
rs_neg2 <= '1';
|
|
v.fpscr(FPSCR_FR) := '0';
|
|
v.fpscr(FPSCR_FI) := '0';
|
|
if r.b.class = NAN and r.b.mantissa(QNAN_BIT) = '0' then
|
|
-- Signalling NAN
|
|
v.fpscr(FPSCR_VXSNAN) := '1';
|
|
invalid := '1';
|
|
end if;
|
|
if r.b.class = FINITE then
|
|
if r.b.exponent >= to_signed(52, EXP_BITS) then
|
|
-- integer already, no rounding required
|
|
arith_done := '1';
|
|
else
|
|
v.state := FRI_1;
|
|
v.round_mode := '1' & r.insn(7 downto 6);
|
|
end if;
|
|
else
|
|
arith_done := '1';
|
|
end if;
|
|
|
|
when DO_FRSP =>
|
|
-- r.opsel_a = AIN_B, r.shift = 0
|
|
v.result_class := r.b.class;
|
|
v.result_sign := r.b.negative;
|
|
re_sel2 <= REXP2_B;
|
|
re_set_result <= '1';
|
|
-- set shift to exponent - -126
|
|
rs_sel1 <= RSH1_B;
|
|
rs_con2 <= RSCON2_MINEXP;
|
|
rs_neg2 <= '1';
|
|
v.fpscr(FPSCR_FR) := '0';
|
|
v.fpscr(FPSCR_FI) := '0';
|
|
if r.b.class = NAN and r.b.mantissa(53) = '0' then
|
|
-- Signalling NAN
|
|
v.fpscr(FPSCR_VXSNAN) := '1';
|
|
invalid := '1';
|
|
end if;
|
|
set_x := '1';
|
|
if r.b.class = FINITE then
|
|
if r.b.exponent < to_signed(-126, EXP_BITS) then
|
|
v.state := ROUND_UFLOW;
|
|
elsif r.b.exponent > to_signed(127, EXP_BITS) then
|
|
v.state := ROUND_OFLOW;
|
|
else
|
|
v.state := ROUNDING;
|
|
end if;
|
|
else
|
|
arith_done := '1';
|
|
end if;
|
|
|
|
when DO_FCTI =>
|
|
-- instr bit 9: 1=dword 0=word
|
|
-- instr bit 8: 1=unsigned 0=signed
|
|
-- instr bit 1: 1=round to zero 0=use fpscr[RN]
|
|
-- r.opsel_a = AIN_B
|
|
v.result_class := r.b.class;
|
|
v.result_sign := r.b.negative;
|
|
re_sel2 <= REXP2_B;
|
|
re_set_result <= '1';
|
|
rs_sel1 <= RSH1_B;
|
|
rs_neg2 <= '1';
|
|
v.fpscr(FPSCR_FR) := '0';
|
|
v.fpscr(FPSCR_FI) := '0';
|
|
if r.b.class = NAN and r.b.mantissa(53) = '0' then
|
|
-- Signalling NAN
|
|
v.fpscr(FPSCR_VXSNAN) := '1';
|
|
invalid := '1';
|
|
end if;
|
|
|
|
int_result := '1';
|
|
|
|
case r.b.class is
|
|
when ZERO =>
|
|
arith_done := '1';
|
|
when FINITE =>
|
|
if r.b.exponent >= to_signed(64, EXP_BITS) or
|
|
(r.insn(9) = '0' and r.b.exponent >= to_signed(32, EXP_BITS)) then
|
|
v.state := INT_OFLOW;
|
|
elsif r.b.exponent >= to_signed(52, EXP_BITS) then
|
|
-- integer already, no rounding required,
|
|
-- shift into final position
|
|
-- set shift to exponent - 56
|
|
rs_con2 <= RSCON2_UNIT;
|
|
if r.insn(8) = '1' and r.b.negative = '1' then
|
|
v.state := INT_OFLOW;
|
|
else
|
|
v.state := INT_ISHIFT;
|
|
end if;
|
|
else
|
|
-- set shift to exponent - 52
|
|
rs_con2 <= RSCON2_52;
|
|
v.state := INT_SHIFT;
|
|
end if;
|
|
when INFINITY | NAN =>
|
|
v.state := INT_OFLOW;
|
|
end case;
|
|
|
|
when DO_FCFID =>
|
|
-- r.opsel_a = AIN_B
|
|
v.result_sign := '0';
|
|
if r.insn(8) = '0' and r.b.negative = '1' then
|
|
-- fcfid[s] with negative operand, set R = -B
|
|
opsel_ainv <= '1';
|
|
carry_in <= '1';
|
|
v.result_sign := '1';
|
|
end if;
|
|
v.result_class := r.b.class;
|
|
re_con2 <= RECON2_UNIT;
|
|
re_set_result <= '1';
|
|
v.fpscr(FPSCR_FR) := '0';
|
|
v.fpscr(FPSCR_FI) := '0';
|
|
if r.b.class = ZERO then
|
|
arith_done := '1';
|
|
else
|
|
v.state := FINISH;
|
|
end if;
|
|
|
|
when DO_FADD =>
|
|
-- fadd[s] and fsub[s]
|
|
-- r.opsel_a = AIN_A
|
|
v.result_sign := r.a.negative;
|
|
v.result_class := r.a.class;
|
|
re_sel1 <= REXP1_A;
|
|
re_set_result <= '1';
|
|
-- set shift to a.exp - b.exp
|
|
rs_sel1 <= RSH1_B;
|
|
rs_neg1 <= '1';
|
|
rs_sel2 <= RSH2_A;
|
|
v.fpscr(FPSCR_FR) := '0';
|
|
v.fpscr(FPSCR_FI) := '0';
|
|
is_add := r.a.negative xor r.b.negative xor r.insn(1);
|
|
v.is_subtract := not is_add;
|
|
if r.a.class = FINITE and r.b.class = FINITE then
|
|
v.add_bsmall := r.exp_cmp;
|
|
v.opsel_a := AIN_B;
|
|
if r.exp_cmp = '0' then
|
|
v.result_sign := r.b.negative xnor r.insn(1);
|
|
if r.a.exponent = r.b.exponent then
|
|
v.state := ADD_2;
|
|
else
|
|
v.longmask := '0';
|
|
v.state := ADD_SHIFT;
|
|
end if;
|
|
else
|
|
v.state := ADD_1;
|
|
end if;
|
|
else
|
|
if r.a.class = NAN or r.b.class = NAN then
|
|
v.state := NAN_RESULT;
|
|
elsif r.a.class = INFINITY and r.b.class = INFINITY and is_add = '0' then
|
|
-- invalid operation, construct QNaN
|
|
v.fpscr(FPSCR_VXISI) := '1';
|
|
qnan_result := '1';
|
|
arith_done := '1';
|
|
elsif r.a.class = INFINITY or r.b.class = ZERO then
|
|
-- result is A; we're already set up to put A into R
|
|
arith_done := '1';
|
|
else
|
|
-- result is +/- B
|
|
v.opsel_a := AIN_B;
|
|
v.result_sign := r.b.negative xnor r.insn(1);
|
|
v.state := EXC_RESULT;
|
|
end if;
|
|
end if;
|
|
|
|
when DO_FMUL =>
|
|
-- fmul[s]
|
|
-- r.opsel_a = AIN_A unless C is denorm and A isn't
|
|
v.result_sign := r.a.negative xor r.c.negative;
|
|
v.result_class := r.a.class;
|
|
v.fpscr(FPSCR_FR) := '0';
|
|
v.fpscr(FPSCR_FI) := '0';
|
|
re_sel1 <= REXP1_A;
|
|
re_sel2 <= REXP2_C;
|
|
re_set_result <= '1';
|
|
if r.a.class = FINITE and r.c.class = FINITE then
|
|
-- Renormalize denorm operands
|
|
if r.a.mantissa(UNIT_BIT) = '0' then
|
|
v.state := RENORM_A;
|
|
elsif r.c.mantissa(UNIT_BIT) = '0' then
|
|
v.state := RENORM_C;
|
|
else
|
|
f_to_multiply.valid <= '1';
|
|
v.state := MULT_1;
|
|
end if;
|
|
else
|
|
if r.a.class = NAN or r.c.class = NAN then
|
|
v.state := NAN_RESULT;
|
|
elsif (r.a.class = INFINITY and r.c.class = ZERO) or
|
|
(r.a.class = ZERO and r.c.class = INFINITY) then
|
|
-- invalid operation, construct QNaN
|
|
v.fpscr(FPSCR_VXIMZ) := '1';
|
|
qnan_result := '1';
|
|
elsif r.a.class = ZERO or r.a.class = INFINITY then
|
|
-- result is +/- A
|
|
arith_done := '1';
|
|
else
|
|
-- r.c.class is ZERO or INFINITY
|
|
v.opsel_a := AIN_C;
|
|
v.state := EXC_RESULT;
|
|
end if;
|
|
end if;
|
|
|
|
when DO_FDIV =>
|
|
-- r.opsel_a = AIN_A unless B is denorm and A isn't
|
|
v.result_class := r.a.class;
|
|
v.fpscr(FPSCR_FR) := '0';
|
|
v.fpscr(FPSCR_FI) := '0';
|
|
v.result_sign := r.a.negative xor r.b.negative;
|
|
re_sel1 <= REXP1_A;
|
|
re_sel2 <= REXP2_B;
|
|
re_neg2 <= '1';
|
|
re_set_result <= '1';
|
|
v.count := "00";
|
|
if r.a.class = FINITE and r.b.class = FINITE then
|
|
-- Renormalize denorm operands
|
|
if r.a.mantissa(UNIT_BIT) = '0' then
|
|
v.state := RENORM_A;
|
|
elsif r.b.mantissa(UNIT_BIT) = '0' then
|
|
v.state := RENORM_B;
|
|
else
|
|
v.first := '1';
|
|
v.state := DIV_2;
|
|
end if;
|
|
else
|
|
if r.a.class = NAN or r.b.class = NAN then
|
|
v.state := NAN_RESULT;
|
|
elsif r.b.class = INFINITY then
|
|
if r.a.class = INFINITY then
|
|
v.fpscr(FPSCR_VXIDI) := '1';
|
|
qnan_result := '1';
|
|
else
|
|
v.result_class := ZERO;
|
|
end if;
|
|
arith_done := '1';
|
|
elsif r.b.class = ZERO then
|
|
if r.a.class = ZERO then
|
|
v.fpscr(FPSCR_VXZDZ) := '1';
|
|
qnan_result := '1';
|
|
else
|
|
if r.a.class = FINITE then
|
|
zero_divide := '1';
|
|
end if;
|
|
v.result_class := INFINITY;
|
|
end if;
|
|
arith_done := '1';
|
|
else -- r.b.class = FINITE, result_class = r.a.class
|
|
arith_done := '1';
|
|
end if;
|
|
end if;
|
|
|
|
when DO_FSEL =>
|
|
v.fpscr(FPSCR_FR) := '0';
|
|
v.fpscr(FPSCR_FI) := '0';
|
|
if r.a.class = ZERO or (r.a.negative = '0' and r.a.class /= NAN) then
|
|
v.opsel_a := AIN_C;
|
|
v.result_sign := r.c.negative;
|
|
else
|
|
v.opsel_a := AIN_B;
|
|
v.result_sign := r.b.negative;
|
|
end if;
|
|
v.quieten_nan := '0';
|
|
v.state := EXC_RESULT;
|
|
|
|
when DO_FSQRT =>
|
|
-- r.opsel_a = AIN_B
|
|
v.result_class := r.b.class;
|
|
v.result_sign := r.b.negative;
|
|
v.fpscr(FPSCR_FR) := '0';
|
|
v.fpscr(FPSCR_FI) := '0';
|
|
re_sel2 <= REXP2_B;
|
|
re_set_result <= '1';
|
|
case r.b.class is
|
|
when FINITE =>
|
|
if r.b.negative = '1' then
|
|
v.fpscr(FPSCR_VXSQRT) := '1';
|
|
qnan_result := '1';
|
|
elsif r.b.mantissa(UNIT_BIT) = '0' then
|
|
v.state := RENORM_B;
|
|
elsif r.b.exponent(0) = '0' then
|
|
v.state := SQRT_1;
|
|
else
|
|
-- set shift to 1
|
|
rs_con2 <= RSCON2_1;
|
|
v.state := RENORM_B2;
|
|
end if;
|
|
when NAN =>
|
|
v.state := NAN_RESULT;
|
|
when ZERO =>
|
|
-- result is B
|
|
arith_done := '1';
|
|
when INFINITY =>
|
|
if r.b.negative = '1' then
|
|
v.fpscr(FPSCR_VXSQRT) := '1';
|
|
qnan_result := '1';
|
|
-- else result is B
|
|
end if;
|
|
arith_done := '1';
|
|
end case;
|
|
|
|
when DO_FRE =>
|
|
-- r.opsel_a = AIN_B
|
|
v.result_class := r.b.class;
|
|
v.result_sign := r.b.negative;
|
|
v.fpscr(FPSCR_FR) := '0';
|
|
v.fpscr(FPSCR_FI) := '0';
|
|
re_sel2 <= REXP2_B;
|
|
re_set_result <= '1';
|
|
case r.b.class is
|
|
when FINITE =>
|
|
if r.b.mantissa(UNIT_BIT) = '0' then
|
|
v.state := RENORM_B;
|
|
else
|
|
v.state := FRE_1;
|
|
end if;
|
|
when NAN =>
|
|
v.state := NAN_RESULT;
|
|
when INFINITY =>
|
|
v.result_class := ZERO;
|
|
arith_done := '1';
|
|
when ZERO =>
|
|
v.result_class := INFINITY;
|
|
zero_divide := '1';
|
|
arith_done := '1';
|
|
end case;
|
|
|
|
when DO_FRSQRTE =>
|
|
-- r.opsel_a = AIN_B
|
|
v.result_class := r.b.class;
|
|
v.result_sign := r.b.negative;
|
|
v.fpscr(FPSCR_FR) := '0';
|
|
v.fpscr(FPSCR_FI) := '0';
|
|
re_sel2 <= REXP2_B;
|
|
re_set_result <= '1';
|
|
-- set shift to 1
|
|
rs_con2 <= RSCON2_1;
|
|
case r.b.class is
|
|
when FINITE =>
|
|
if r.b.negative = '1' then
|
|
v.fpscr(FPSCR_VXSQRT) := '1';
|
|
qnan_result := '1';
|
|
elsif r.b.mantissa(UNIT_BIT) = '0' then
|
|
v.state := RENORM_B;
|
|
elsif r.b.exponent(0) = '0' then
|
|
v.state := RSQRT_1;
|
|
else
|
|
v.state := RENORM_B2;
|
|
end if;
|
|
when NAN =>
|
|
v.state := NAN_RESULT;
|
|
when INFINITY =>
|
|
if r.b.negative = '1' then
|
|
v.fpscr(FPSCR_VXSQRT) := '1';
|
|
qnan_result := '1';
|
|
else
|
|
v.result_class := ZERO;
|
|
end if;
|
|
arith_done := '1';
|
|
when ZERO =>
|
|
v.result_class := INFINITY;
|
|
zero_divide := '1';
|
|
arith_done := '1';
|
|
end case;
|
|
|
|
when DO_FMADD =>
|
|
-- fmadd, fmsub, fnmadd, fnmsub
|
|
-- r.opsel_a = AIN_A if A is denorm, else AIN_C if C is denorm,
|
|
-- else AIN_B
|
|
v.result_sign := r.a.negative;
|
|
v.result_class := r.a.class;
|
|
-- put a.exp + c.exp into result_exp
|
|
re_sel1 <= REXP1_A;
|
|
re_sel2 <= REXP2_C;
|
|
re_set_result <= '1';
|
|
-- put b.exp into shift
|
|
rs_sel1 <= RSH1_B;
|
|
v.fpscr(FPSCR_FR) := '0';
|
|
v.fpscr(FPSCR_FI) := '0';
|
|
is_add := r.a.negative xor r.c.negative xor r.b.negative xor r.insn(1);
|
|
v.negate := r.insn(2);
|
|
v.is_subtract := not is_add;
|
|
if r.a.class = FINITE and r.c.class = FINITE and
|
|
(r.b.class = FINITE or r.b.class = ZERO) then
|
|
-- Make sure A and C are normalized
|
|
if r.a.mantissa(UNIT_BIT) = '0' then
|
|
v.state := RENORM_A;
|
|
elsif r.c.mantissa(UNIT_BIT) = '0' then
|
|
v.state := RENORM_C;
|
|
elsif r.b.class = ZERO then
|
|
-- no addend, degenerates to multiply
|
|
v.result_sign := r.a.negative xor r.c.negative;
|
|
f_to_multiply.valid <= '1';
|
|
v.is_multiply := '1';
|
|
v.state := MULT_1;
|
|
elsif r.madd_cmp = '0' then
|
|
-- addend is bigger, do multiply first
|
|
v.result_sign := r.b.negative xnor r.insn(1);
|
|
f_to_multiply.valid <= '1';
|
|
v.first := '1';
|
|
v.state := FMADD_0;
|
|
else
|
|
-- product is bigger, shift B first
|
|
v.state := FMADD_1;
|
|
end if;
|
|
else
|
|
if r.a.class = NAN or r.b.class = NAN or r.c.class = NAN then
|
|
v.state := NAN_RESULT;
|
|
elsif (r.a.class = ZERO and r.c.class = INFINITY) or
|
|
(r.a.class = INFINITY and r.c.class = ZERO) then
|
|
-- invalid operation, construct QNaN
|
|
v.fpscr(FPSCR_VXIMZ) := '1';
|
|
qnan_result := '1';
|
|
elsif r.a.class = INFINITY or r.c.class = INFINITY then
|
|
if r.b.class = INFINITY and is_add = '0' then
|
|
-- invalid operation, construct QNaN
|
|
v.fpscr(FPSCR_VXISI) := '1';
|
|
qnan_result := '1';
|
|
else
|
|
-- result is infinity
|
|
v.result_class := INFINITY;
|
|
v.result_sign := r.a.negative xor r.c.negative;
|
|
arith_done := '1';
|
|
end if;
|
|
else
|
|
-- Here A is zero, C is zero, or B is infinity
|
|
-- Result is +/-B in all of those cases
|
|
v.opsel_a := AIN_B;
|
|
v.result_sign := r.b.negative xnor r.insn(1);
|
|
v.state := EXC_RESULT;
|
|
end if;
|
|
end if;
|
|
|
|
when RENORM_A =>
|
|
rs_norm <= '1';
|
|
v.state := RENORM_A2;
|
|
if r.use_c = '1' and r.c.denorm = '1' then
|
|
v.opsel_a := AIN_C;
|
|
else
|
|
v.opsel_a := AIN_B;
|
|
end if;
|
|
|
|
when RENORM_A2 =>
|
|
-- r.opsel_a = AIN_C for fmul/fmadd, AIN_B for fdiv
|
|
set_a := '1';
|
|
re_sel2 <= REXP2_NE;
|
|
re_set_result <= '1';
|
|
if r.insn(4) = '1' then
|
|
if r.c.mantissa(UNIT_BIT) = '1' then
|
|
if r.insn(3) = '0' or r.b.class = ZERO then
|
|
v.first := '1';
|
|
v.state := MULT_1;
|
|
else
|
|
v.madd_cmp := '0';
|
|
if new_exp + 1 >= r.b.exponent then
|
|
v.madd_cmp := '1';
|
|
end if;
|
|
v.opsel_a := AIN_B;
|
|
v.state := DO_FMADD;
|
|
end if;
|
|
else
|
|
v.state := RENORM_C;
|
|
end if;
|
|
else
|
|
if r.b.mantissa(UNIT_BIT) = '1' then
|
|
v.first := '1';
|
|
v.state := DIV_2;
|
|
else
|
|
v.state := RENORM_B;
|
|
end if;
|
|
end if;
|
|
|
|
when RENORM_B =>
|
|
rs_norm <= '1';
|
|
renorm_sqrt := r.is_sqrt;
|
|
v.state := RENORM_B2;
|
|
|
|
when RENORM_B2 =>
|
|
set_b := '1';
|
|
re_sel2 <= REXP2_NE;
|
|
re_set_result <= '1';
|
|
v.opsel_a := AIN_B;
|
|
v.state := LOOKUP;
|
|
|
|
when RENORM_C =>
|
|
rs_norm <= '1';
|
|
v.state := RENORM_C2;
|
|
|
|
when RENORM_C2 =>
|
|
set_c := '1';
|
|
re_sel2 <= REXP2_NE;
|
|
re_set_result <= '1';
|
|
if r.insn(3) = '0' or r.b.class = ZERO then
|
|
v.first := '1';
|
|
v.state := MULT_1;
|
|
else
|
|
v.madd_cmp := '0';
|
|
if new_exp + 1 >= r.b.exponent then
|
|
v.madd_cmp := '1';
|
|
end if;
|
|
v.opsel_a := AIN_B;
|
|
v.state := DO_FMADD;
|
|
end if;
|
|
|
|
when ADD_1 =>
|
|
-- transferring B to R
|
|
re_sel2 <= REXP2_B;
|
|
re_set_result <= '1';
|
|
-- set shift to b.exp - a.exp
|
|
rs_sel1 <= RSH1_B;
|
|
rs_sel2 <= RSH2_A;
|
|
rs_neg2 <= '1';
|
|
v.longmask := '0';
|
|
v.state := ADD_SHIFT;
|
|
|
|
when ADD_SHIFT =>
|
|
-- r.shift = - exponent difference, r.longmask = 0
|
|
opsel_r <= RES_SHIFT;
|
|
re_sel2 <= REXP2_NE;
|
|
re_set_result <= '1';
|
|
v.x := s_nz;
|
|
set_x := '1';
|
|
v.longmask := r.single_prec;
|
|
if r.add_bsmall = '1' then
|
|
v.opsel_a := AIN_A;
|
|
else
|
|
v.opsel_a := AIN_B;
|
|
end if;
|
|
v.state := ADD_2;
|
|
|
|
when ADD_2 =>
|
|
-- r.opsel_a = AIN_A if r.add_bsmall = 1 else AIN_B
|
|
opsel_b <= BIN_R;
|
|
opsel_binv <= r.is_subtract;
|
|
carry_in <= r.is_subtract and not r.x;
|
|
-- set shift to -1
|
|
rs_con2 <= RSCON2_1;
|
|
rs_neg2 <= '1';
|
|
v.state := ADD_3;
|
|
|
|
when ADD_3 =>
|
|
-- check for overflow or negative result (can't get both)
|
|
-- r.shift = -1
|
|
re_sel2 <= REXP2_NE;
|
|
if r.r(63) = '1' then
|
|
-- result is opposite sign to expected
|
|
v.result_sign := not r.result_sign;
|
|
opsel_ainv <= '1';
|
|
carry_in <= '1';
|
|
v.state := FINISH;
|
|
elsif r.r(UNIT_BIT + 1) = '1' then
|
|
-- sum overflowed, shift right
|
|
opsel_r <= RES_SHIFT;
|
|
re_set_result <= '1';
|
|
set_x := '1';
|
|
if exp_huge = '1' then
|
|
v.state := ROUND_OFLOW;
|
|
else
|
|
v.state := ROUNDING;
|
|
end if;
|
|
elsif r.r(UNIT_BIT) = '1' then
|
|
set_x := '1';
|
|
v.state := ROUNDING;
|
|
elsif (r_hi_nz or r_lo_nz or (or (r.r(DP_LSB - 1 downto 0)))) = '0' then
|
|
-- r.x must be zero at this point
|
|
v.result_class := ZERO;
|
|
arith_done := '1';
|
|
else
|
|
rs_norm <= '1';
|
|
v.state := NORMALIZE;
|
|
end if;
|
|
|
|
when CMP_1 =>
|
|
-- r.opsel_a = AIN_A
|
|
opsel_b <= BIN_R;
|
|
opsel_binv <= '1';
|
|
carry_in <= '1';
|
|
v.state := CMP_2;
|
|
|
|
when CMP_2 =>
|
|
if r.r(63) = '1' then
|
|
-- A is smaller in magnitude
|
|
v.cr_result := not r.a.negative & r.a.negative & "00";
|
|
elsif (r_hi_nz or r_lo_nz) = '0' then
|
|
v.cr_result := "0010";
|
|
else
|
|
v.cr_result := r.a.negative & not r.a.negative & "00";
|
|
end if;
|
|
v.fpscr(FPSCR_FL downto FPSCR_FU) := v.cr_result;
|
|
v.instr_done := '1';
|
|
|
|
when MULT_1 =>
|
|
f_to_multiply.valid <= r.first;
|
|
opsel_r <= RES_MULT;
|
|
if multiply_to_f.valid = '1' then
|
|
v.state := FINISH;
|
|
end if;
|
|
|
|
when FMADD_0 =>
|
|
-- r.shift is b.exp, so new_exp is a.exp + c.exp - b.exp
|
|
-- (first time through; subsequent times we preserve v.shift)
|
|
-- Addend is bigger here
|
|
-- set shift to a.exp + c.exp - b.exp
|
|
-- note v.shift is at most -2 here
|
|
if r.first = '1' then
|
|
rs_sel1 <= RSH1_NE;
|
|
else
|
|
rs_sel1 <= RSH1_S;
|
|
end if;
|
|
opsel_r <= RES_MULT;
|
|
opsel_s <= S_MULT;
|
|
set_s := '1';
|
|
if multiply_to_f.valid = '1' then
|
|
v.longmask := '0';
|
|
v.state := ADD_SHIFT;
|
|
end if;
|
|
|
|
when FMADD_1 =>
|
|
-- shift is b.exp, so new_exp is a.exp + c.exp - b.exp
|
|
-- product is bigger here
|
|
-- shift B right and use it as the addend to the multiplier
|
|
-- for subtract, multiplier does B - A * C
|
|
v.result_sign := r.a.negative xor r.c.negative xor r.is_subtract;
|
|
re_sel2 <= REXP2_B;
|
|
re_set_result <= '1';
|
|
-- set shift to b.exp - result_exp + 64
|
|
rs_sel1 <= RSH1_NE;
|
|
rs_neg1 <= '1';
|
|
rs_con2 <= RSCON2_64;
|
|
v.state := FMADD_2;
|
|
|
|
when FMADD_2 =>
|
|
-- Product is potentially bigger here
|
|
-- r.shift = addend exp - product exp + 64, r.r = r.b.mantissa
|
|
set_s := '1';
|
|
opsel_s <= S_SHIFT;
|
|
-- set shift to r.shift - 64
|
|
rs_sel1 <= RSH1_S;
|
|
rs_con2 <= RSCON2_64;
|
|
rs_neg2 <= '1';
|
|
v.state := FMADD_3;
|
|
|
|
when FMADD_3 =>
|
|
-- r.shift = addend exp - product exp
|
|
opsel_r <= RES_SHIFT;
|
|
re_sel2 <= REXP2_NE;
|
|
re_set_result <= '1';
|
|
v.first := '1';
|
|
v.state := FMADD_4;
|
|
|
|
when FMADD_4 =>
|
|
msel_add <= MULADD_RS;
|
|
f_to_multiply.valid <= r.first;
|
|
msel_inv <= r.is_subtract;
|
|
opsel_r <= RES_MULT;
|
|
opsel_s <= S_MULT;
|
|
set_s := '1';
|
|
if multiply_to_f.valid = '1' then
|
|
v.state := FMADD_5;
|
|
end if;
|
|
|
|
when FMADD_5 =>
|
|
-- negate R:S:X if negative
|
|
if r.r(63) = '1' then
|
|
v.result_sign := not r.result_sign;
|
|
opsel_ainv <= '1';
|
|
carry_in <= not (s_nz or r.x);
|
|
opsel_s <= S_NEG;
|
|
set_s := '1';
|
|
end if;
|
|
-- set shift to UNIT_BIT
|
|
rs_con2 <= RSCON2_UNIT;
|
|
v.state := FMADD_6;
|
|
|
|
when FMADD_6 =>
|
|
-- r.shift = UNIT_BIT (or 0, but only if r is now nonzero)
|
|
re_sel2 <= REXP2_NE;
|
|
rs_norm <= '1';
|
|
if (r.r(UNIT_BIT + 2) or r_hi_nz or r_lo_nz or (or (r.r(DP_LSB - 1 downto 0)))) = '0' then
|
|
if s_nz = '0' then
|
|
-- must be a subtraction, and r.x must be zero
|
|
v.result_class := ZERO;
|
|
arith_done := '1';
|
|
else
|
|
-- R is all zeroes but there are non-zero bits in S
|
|
-- so shift them into R and set S to 0
|
|
opsel_r <= RES_SHIFT;
|
|
re_set_result <= '1';
|
|
set_s := '1';
|
|
v.state := FINISH;
|
|
end if;
|
|
elsif r.r(UNIT_BIT + 2 downto UNIT_BIT) = "001" then
|
|
v.state := FINISH;
|
|
else
|
|
v.state := NORMALIZE;
|
|
end if;
|
|
|
|
when LOOKUP =>
|
|
-- r.opsel_a = AIN_B
|
|
-- wait one cycle for inverse_table[B] lookup
|
|
v.first := '1';
|
|
if r.insn(4) = '0' then
|
|
if r.insn(3) = '0' then
|
|
v.state := DIV_2;
|
|
else
|
|
v.state := SQRT_1;
|
|
end if;
|
|
elsif r.insn(2) = '0' then
|
|
v.state := FRE_1;
|
|
else
|
|
v.state := RSQRT_1;
|
|
end if;
|
|
|
|
when DIV_2 =>
|
|
-- compute Y = inverse_table[B] (when count=0); P = 2 - B * Y
|
|
msel_1 <= MUL1_B;
|
|
msel_add <= MULADD_CONST;
|
|
msel_inv <= '1';
|
|
if r.count = 0 then
|
|
msel_2 <= MUL2_LUT;
|
|
else
|
|
msel_2 <= MUL2_P;
|
|
end if;
|
|
set_y := r.first;
|
|
pshift := '1';
|
|
f_to_multiply.valid <= r.first;
|
|
if multiply_to_f.valid = '1' then
|
|
v.first := '1';
|
|
v.count := r.count + 1;
|
|
v.state := DIV_3;
|
|
end if;
|
|
|
|
when DIV_3 =>
|
|
-- compute Y = P = P * Y
|
|
msel_1 <= MUL1_Y;
|
|
msel_2 <= MUL2_P;
|
|
f_to_multiply.valid <= r.first;
|
|
pshift := '1';
|
|
if multiply_to_f.valid = '1' then
|
|
v.first := '1';
|
|
if r.count = 3 then
|
|
v.state := DIV_4;
|
|
else
|
|
v.state := DIV_2;
|
|
end if;
|
|
end if;
|
|
|
|
when DIV_4 =>
|
|
-- compute R = P = A * Y (quotient)
|
|
msel_1 <= MUL1_A;
|
|
msel_2 <= MUL2_P;
|
|
set_y := r.first;
|
|
f_to_multiply.valid <= r.first;
|
|
pshift := '1';
|
|
mult_mask := '1';
|
|
if multiply_to_f.valid = '1' then
|
|
opsel_r <= RES_MULT;
|
|
v.first := '1';
|
|
v.state := DIV_5;
|
|
end if;
|
|
|
|
when DIV_5 =>
|
|
-- compute P = A - B * R (remainder)
|
|
msel_1 <= MUL1_B;
|
|
msel_2 <= MUL2_R;
|
|
msel_add <= MULADD_A;
|
|
msel_inv <= '1';
|
|
f_to_multiply.valid <= r.first;
|
|
if multiply_to_f.valid = '1' then
|
|
v.state := DIV_6;
|
|
end if;
|
|
|
|
when DIV_6 =>
|
|
-- r.opsel_a = AIN_R
|
|
-- test if remainder is 0 or >= B
|
|
if pcmpb_lt = '1' then
|
|
-- quotient is correct, set X if remainder non-zero
|
|
v.x := r.p(UNIT_BIT + 2) or px_nz;
|
|
else
|
|
-- quotient needs to be incremented by 1 in R-bit position
|
|
rbit_inc := '1';
|
|
opsel_b <= BIN_RND;
|
|
v.x := not pcmpb_eq;
|
|
end if;
|
|
v.state := FINISH;
|
|
|
|
when FRE_1 =>
|
|
re_sel1 <= REXP1_R;
|
|
re_neg1 <= '1';
|
|
re_set_result <= '1';
|
|
opsel_r <= RES_MISC;
|
|
misc_sel <= "0111";
|
|
-- set shift to 1
|
|
rs_con2 <= RSCON2_1;
|
|
v.state := NORMALIZE;
|
|
|
|
when FTDIV_1 =>
|
|
v.cr_result(1) := exp_tiny or exp_huge;
|
|
-- set shift to a.exp
|
|
rs_sel2 <= RSH2_A;
|
|
if exp_tiny = '1' or exp_huge = '1' or r.a.class = ZERO or r.first = '0' then
|
|
v.instr_done := '1';
|
|
else
|
|
v.doing_ftdiv := "10";
|
|
end if;
|
|
|
|
when RSQRT_1 =>
|
|
opsel_r <= RES_MISC;
|
|
misc_sel <= "0111";
|
|
re_sel1 <= REXP1_BHALF;
|
|
re_neg1 <= '1';
|
|
re_set_result <= '1';
|
|
-- set shift to 1
|
|
rs_con2 <= RSCON2_1;
|
|
v.state := NORMALIZE;
|
|
|
|
when SQRT_1 =>
|
|
-- put invsqr[B] in R and compute P = invsqr[B] * B
|
|
-- also transfer B (in R) to A
|
|
set_a := '1';
|
|
opsel_r <= RES_MISC;
|
|
misc_sel <= "0111";
|
|
msel_1 <= MUL1_B;
|
|
msel_2 <= MUL2_LUT;
|
|
f_to_multiply.valid <= '1';
|
|
-- set shift to -1
|
|
rs_con2 <= RSCON2_1;
|
|
rs_neg2 <= '1';
|
|
v.count := "00";
|
|
v.state := SQRT_2;
|
|
|
|
when SQRT_2 =>
|
|
-- shift R right one place
|
|
-- not expecting multiplier result yet
|
|
-- r.shift = -1
|
|
opsel_r <= RES_SHIFT;
|
|
re_sel2 <= REXP2_NE;
|
|
re_set_result <= '1';
|
|
v.first := '1';
|
|
v.state := SQRT_3;
|
|
|
|
when SQRT_3 =>
|
|
-- put R into Y, wait for product from multiplier
|
|
msel_2 <= MUL2_R;
|
|
set_y := r.first;
|
|
pshift := '1';
|
|
mult_mask := '1';
|
|
if multiply_to_f.valid = '1' then
|
|
-- put result into R
|
|
opsel_r <= RES_MULT;
|
|
v.first := '1';
|
|
v.state := SQRT_4;
|
|
end if;
|
|
|
|
when SQRT_4 =>
|
|
-- compute 1.5 - Y * P
|
|
msel_1 <= MUL1_Y;
|
|
msel_2 <= MUL2_P;
|
|
msel_add <= MULADD_CONST;
|
|
msel_inv <= '1';
|
|
f_to_multiply.valid <= r.first;
|
|
pshift := '1';
|
|
if multiply_to_f.valid = '1' then
|
|
v.state := SQRT_5;
|
|
end if;
|
|
|
|
when SQRT_5 =>
|
|
-- compute Y = Y * P
|
|
msel_1 <= MUL1_Y;
|
|
msel_2 <= MUL2_P;
|
|
f_to_multiply.valid <= '1';
|
|
v.first := '1';
|
|
v.state := SQRT_6;
|
|
|
|
when SQRT_6 =>
|
|
-- pipeline in R = R * P
|
|
msel_1 <= MUL1_R;
|
|
msel_2 <= MUL2_P;
|
|
f_to_multiply.valid <= r.first;
|
|
pshift := '1';
|
|
if multiply_to_f.valid = '1' then
|
|
v.first := '1';
|
|
v.state := SQRT_7;
|
|
end if;
|
|
|
|
when SQRT_7 =>
|
|
-- first multiply is done, put result in Y
|
|
msel_2 <= MUL2_P;
|
|
set_y := r.first;
|
|
-- wait for second multiply (should be here already)
|
|
pshift := '1';
|
|
mult_mask := '1';
|
|
if multiply_to_f.valid = '1' then
|
|
-- put result into R
|
|
opsel_r <= RES_MULT;
|
|
v.first := '1';
|
|
v.count := r.count + 1;
|
|
if r.count < 2 then
|
|
v.state := SQRT_4;
|
|
else
|
|
v.first := '1';
|
|
v.state := SQRT_8;
|
|
end if;
|
|
end if;
|
|
|
|
when SQRT_8 =>
|
|
-- compute P = A - R * R, which can be +ve or -ve
|
|
-- we arranged for B to be put into A earlier
|
|
msel_1 <= MUL1_R;
|
|
msel_2 <= MUL2_R;
|
|
msel_add <= MULADD_A;
|
|
msel_inv <= '1';
|
|
pshift := '1';
|
|
f_to_multiply.valid <= r.first;
|
|
if multiply_to_f.valid = '1' then
|
|
v.first := '1';
|
|
v.state := SQRT_9;
|
|
end if;
|
|
|
|
when SQRT_9 =>
|
|
-- compute P = P * Y
|
|
-- since Y is an estimate of 1/sqrt(B), this makes P an
|
|
-- estimate of the adjustment needed to R. Since the error
|
|
-- could be negative and we have an unsigned multiplier, the
|
|
-- upper bits can be wrong, but it turns out the lowest 8 bits
|
|
-- are correct and are all we need (given 3 iterations through
|
|
-- SQRT_4 to SQRT_7).
|
|
msel_1 <= MUL1_Y;
|
|
msel_2 <= MUL2_P;
|
|
pshift := '1';
|
|
f_to_multiply.valid <= r.first;
|
|
if multiply_to_f.valid = '1' then
|
|
v.state := SQRT_10;
|
|
end if;
|
|
|
|
when SQRT_10 =>
|
|
-- Add the bottom 8 bits of P, sign-extended, onto R.
|
|
opsel_b <= BIN_PS8;
|
|
re_sel1 <= REXP1_BHALF;
|
|
re_set_result <= '1';
|
|
-- set shift to 1
|
|
rs_con2 <= RSCON2_1;
|
|
v.first := '1';
|
|
v.state := SQRT_11;
|
|
|
|
when SQRT_11 =>
|
|
-- compute P = A - R * R (remainder)
|
|
-- also put 2 * R + 1 into B for comparison with P
|
|
msel_1 <= MUL1_R;
|
|
msel_2 <= MUL2_R;
|
|
msel_add <= MULADD_A;
|
|
msel_inv <= '1';
|
|
f_to_multiply.valid <= r.first;
|
|
shiftin := '1';
|
|
set_b := r.first;
|
|
if multiply_to_f.valid = '1' then
|
|
v.state := SQRT_12;
|
|
end if;
|
|
|
|
when SQRT_12 =>
|
|
-- test if remainder is 0 or >= B = 2*R + 1
|
|
if pcmpb_lt = '1' then
|
|
-- square root is correct, set X if remainder non-zero
|
|
v.x := r.p(UNIT_BIT + 2) or px_nz;
|
|
else
|
|
-- square root needs to be incremented by 1
|
|
carry_in <= '1';
|
|
v.x := not pcmpb_eq;
|
|
end if;
|
|
v.state := FINISH;
|
|
|
|
when INT_SHIFT =>
|
|
-- r.shift = b.exponent - 52
|
|
opsel_r <= RES_SHIFT;
|
|
re_sel2 <= REXP2_NE;
|
|
re_set_result <= '1';
|
|
set_x := '1';
|
|
v.state := INT_ROUND;
|
|
-- set shift to -4 (== 52 - UNIT_BIT)
|
|
rs_con2 <= RSCON2_UNIT_52;
|
|
rs_neg2 <= '1';
|
|
|
|
when INT_ROUND =>
|
|
-- r.shift = -4 (== 52 - UNIT_BIT)
|
|
opsel_r <= RES_SHIFT;
|
|
re_sel2 <= REXP2_NE;
|
|
re_set_result <= '1';
|
|
round := fp_rounding(r.r, r.x, '0', r.round_mode, r.result_sign);
|
|
v.fpscr(FPSCR_FR downto FPSCR_FI) := round;
|
|
-- Check for negative values that don't round to 0 for fcti*u*
|
|
if r.insn(8) = '1' and r.result_sign = '1' and
|
|
(r_hi_nz or r_lo_nz or v.fpscr(FPSCR_FR)) = '1' then
|
|
v.state := INT_OFLOW;
|
|
else
|
|
v.state := INT_FINAL;
|
|
end if;
|
|
|
|
when INT_ISHIFT =>
|
|
-- r.shift = b.exponent - UNIT_BIT;
|
|
opsel_r <= RES_SHIFT;
|
|
re_sel2 <= REXP2_NE;
|
|
re_set_result <= '1';
|
|
v.state := INT_FINAL;
|
|
|
|
when INT_FINAL =>
|
|
-- Negate if necessary, and increment for rounding if needed
|
|
opsel_ainv <= r.result_sign;
|
|
carry_in <= r.fpscr(FPSCR_FR) xor r.result_sign;
|
|
-- Check for possible overflows
|
|
case r.insn(9 downto 8) is
|
|
when "00" => -- fctiw[z]
|
|
need_check := r.r(31) or (r.r(30) and not r.result_sign);
|
|
when "01" => -- fctiwu[z]
|
|
need_check := r.r(31);
|
|
when "10" => -- fctid[z]
|
|
need_check := r.r(63) or (r.r(62) and not r.result_sign);
|
|
when others => -- fctidu[z]
|
|
need_check := r.r(63);
|
|
end case;
|
|
int_result := '1';
|
|
if need_check = '1' then
|
|
v.state := INT_CHECK;
|
|
else
|
|
if r.fpscr(FPSCR_FI) = '1' then
|
|
v.fpscr(FPSCR_XX) := '1';
|
|
end if;
|
|
arith_done := '1';
|
|
end if;
|
|
|
|
when INT_CHECK =>
|
|
if r.insn(9) = '0' then
|
|
msb := r.r(31);
|
|
else
|
|
msb := r.r(63);
|
|
end if;
|
|
misc_sel <= '1' & r.insn(9 downto 8) & r.result_sign;
|
|
if (r.insn(8) = '0' and msb /= r.result_sign) or
|
|
(r.insn(8) = '1' and msb /= '1') then
|
|
opsel_r <= RES_MISC;
|
|
v.fpscr(FPSCR_VXCVI) := '1';
|
|
invalid := '1';
|
|
else
|
|
if r.fpscr(FPSCR_FI) = '1' then
|
|
v.fpscr(FPSCR_XX) := '1';
|
|
end if;
|
|
end if;
|
|
int_result := '1';
|
|
arith_done := '1';
|
|
|
|
when INT_OFLOW =>
|
|
opsel_r <= RES_MISC;
|
|
misc_sel <= '1' & r.insn(9 downto 8) & r.result_sign;
|
|
if r.b.class = NAN then
|
|
misc_sel(0) <= '1';
|
|
end if;
|
|
v.fpscr(FPSCR_VXCVI) := '1';
|
|
invalid := '1';
|
|
int_result := '1';
|
|
arith_done := '1';
|
|
|
|
when FRI_1 =>
|
|
-- r.shift = b.exponent - 52
|
|
opsel_r <= RES_SHIFT;
|
|
re_sel2 <= REXP2_NE;
|
|
re_set_result <= '1';
|
|
set_x := '1';
|
|
v.state := ROUNDING;
|
|
|
|
when FINISH =>
|
|
if r.is_multiply = '1' and px_nz = '1' then
|
|
v.x := '1';
|
|
end if;
|
|
-- set shift to new_exp - min_exp (N.B. rs_norm overrides this)
|
|
rs_sel1 <= RSH1_NE;
|
|
rs_con2 <= RSCON2_MINEXP;
|
|
rs_neg2 <= '1';
|
|
if r.r(63 downto UNIT_BIT) /= std_ulogic_vector(to_unsigned(1, 64 - UNIT_BIT)) then
|
|
rs_norm <= '1';
|
|
v.state := NORMALIZE;
|
|
else
|
|
set_x := '1';
|
|
if exp_tiny = '1' then
|
|
v.state := ROUND_UFLOW;
|
|
elsif exp_huge = '1' then
|
|
v.state := ROUND_OFLOW;
|
|
else
|
|
v.state := ROUNDING;
|
|
end if;
|
|
end if;
|
|
|
|
when NORMALIZE =>
|
|
-- Shift so we have 9 leading zeroes (we know R is non-zero)
|
|
-- r.shift = clz(r.r) - 7
|
|
opsel_r <= RES_SHIFT;
|
|
re_sel2 <= REXP2_NE;
|
|
re_set_result <= '1';
|
|
-- set shift to new_exp - min_exp
|
|
rs_sel1 <= RSH1_NE;
|
|
rs_con2 <= RSCON2_MINEXP;
|
|
rs_neg2 <= '1';
|
|
set_x := '1';
|
|
if exp_tiny = '1' then
|
|
v.state := ROUND_UFLOW;
|
|
elsif exp_huge = '1' then
|
|
v.state := ROUND_OFLOW;
|
|
else
|
|
v.state := ROUNDING;
|
|
end if;
|
|
|
|
when ROUND_UFLOW =>
|
|
-- r.shift = - amount by which exponent underflows
|
|
v.tiny := '1';
|
|
if r.fpscr(FPSCR_UE) = '0' then
|
|
-- disabled underflow exception case
|
|
-- have to denormalize before rounding
|
|
opsel_r <= RES_SHIFT;
|
|
re_sel2 <= REXP2_NE;
|
|
re_set_result <= '1';
|
|
set_x := '1';
|
|
v.state := ROUNDING;
|
|
else
|
|
-- enabled underflow exception case
|
|
-- if denormalized, have to normalize before rounding
|
|
v.fpscr(FPSCR_UX) := '1';
|
|
re_sel1 <= REXP1_R;
|
|
re_con2 <= RECON2_BIAS;
|
|
re_set_result <= '1';
|
|
if r.r(UNIT_BIT) = '0' then
|
|
rs_norm <= '1';
|
|
v.state := NORMALIZE;
|
|
else
|
|
v.state := ROUNDING;
|
|
end if;
|
|
end if;
|
|
|
|
when ROUND_OFLOW =>
|
|
v.fpscr(FPSCR_OX) := '1';
|
|
if r.fpscr(FPSCR_OE) = '0' then
|
|
-- disabled overflow exception
|
|
-- result depends on rounding mode
|
|
v.fpscr(FPSCR_XX) := '1';
|
|
v.fpscr(FPSCR_FI) := '1';
|
|
if r.round_mode(1 downto 0) = "00" or
|
|
(r.round_mode(1) = '1' and r.round_mode(0) = r.result_sign) then
|
|
v.result_class := INFINITY;
|
|
v.fpscr(FPSCR_FR) := '1';
|
|
else
|
|
v.fpscr(FPSCR_FR) := '0';
|
|
end if;
|
|
-- construct largest representable number
|
|
re_con2 <= RECON2_MAX;
|
|
re_set_result <= '1';
|
|
opsel_r <= RES_MISC;
|
|
misc_sel <= "001" & r.single_prec;
|
|
arith_done := '1';
|
|
else
|
|
-- enabled overflow exception
|
|
re_sel1 <= REXP1_R;
|
|
re_con2 <= RECON2_BIAS;
|
|
re_neg2 <= '1';
|
|
re_set_result <= '1';
|
|
v.state := ROUNDING;
|
|
end if;
|
|
|
|
when ROUNDING =>
|
|
opsel_mask <= '1';
|
|
round := fp_rounding(r.r, r.x, r.single_prec, r.round_mode, r.result_sign);
|
|
v.fpscr(FPSCR_FR downto FPSCR_FI) := round;
|
|
if round(1) = '1' then
|
|
-- increment the LSB for the precision
|
|
opsel_b <= BIN_RND;
|
|
-- set shift to -1
|
|
rs_con2 <= RSCON2_1;
|
|
rs_neg2 <= '1';
|
|
v.state := ROUNDING_2;
|
|
else
|
|
if r.r(UNIT_BIT) = '0' then
|
|
-- result after masking could be zero, or could be a
|
|
-- denormalized result that needs to be renormalized
|
|
rs_norm <= '1';
|
|
v.state := ROUNDING_3;
|
|
else
|
|
arith_done := '1';
|
|
end if;
|
|
end if;
|
|
if round(0) = '1' then
|
|
v.fpscr(FPSCR_XX) := '1';
|
|
if r.tiny = '1' then
|
|
v.fpscr(FPSCR_UX) := '1';
|
|
end if;
|
|
end if;
|
|
|
|
when ROUNDING_2 =>
|
|
-- Check for overflow during rounding
|
|
-- r.shift = -1
|
|
v.x := '0';
|
|
re_sel2 <= REXP2_NE;
|
|
if r.r(UNIT_BIT + 1) = '1' then
|
|
opsel_r <= RES_SHIFT;
|
|
re_set_result <= '1';
|
|
if exp_huge = '1' then
|
|
v.state := ROUND_OFLOW;
|
|
else
|
|
arith_done := '1';
|
|
end if;
|
|
elsif r.r(UNIT_BIT) = '0' then
|
|
-- Do CLZ so we can renormalize the result
|
|
rs_norm <= '1';
|
|
v.state := ROUNDING_3;
|
|
else
|
|
arith_done := '1';
|
|
end if;
|
|
|
|
when ROUNDING_3 =>
|
|
-- r.shift = clz(r.r) - 9
|
|
mant_nz := r_hi_nz or (r_lo_nz and not r.single_prec);
|
|
re_sel2 <= REXP2_NE;
|
|
-- set shift to new_exp - min_exp (== -1022)
|
|
rs_sel1 <= RSH1_NE;
|
|
rs_con2 <= RSCON2_MINEXP;
|
|
rs_neg2 <= '1';
|
|
if mant_nz = '0' then
|
|
v.result_class := ZERO;
|
|
arith_done := '1';
|
|
else
|
|
-- Renormalize result after rounding
|
|
opsel_r <= RES_SHIFT;
|
|
re_set_result <= '1';
|
|
v.denorm := exp_tiny;
|
|
if new_exp < to_signed(-1022, EXP_BITS) then
|
|
v.state := DENORM;
|
|
else
|
|
arith_done := '1';
|
|
end if;
|
|
end if;
|
|
|
|
when DENORM =>
|
|
-- r.shift = result_exp - -1022
|
|
opsel_r <= RES_SHIFT;
|
|
re_sel2 <= REXP2_NE;
|
|
re_set_result <= '1';
|
|
arith_done := '1';
|
|
|
|
when NAN_RESULT =>
|
|
v.negate := '0';
|
|
if (r.use_a = '1' and r.a.class = NAN and r.a.mantissa(QNAN_BIT) = '0') or
|
|
(r.use_b = '1' and r.b.class = NAN and r.b.mantissa(QNAN_BIT) = '0') or
|
|
(r.use_c = '1' and r.c.class = NAN and r.c.mantissa(QNAN_BIT) = '0') then
|
|
-- Signalling NAN
|
|
v.fpscr(FPSCR_VXSNAN) := '1';
|
|
invalid := '1';
|
|
end if;
|
|
if r.use_a = '1' and r.a.class = NAN then
|
|
v.opsel_a := AIN_A;
|
|
v.result_sign := r.a.negative;
|
|
elsif r.use_b = '1' and r.b.class = NAN then
|
|
v.opsel_a := AIN_B;
|
|
v.result_sign := r.b.negative;
|
|
elsif r.use_c = '1' and r.c.class = NAN then
|
|
v.opsel_a := AIN_C;
|
|
v.result_sign := r.c.negative;
|
|
end if;
|
|
v.state := EXC_RESULT;
|
|
|
|
when EXC_RESULT =>
|
|
-- r.opsel_a = AIN_A, AIN_B or AIN_C according to which input is the result
|
|
case r.opsel_a is
|
|
when AIN_B =>
|
|
re_sel2 <= REXP2_B;
|
|
v.result_class := r.b.class;
|
|
when AIN_C =>
|
|
re_sel2 <= REXP2_C;
|
|
v.result_class := r.c.class;
|
|
when others =>
|
|
re_sel1 <= REXP1_A;
|
|
v.result_class := r.a.class;
|
|
end case;
|
|
re_set_result <= '1';
|
|
arith_done := '1';
|
|
|
|
when DO_IDIVMOD =>
|
|
-- r.opsel_a = AIN_B
|
|
v.result_sign := r.is_signed and (r.a.negative xor (r.b.negative and not r.divmod));
|
|
if r.b.class = ZERO then
|
|
-- B is zero, signal overflow
|
|
v.int_ovf := '1';
|
|
v.state := IDIV_ZERO;
|
|
elsif r.a.class = ZERO then
|
|
-- A is zero, result is zero (both for div and for mod)
|
|
v.state := IDIV_ZERO;
|
|
else
|
|
-- take absolute value for signed division, and
|
|
-- normalize and round up B to 8.56 format, like fcfid[u]
|
|
if r.is_signed = '1' and r.b.negative = '1' then
|
|
opsel_ainv <= '1';
|
|
carry_in <= '1';
|
|
end if;
|
|
v.result_class := FINITE;
|
|
re_con2 <= RECON2_UNIT;
|
|
re_set_result <= '1';
|
|
v.state := IDIV_NORMB;
|
|
end if;
|
|
when IDIV_NORMB =>
|
|
-- do count-leading-zeroes on B (now in R)
|
|
rs_norm <= '1';
|
|
-- save the original value of B or |B| in C
|
|
set_c := '1';
|
|
v.state := IDIV_NORMB2;
|
|
when IDIV_NORMB2 =>
|
|
-- get B into the range [1, 2) in 8.56 format
|
|
set_x := '1'; -- record if any 1 bits shifted out
|
|
opsel_r <= RES_SHIFT;
|
|
re_sel2 <= REXP2_NE;
|
|
re_set_result <= '1';
|
|
v.state := IDIV_NORMB3;
|
|
when IDIV_NORMB3 =>
|
|
-- add the X bit onto R to round up B
|
|
carry_in <= r.x;
|
|
-- prepare to do count-leading-zeroes on A
|
|
v.opsel_a := AIN_A;
|
|
v.state := IDIV_CLZA;
|
|
when IDIV_CLZA =>
|
|
set_b := '1'; -- put R back into B
|
|
-- r.opsel_a = AIN_A
|
|
if r.is_signed = '1' and r.a.negative = '1' then
|
|
opsel_ainv <= '1';
|
|
carry_in <= '1';
|
|
end if;
|
|
re_con2 <= RECON2_UNIT;
|
|
re_set_result <= '1';
|
|
v.opsel_a := AIN_C;
|
|
v.state := IDIV_CLZA2;
|
|
when IDIV_CLZA2 =>
|
|
-- r.opsel_a = AIN_C
|
|
rs_norm <= '1';
|
|
-- write the dividend back into A in case we negated it
|
|
set_a_mant := '1';
|
|
-- while doing the count-leading-zeroes on A,
|
|
-- also compute A - B to tell us whether A >= B
|
|
-- (using the original value of B, which is now in C)
|
|
opsel_b <= BIN_R;
|
|
opsel_ainv <= '1';
|
|
carry_in <= '1';
|
|
v.state := IDIV_CLZA3;
|
|
when IDIV_CLZA3 =>
|
|
-- save the exponent of A (but don't overwrite the mantissa)
|
|
set_a_exp := '1';
|
|
re_sel2 <= REXP2_NE;
|
|
re_set_result <= '1';
|
|
v.div_close := '0';
|
|
if new_exp = r.b.exponent then
|
|
v.div_close := '1';
|
|
end if;
|
|
v.state := IDIV_NR0;
|
|
if new_exp > r.b.exponent or (v.div_close = '1' and r.r(63) = '0') then
|
|
-- A >= B, overflow if extended division
|
|
if r.divext = '1' then
|
|
v.int_ovf := '1';
|
|
-- return 0 in overflow cases
|
|
v.state := IDIV_ZERO;
|
|
end if;
|
|
else
|
|
-- A < B, result is zero for normal division
|
|
if r.divmod = '0' and r.divext = '0' then
|
|
v.state := IDIV_ZERO;
|
|
end if;
|
|
end if;
|
|
when IDIV_NR0 =>
|
|
-- reduce number of Newton-Raphson iterations for small A
|
|
if r.divext = '1' or r.result_exp >= to_signed(32, EXP_BITS) then
|
|
v.count := "00";
|
|
elsif r.result_exp >= to_signed(16, EXP_BITS) then
|
|
v.count := "01";
|
|
else
|
|
v.count := "10";
|
|
end if;
|
|
-- first NR iteration does Y = LUT; P = 2 - B * LUT
|
|
msel_1 <= MUL1_B;
|
|
msel_add <= MULADD_CONST;
|
|
msel_inv <= '1';
|
|
msel_2 <= MUL2_LUT;
|
|
set_y := '1';
|
|
if r.b.mantissa(UNIT_BIT + 1) = '1' then
|
|
-- rounding up of the mantissa caused overflow, meaning the
|
|
-- normalized B is 2.0. Since this is outside the range
|
|
-- of the LUT, just use 0.5 as the estimated inverse.
|
|
v.state := IDIV_USE0_5;
|
|
else
|
|
-- start the first multiply now
|
|
f_to_multiply.valid <= '1';
|
|
-- note we don't set v.first, thus the following IDIV_NR1
|
|
-- state doesn't start a multiply (we already did that)
|
|
v.state := IDIV_NR1;
|
|
end if;
|
|
when IDIV_NR1 =>
|
|
-- subsequent NR iterations do Y = P; P = 2 - B * P
|
|
msel_1 <= MUL1_B;
|
|
msel_add <= MULADD_CONST;
|
|
msel_inv <= '1';
|
|
msel_2 <= MUL2_P;
|
|
set_y := r.first;
|
|
pshift := '1';
|
|
f_to_multiply.valid <= r.first;
|
|
if multiply_to_f.valid = '1' then
|
|
v.first := '1';
|
|
v.count := r.count + 1;
|
|
v.state := IDIV_NR2;
|
|
end if;
|
|
when IDIV_NR2 =>
|
|
-- compute P = Y * P
|
|
msel_1 <= MUL1_Y;
|
|
msel_2 <= MUL2_P;
|
|
f_to_multiply.valid <= r.first;
|
|
pshift := '1';
|
|
v.opsel_a := AIN_A;
|
|
-- set shift to 64
|
|
rs_con2 <= RSCON2_64;
|
|
-- Get 0.5 into R in case the inverse estimate turns out to be
|
|
-- less than 0.5, in which case we want to use 0.5, to avoid
|
|
-- infinite loops in some cases.
|
|
opsel_r <= RES_MISC;
|
|
misc_sel <= "0001";
|
|
if multiply_to_f.valid = '1' then
|
|
v.first := '1';
|
|
if r.count = "11" then
|
|
v.state := IDIV_DODIV;
|
|
else
|
|
v.state := IDIV_NR1;
|
|
end if;
|
|
end if;
|
|
when IDIV_USE0_5 =>
|
|
-- Get 0.5 into R; it turns out the generated
|
|
-- QNaN mantissa is actually what we want
|
|
opsel_r <= RES_MISC;
|
|
misc_sel <= "0001";
|
|
v.opsel_a := AIN_A;
|
|
-- set shift to 64
|
|
rs_con2 <= RSCON2_64;
|
|
v.state := IDIV_DODIV;
|
|
when IDIV_DODIV =>
|
|
-- r.opsel_a = AIN_A
|
|
-- r.shift = 64
|
|
-- inverse estimate is in P or in R; copy it to Y
|
|
if r.b.mantissa(UNIT_BIT + 1) = '1' or
|
|
(r.p(UNIT_BIT) = '0' and r.p(UNIT_BIT - 1) = '0') then
|
|
msel_2 <= MUL2_R;
|
|
else
|
|
msel_2 <= MUL2_P;
|
|
end if;
|
|
set_y := '1';
|
|
-- shift_res is 0 because r.shift = 64;
|
|
-- put that into B, which now holds the quotient
|
|
set_b_mant := '1';
|
|
if r.divext = '0' then
|
|
-- set shift to -56
|
|
rs_con2 <= RSCON2_UNIT;
|
|
rs_neg2 <= '1';
|
|
v.first := '1';
|
|
v.state := IDIV_DIV;
|
|
elsif r.single_prec = '1' then
|
|
-- divwe[u][o], shift A left 32 bits
|
|
-- set shift to 32
|
|
rs_con2 <= RSCON2_32;
|
|
v.state := IDIV_SH32;
|
|
elsif r.div_close = '0' then
|
|
-- set shift to 64 - UNIT_BIT (== 8)
|
|
rs_con2 <= RSCON2_64_UNIT;
|
|
v.state := IDIV_EXTDIV;
|
|
else
|
|
-- handle top bit of quotient specially
|
|
-- for this we need the divisor left-justified in B
|
|
v.opsel_a := AIN_C;
|
|
v.state := IDIV_EXT_TBH;
|
|
end if;
|
|
when IDIV_SH32 =>
|
|
-- r.shift = 32, R contains the dividend
|
|
opsel_r <= RES_SHIFT;
|
|
-- set shift to -UNIT_BIT (== -56)
|
|
rs_con2 <= RSCON2_UNIT;
|
|
rs_neg2 <= '1';
|
|
v.first := '1';
|
|
v.state := IDIV_DIV;
|
|
when IDIV_DIV =>
|
|
-- Dividing A by C, r.shift = -56; A is in R
|
|
-- Put A into the bottom 64 bits of Ahi/A/Alo
|
|
set_a_mant := r.first;
|
|
set_a_lo := r.first;
|
|
-- compute R = R * Y (quotient estimate)
|
|
msel_1 <= MUL1_Y;
|
|
msel_2 <= MUL2_R;
|
|
f_to_multiply.valid <= r.first;
|
|
pshift := '1';
|
|
opsel_r <= RES_MULT;
|
|
-- set shift to - b.exp
|
|
rs_sel1 <= RSH1_B;
|
|
rs_neg1 <= '1';
|
|
if multiply_to_f.valid = '1' then
|
|
v.state := IDIV_DIV2;
|
|
end if;
|
|
when IDIV_DIV2 =>
|
|
-- r.shift = - b.exponent
|
|
-- shift the quotient estimate right by b.exponent bits
|
|
opsel_r <= RES_SHIFT;
|
|
v.first := '1';
|
|
v.state := IDIV_DIV3;
|
|
when IDIV_DIV3 =>
|
|
-- quotient (so far) is in R; multiply by C and subtract from A
|
|
msel_1 <= MUL1_R;
|
|
msel_2 <= MUL2_C;
|
|
msel_add <= MULADD_A;
|
|
msel_inv <= '1';
|
|
f_to_multiply.valid <= r.first;
|
|
-- store the current quotient estimate in B
|
|
set_b_mant := r.first;
|
|
opsel_r <= RES_MULT;
|
|
opsel_s <= S_MULT;
|
|
set_s := '1';
|
|
if multiply_to_f.valid = '1' then
|
|
v.state := IDIV_DIV4;
|
|
end if;
|
|
when IDIV_DIV4 =>
|
|
-- remainder is in R/S and P
|
|
msel_1 <= MUL1_Y;
|
|
msel_2 <= MUL2_P;
|
|
v.inc_quot := not pcmpc_lt and not r.divmod;
|
|
if r.divmod = '0' then
|
|
v.opsel_a := AIN_B;
|
|
end if;
|
|
-- set shift to UNIT_BIT (== 56)
|
|
rs_con2 <= RSCON2_UNIT;
|
|
if pcmpc_lt = '1' or pcmpc_eq = '1' then
|
|
if r.divmod = '0' then
|
|
v.state := IDIV_DIVADJ;
|
|
elsif pcmpc_eq = '1' then
|
|
v.state := IDIV_ZERO;
|
|
else
|
|
v.state := IDIV_MODADJ;
|
|
end if;
|
|
else
|
|
-- need to do another iteration, compute P * Y
|
|
f_to_multiply.valid <= '1';
|
|
v.state := IDIV_DIV5;
|
|
end if;
|
|
when IDIV_DIV5 =>
|
|
pshift := '1';
|
|
opsel_r <= RES_MULT;
|
|
-- set shift to - b.exp
|
|
rs_sel1 <= RSH1_B;
|
|
rs_neg1 <= '1';
|
|
if multiply_to_f.valid = '1' then
|
|
v.state := IDIV_DIV6;
|
|
end if;
|
|
when IDIV_DIV6 =>
|
|
-- r.shift = - b.exponent
|
|
-- shift the quotient estimate right by b.exponent bits
|
|
opsel_r <= RES_SHIFT;
|
|
v.opsel_a := AIN_B;
|
|
v.first := '1';
|
|
v.state := IDIV_DIV7;
|
|
when IDIV_DIV7 =>
|
|
-- r.opsel_a = AIN_B
|
|
-- add shifted quotient delta onto the total quotient
|
|
opsel_b <= BIN_R;
|
|
v.first := '1';
|
|
v.state := IDIV_DIV8;
|
|
when IDIV_DIV8 =>
|
|
-- quotient (so far) is in R; multiply by C and subtract from A
|
|
msel_1 <= MUL1_R;
|
|
msel_2 <= MUL2_C;
|
|
msel_add <= MULADD_A;
|
|
msel_inv <= '1';
|
|
f_to_multiply.valid <= r.first;
|
|
-- store the current quotient estimate in B
|
|
set_b_mant := r.first;
|
|
opsel_r <= RES_MULT;
|
|
opsel_s <= S_MULT;
|
|
set_s := '1';
|
|
if multiply_to_f.valid = '1' then
|
|
v.state := IDIV_DIV9;
|
|
end if;
|
|
when IDIV_DIV9 =>
|
|
-- remainder is in R/S and P
|
|
msel_1 <= MUL1_Y;
|
|
msel_2 <= MUL2_P;
|
|
v.inc_quot := not pcmpc_lt and not r.divmod;
|
|
if r.divmod = '0' then
|
|
v.opsel_a := AIN_B;
|
|
end if;
|
|
-- set shift to UNIT_BIT (== 56)
|
|
rs_con2 <= RSCON2_UNIT;
|
|
if r.divmod = '0' then
|
|
v.state := IDIV_DIVADJ;
|
|
elsif pcmpc_eq = '1' then
|
|
v.state := IDIV_ZERO;
|
|
else
|
|
v.state := IDIV_MODADJ;
|
|
end if;
|
|
when IDIV_EXT_TBH =>
|
|
-- r.opsel_a = AIN_C; get divisor into R and prepare to shift left
|
|
-- set shift to 63 - b.exp
|
|
rs_sel1 <= RSH1_B;
|
|
rs_neg1 <= '1';
|
|
rs_con2 <= RSCON2_63;
|
|
v.opsel_a := AIN_A;
|
|
v.state := IDIV_EXT_TBH2;
|
|
when IDIV_EXT_TBH2 =>
|
|
-- r.opsel_a = AIN_A; divisor is in R
|
|
-- r.shift = 63 - b.exponent; shift and put into B
|
|
set_b_mant := '1';
|
|
-- set shift to 64 - UNIT_BIT (== 8)
|
|
rs_con2 <= RSCON2_64_UNIT;
|
|
v.state := IDIV_EXT_TBH3;
|
|
when IDIV_EXT_TBH3 =>
|
|
-- Dividing (A << 64) by C
|
|
-- r.shift = 8
|
|
-- Put A in the top 64 bits of Ahi/A/Alo
|
|
set_a_hi := '1';
|
|
set_a_mant := '1';
|
|
-- set shift to 64 - b.exp
|
|
rs_sel1 <= RSH1_B;
|
|
rs_neg1 <= '1';
|
|
rs_con2 <= RSCON2_64;
|
|
v.state := IDIV_EXT_TBH4;
|
|
when IDIV_EXT_TBH4 =>
|
|
-- dividend (A) is in R
|
|
-- r.shift = 64 - B.exponent, so is at least 1
|
|
opsel_r <= RES_SHIFT;
|
|
-- top bit of A gets lost in the shift, so handle it specially
|
|
v.opsel_a := AIN_B;
|
|
-- set shift to 63
|
|
rs_con2 <= RSCON2_63;
|
|
v.state := IDIV_EXT_TBH5;
|
|
when IDIV_EXT_TBH5 =>
|
|
-- r.opsel_a = AIN_B, r.shift = 63
|
|
-- shifted dividend is in R, subtract left-justified divisor
|
|
opsel_b <= BIN_R;
|
|
opsel_ainv <= '1';
|
|
carry_in <= '1';
|
|
-- and put 1<<63 into B as the divisor (S is still 0)
|
|
shiftin0 := '1';
|
|
set_b_mant := '1';
|
|
v.first := '1';
|
|
v.state := IDIV_EXTDIV2;
|
|
when IDIV_EXTDIV =>
|
|
-- Dividing (A << 64) by C
|
|
-- r.shift = 8
|
|
-- Put A in the top 64 bits of Ahi/A/Alo
|
|
set_a_hi := '1';
|
|
set_a_mant := '1';
|
|
-- set shift to 64 - b.exp
|
|
rs_sel1 <= RSH1_B;
|
|
rs_neg1 <= '1';
|
|
rs_con2 <= RSCON2_64;
|
|
v.state := IDIV_EXTDIV1;
|
|
when IDIV_EXTDIV1 =>
|
|
-- dividend is in R
|
|
-- r.shift = 64 - B.exponent
|
|
opsel_r <= RES_SHIFT;
|
|
v.first := '1';
|
|
v.state := IDIV_EXTDIV2;
|
|
when IDIV_EXTDIV2 =>
|
|
-- shifted remainder is in R; compute R = R * Y (quotient estimate)
|
|
msel_1 <= MUL1_Y;
|
|
msel_2 <= MUL2_R;
|
|
f_to_multiply.valid <= r.first;
|
|
pshift := '1';
|
|
v.opsel_a := AIN_B;
|
|
opsel_r <= RES_MULT;
|
|
if multiply_to_f.valid = '1' then
|
|
v.first := '1';
|
|
v.state := IDIV_EXTDIV3;
|
|
end if;
|
|
when IDIV_EXTDIV3 =>
|
|
-- r.opsel_a = AIN_B
|
|
-- delta quotient is in R; add it to B
|
|
opsel_b <= BIN_R;
|
|
v.first := '1';
|
|
v.state := IDIV_EXTDIV4;
|
|
when IDIV_EXTDIV4 =>
|
|
-- quotient is in R; put it in B and compute remainder
|
|
set_b_mant := r.first;
|
|
msel_1 <= MUL1_R;
|
|
msel_2 <= MUL2_C;
|
|
msel_add <= MULADD_A;
|
|
msel_inv <= '1';
|
|
f_to_multiply.valid <= r.first;
|
|
opsel_r <= RES_MULT;
|
|
opsel_s <= S_MULT;
|
|
set_s := '1';
|
|
-- set shift to UNIT_BIT - b.exp
|
|
rs_sel1 <= RSH1_B;
|
|
rs_neg1 <= '1';
|
|
rs_con2 <= RSCON2_UNIT;
|
|
if multiply_to_f.valid = '1' then
|
|
v.state := IDIV_EXTDIV5;
|
|
end if;
|
|
when IDIV_EXTDIV5 =>
|
|
-- r.shift = r.b.exponent - 56
|
|
-- remainder is in R/S; shift it right r.b.exponent bits
|
|
opsel_r <= RES_SHIFT;
|
|
-- test LS 64b of remainder in P against divisor in C
|
|
v.inc_quot := not pcmpc_lt;
|
|
v.opsel_a := AIN_B;
|
|
v.state := IDIV_EXTDIV6;
|
|
when IDIV_EXTDIV6 =>
|
|
-- r.opsel_a = AIN_B
|
|
-- shifted remainder is in R, see if it is > 1
|
|
-- and compute R = R * Y if so
|
|
msel_1 <= MUL1_Y;
|
|
msel_2 <= MUL2_R;
|
|
pshift := '1';
|
|
if r_gt_1 = '1' then
|
|
f_to_multiply.valid <= '1';
|
|
v.state := IDIV_EXTDIV2;
|
|
else
|
|
v.state := IDIV_DIVADJ;
|
|
end if;
|
|
when IDIV_MODADJ =>
|
|
-- r.shift = 56
|
|
-- result is in R/S
|
|
opsel_r <= RES_SHIFT;
|
|
if pcmpc_lt = '0' then
|
|
v.opsel_a := AIN_C;
|
|
v.state := IDIV_MODSUB;
|
|
elsif r.result_sign = '0' then
|
|
v.state := IDIV_DONE;
|
|
else
|
|
v.state := IDIV_DIVADJ;
|
|
end if;
|
|
when IDIV_MODSUB =>
|
|
-- r.opsel_a = AIN_C
|
|
-- Subtract divisor from remainder
|
|
opsel_ainv <= '1';
|
|
carry_in <= '1';
|
|
opsel_b <= BIN_R;
|
|
if r.result_sign = '0' then
|
|
v.state := IDIV_DONE;
|
|
else
|
|
v.state := IDIV_DIVADJ;
|
|
end if;
|
|
when IDIV_DIVADJ =>
|
|
-- result (so far) is on the A input of the adder
|
|
-- set carry to increment quotient if needed
|
|
-- and also negate R if the answer is negative
|
|
opsel_ainv <= r.result_sign;
|
|
carry_in <= r.inc_quot xor r.result_sign;
|
|
rnd_b32 := '1';
|
|
if r.divmod = '0' then
|
|
opsel_b <= BIN_RND;
|
|
end if;
|
|
if r.is_signed = '0' then
|
|
v.state := IDIV_DONE;
|
|
else
|
|
v.state := IDIV_OVFCHK;
|
|
end if;
|
|
when IDIV_OVFCHK =>
|
|
if r.single_prec = '0' then
|
|
sign_bit := r.r(63);
|
|
else
|
|
sign_bit := r.r(31);
|
|
end if;
|
|
v.int_ovf := sign_bit xor r.result_sign;
|
|
if v.int_ovf = '1' then
|
|
v.state := IDIV_ZERO;
|
|
else
|
|
v.state := IDIV_DONE;
|
|
end if;
|
|
when IDIV_DONE =>
|
|
v.xerc_result := v.xerc;
|
|
if r.oe = '1' then
|
|
v.xerc_result.ov := '0';
|
|
v.xerc_result.ov32 := '0';
|
|
v.writing_xer := '1';
|
|
end if;
|
|
if r.m32b = '0' then
|
|
v.cr_result(3) := r.r(63);
|
|
v.cr_result(2 downto 1) := "00";
|
|
if r.r = 64x"0" then
|
|
v.cr_result(1) := '1';
|
|
else
|
|
v.cr_result(2) := not r.r(63);
|
|
end if;
|
|
else
|
|
v.cr_result(3) := r.r(31);
|
|
v.cr_result(2 downto 1) := "00";
|
|
if r.r(31 downto 0) = 32x"0" then
|
|
v.cr_result(1) := '1';
|
|
else
|
|
v.cr_result(2) := not r.r(31);
|
|
end if;
|
|
end if;
|
|
v.cr_result(0) := v.xerc.so;
|
|
int_result := '1';
|
|
v.writing_fpr := '1';
|
|
v.instr_done := '1';
|
|
when IDIV_ZERO =>
|
|
opsel_r <= RES_MISC;
|
|
misc_sel <= "0101";
|
|
v.xerc_result := v.xerc;
|
|
if r.oe = '1' then
|
|
v.xerc_result.ov := r.int_ovf;
|
|
v.xerc_result.ov32 := r.int_ovf;
|
|
v.xerc_result.so := r.xerc.so or r.int_ovf;
|
|
v.writing_xer := '1';
|
|
end if;
|
|
v.cr_result := "001" & v.xerc_result.so;
|
|
int_result := '1';
|
|
v.writing_fpr := '1';
|
|
v.instr_done := '1';
|
|
|
|
end case;
|
|
|
|
if zero_divide = '1' then
|
|
v.fpscr(FPSCR_ZX) := '1';
|
|
end if;
|
|
if qnan_result = '1' then
|
|
invalid := '1';
|
|
v.result_class := NAN;
|
|
v.result_sign := '0';
|
|
v.negate := '0';
|
|
misc_sel <= "0001";
|
|
opsel_r <= RES_MISC;
|
|
arith_done := '1';
|
|
end if;
|
|
if invalid = '1' then
|
|
v.invalid := '1';
|
|
end if;
|
|
if arith_done = '1' then
|
|
-- Enabled invalid exception doesn't write result or FPRF
|
|
-- Neither does enabled zero-divide exception
|
|
if (v.invalid and r.fpscr(FPSCR_VE)) = '0' and
|
|
(zero_divide and r.fpscr(FPSCR_ZE)) = '0' then
|
|
v.writing_fpr := '1';
|
|
v.update_fprf := '1';
|
|
end if;
|
|
v.instr_done := '1';
|
|
update_fx := '1';
|
|
end if;
|
|
|
|
-- Multiplier and divide/square root data path
|
|
case msel_1 is
|
|
when MUL1_A =>
|
|
f_to_multiply.data1 <= r.a.mantissa;
|
|
when MUL1_B =>
|
|
f_to_multiply.data1 <= r.b.mantissa;
|
|
when MUL1_Y =>
|
|
f_to_multiply.data1 <= r.y;
|
|
when others =>
|
|
f_to_multiply.data1 <= r.r;
|
|
end case;
|
|
case msel_2 is
|
|
when MUL2_C =>
|
|
f_to_multiply.data2 <= r.c.mantissa;
|
|
when MUL2_LUT =>
|
|
f_to_multiply.data2 <= std_ulogic_vector(shift_left(resize(unsigned(inverse_est), 64),
|
|
UNIT_BIT - 19));
|
|
when MUL2_P =>
|
|
f_to_multiply.data2 <= r.p;
|
|
when others =>
|
|
f_to_multiply.data2 <= r.r;
|
|
end case;
|
|
maddend := (others => '0');
|
|
case msel_add is
|
|
when MULADD_CONST =>
|
|
-- addend is 2.0 or 1.5 in 16.112 format
|
|
if r.is_sqrt = '0' then
|
|
maddend(2*UNIT_BIT + 1) := '1'; -- 2.0
|
|
else
|
|
maddend(2*UNIT_BIT downto 2*UNIT_BIT - 1) := "11"; -- 1.5
|
|
end if;
|
|
when MULADD_A =>
|
|
-- addend is A in 16.112 format
|
|
maddend(127 downto UNIT_BIT + 64) := r.a_hi;
|
|
maddend(UNIT_BIT + 63 downto UNIT_BIT) := r.a.mantissa;
|
|
maddend(UNIT_BIT - 1 downto 0) := r.a_lo;
|
|
when MULADD_RS =>
|
|
-- addend is concatenation of R and S in 16.112 format
|
|
maddend(UNIT_BIT + 63 downto UNIT_BIT) := r.r;
|
|
maddend(UNIT_BIT - 1 downto 0) := r.s;
|
|
when others =>
|
|
end case;
|
|
f_to_multiply.addend <= maddend;
|
|
f_to_multiply.subtract <= msel_inv;
|
|
if set_y = '1' then
|
|
v.y := f_to_multiply.data2;
|
|
end if;
|
|
if multiply_to_f.valid = '1' then
|
|
if pshift = '0' then
|
|
v.p := multiply_to_f.result(63 downto 0);
|
|
else
|
|
v.p := multiply_to_f.result(UNIT_BIT + 63 downto UNIT_BIT);
|
|
end if;
|
|
end if;
|
|
|
|
-- Data path.
|
|
-- This has A and B input multiplexers, an adder, a shifter,
|
|
-- count-leading-zeroes logic, and a result mux.
|
|
if r.longmask = '1' then
|
|
mshift := r.shift + to_signed(-29, EXP_BITS);
|
|
else
|
|
mshift := r.shift;
|
|
end if;
|
|
if is_X(mshift) then
|
|
mask := (others => 'X');
|
|
elsif mshift < to_signed(-64, EXP_BITS) then
|
|
mask := (others => '1');
|
|
elsif mshift >= to_signed(0, EXP_BITS) then
|
|
mask := (others => '0');
|
|
else
|
|
mask := right_mask(unsigned(mshift(5 downto 0)));
|
|
end if;
|
|
case r.opsel_a is
|
|
when AIN_R =>
|
|
in_a0 := r.r;
|
|
when AIN_A =>
|
|
in_a0 := r.a.mantissa;
|
|
when AIN_B =>
|
|
in_a0 := r.b.mantissa;
|
|
when others =>
|
|
in_a0 := r.c.mantissa;
|
|
end case;
|
|
if (or (mask and in_a0)) = '1' and set_x = '1' then
|
|
v.x := '1';
|
|
end if;
|
|
if opsel_ainv = '1' then
|
|
in_a0 := not in_a0;
|
|
end if;
|
|
in_a <= in_a0;
|
|
case opsel_b is
|
|
when BIN_ZERO =>
|
|
in_b0 := (others => '0');
|
|
when BIN_R =>
|
|
in_b0 := r.r;
|
|
when BIN_RND =>
|
|
if rnd_b32 = '1' then
|
|
round_inc := (32 => r.result_sign and r.single_prec, others => '0');
|
|
elsif rbit_inc = '0' then
|
|
round_inc := (SP_LSB => r.single_prec, DP_LSB => not r.single_prec, others => '0');
|
|
else
|
|
round_inc := (DP_RBIT => '1', others => '0');
|
|
end if;
|
|
in_b0 := round_inc;
|
|
when others =>
|
|
-- BIN_PS8, 8 LSBs of P sign-extended to 64
|
|
in_b0 := std_ulogic_vector(resize(signed(r.p(7 downto 0)), 64));
|
|
end case;
|
|
if opsel_binv = '1' then
|
|
in_b0 := not in_b0;
|
|
end if;
|
|
in_b <= in_b0;
|
|
if is_X(r.shift) then
|
|
shift_res := (others => 'X');
|
|
elsif r.shift >= to_signed(-64, EXP_BITS) and r.shift <= to_signed(63, EXP_BITS) then
|
|
shift_res := shifter_64(r.r(63 downto 1) & (shiftin0 or r.r(0)) &
|
|
(shiftin or r.s(55)) & r.s(54 downto 0),
|
|
std_ulogic_vector(r.shift(6 downto 0)));
|
|
else
|
|
shift_res := (others => '0');
|
|
end if;
|
|
sum := std_ulogic_vector(unsigned(in_a) + unsigned(in_b) + carry_in);
|
|
if opsel_mask = '1' then
|
|
sum(DP_LSB - 1 downto 0) := "0000";
|
|
if r.single_prec = '1' then
|
|
sum(SP_LSB - 1 downto DP_LSB) := (others => '0');
|
|
end if;
|
|
end if;
|
|
case opsel_r is
|
|
when RES_SUM =>
|
|
result <= sum;
|
|
when RES_SHIFT =>
|
|
result <= shift_res;
|
|
when RES_MULT =>
|
|
result <= multiply_to_f.result(UNIT_BIT + 63 downto UNIT_BIT);
|
|
if mult_mask = '1' then
|
|
-- trim to 54 fraction bits if mult_mask = 1, for quotient when dividing
|
|
result(UNIT_BIT - 55 downto 0) <= (others => '0');
|
|
end if;
|
|
when others =>
|
|
misc := (others => '0');
|
|
case misc_sel is
|
|
when "0000" =>
|
|
misc := x"00000000" & (r.fpscr and fpscr_mask);
|
|
when "0001" =>
|
|
-- generated QNaN mantissa
|
|
misc(QNAN_BIT) := '1';
|
|
when "0010" =>
|
|
-- mantissa of max representable DP number
|
|
misc(UNIT_BIT downto DP_LSB) := (others => '1');
|
|
when "0011" =>
|
|
-- mantissa of max representable SP number
|
|
misc(UNIT_BIT downto SP_LSB) := (others => '1');
|
|
when "0100" =>
|
|
-- fmrgow result
|
|
misc := r.a.mantissa(31 downto 0) & r.b.mantissa(31 downto 0);
|
|
when "0110" =>
|
|
-- fmrgew result
|
|
misc := r.a.mantissa(63 downto 32) & r.b.mantissa(63 downto 32);
|
|
when "0111" =>
|
|
misc := std_ulogic_vector(shift_left(resize(unsigned(inverse_est), 64),
|
|
UNIT_BIT - 19));
|
|
when "1000" =>
|
|
-- max positive result for fctiw[z]
|
|
misc := x"000000007fffffff";
|
|
when "1001" =>
|
|
-- max negative result for fctiw[z]
|
|
misc := x"ffffffff80000000";
|
|
when "1010" =>
|
|
-- max positive result for fctiwu[z]
|
|
misc := x"00000000ffffffff";
|
|
when "1011" =>
|
|
-- max negative result for fctiwu[z]
|
|
misc := x"0000000000000000";
|
|
when "1100" =>
|
|
-- max positive result for fctid[z]
|
|
misc := x"7fffffffffffffff";
|
|
when "1101" =>
|
|
-- max negative result for fctid[z]
|
|
misc := x"8000000000000000";
|
|
when "1110" =>
|
|
-- max positive result for fctidu[z]
|
|
misc := x"ffffffffffffffff";
|
|
when "1111" =>
|
|
-- max negative result for fctidu[z]
|
|
misc := x"0000000000000000";
|
|
when others =>
|
|
end case;
|
|
result <= misc;
|
|
end case;
|
|
v.r := result;
|
|
if set_s = '1' then
|
|
case opsel_s is
|
|
when S_NEG =>
|
|
v.s := std_ulogic_vector(unsigned(not r.s) + (not r.x));
|
|
when S_MULT =>
|
|
v.s := multiply_to_f.result(55 downto 0);
|
|
when S_SHIFT =>
|
|
v.s := shift_res(63 downto 8);
|
|
if shift_res(7 downto 0) /= x"00" then
|
|
v.x := '1';
|
|
end if;
|
|
when others =>
|
|
v.s := (others => '0');
|
|
end case;
|
|
end if;
|
|
|
|
if set_a = '1' or set_a_exp = '1' then
|
|
v.a.exponent := new_exp;
|
|
end if;
|
|
if set_a = '1' or set_a_mant = '1' then
|
|
v.a.mantissa := shift_res;
|
|
end if;
|
|
if e_in.valid = '1' then
|
|
v.a_hi := (others => '0');
|
|
v.a_lo := (others => '0');
|
|
else
|
|
if set_a_hi = '1' then
|
|
v.a_hi := r.r(63 downto 56);
|
|
end if;
|
|
if set_a_lo = '1' then
|
|
v.a_lo := r.r(55 downto 0);
|
|
end if;
|
|
end if;
|
|
if set_b = '1' then
|
|
v.b.exponent := new_exp;
|
|
end if;
|
|
if set_b = '1' or set_b_mant = '1' then
|
|
v.b.mantissa := shift_res;
|
|
end if;
|
|
if set_c = '1' then
|
|
v.c.exponent := new_exp;
|
|
v.c.mantissa := shift_res;
|
|
end if;
|
|
|
|
-- exponent data path
|
|
case re_sel1 is
|
|
when REXP1_R =>
|
|
rexp_in1 := r.result_exp;
|
|
when REXP1_A =>
|
|
rexp_in1 := r.a.exponent;
|
|
when REXP1_BHALF =>
|
|
rexp_in1 := r.b.exponent(EXP_BITS-1) & r.b.exponent(EXP_BITS-1 downto 1);
|
|
when others =>
|
|
rexp_in1 := to_signed(0, EXP_BITS);
|
|
end case;
|
|
if re_neg1 = '1' then
|
|
rexp_in1 := not rexp_in1;
|
|
end if;
|
|
case re_sel2 is
|
|
when REXP2_NE =>
|
|
rexp_in2 := new_exp;
|
|
when REXP2_C =>
|
|
rexp_in2 := r.c.exponent;
|
|
when REXP2_B =>
|
|
rexp_in2 := r.b.exponent;
|
|
when others =>
|
|
case re_con2 is
|
|
when RECON2_UNIT =>
|
|
rexp_in2 := to_signed(UNIT_BIT, EXP_BITS);
|
|
when RECON2_MAX =>
|
|
rexp_in2 := max_exp;
|
|
when RECON2_BIAS =>
|
|
rexp_in2 := bias_exp;
|
|
when others =>
|
|
rexp_in2 := to_signed(0, EXP_BITS);
|
|
end case;
|
|
end case;
|
|
if re_neg2 = '1' then
|
|
rexp_in2 := not rexp_in2;
|
|
end if;
|
|
rexp_cin := re_neg1 or re_neg2;
|
|
rexp_sum := rexp_in1 + rexp_in2 + rexp_cin;
|
|
if re_set_result = '1' then
|
|
v.result_exp := rexp_sum;
|
|
end if;
|
|
case rs_sel1 is
|
|
when RSH1_B =>
|
|
rsh_in1 := r.b.exponent;
|
|
when RSH1_NE =>
|
|
rsh_in1 := new_exp;
|
|
when RSH1_S =>
|
|
rsh_in1 := r.shift;
|
|
when others =>
|
|
rsh_in1 := to_signed(0, EXP_BITS);
|
|
end case;
|
|
if rs_neg1 = '1' then
|
|
rsh_in1 := not rsh_in1;
|
|
end if;
|
|
case rs_sel2 is
|
|
when RSH2_A =>
|
|
rsh_in2 := r.a.exponent;
|
|
when others =>
|
|
case rs_con2 is
|
|
when RSCON2_1 =>
|
|
rsh_in2 := to_signed(1, EXP_BITS);
|
|
when RSCON2_UNIT_52 =>
|
|
rsh_in2 := to_signed(UNIT_BIT - 52, EXP_BITS);
|
|
when RSCON2_64_UNIT =>
|
|
rsh_in2 := to_signed(64 - UNIT_BIT, EXP_BITS);
|
|
when RSCON2_32 =>
|
|
rsh_in2 := to_signed(32, EXP_BITS);
|
|
when RSCON2_52 =>
|
|
rsh_in2 := to_signed(52, EXP_BITS);
|
|
when RSCON2_UNIT =>
|
|
rsh_in2 := to_signed(UNIT_BIT, EXP_BITS);
|
|
when RSCON2_63 =>
|
|
rsh_in2 := to_signed(63, EXP_BITS);
|
|
when RSCON2_64 =>
|
|
rsh_in2 := to_signed(64, EXP_BITS);
|
|
when RSCON2_MINEXP =>
|
|
rsh_in2 := min_exp;
|
|
when others =>
|
|
rsh_in2 := to_signed(0, EXP_BITS);
|
|
end case;
|
|
end case;
|
|
if rs_neg2 = '1' then
|
|
rsh_in2 := not rsh_in2;
|
|
end if;
|
|
if rs_norm = '1' then
|
|
clz := count_left_zeroes(r.r);
|
|
if renorm_sqrt = '1' then
|
|
-- make denormalized value end up with even exponent
|
|
clz(0) := '1';
|
|
end if;
|
|
-- do this as a separate dedicated 7-bit adder for timing reasons
|
|
v.shift := resize(signed('0' & clz) - (63 - UNIT_BIT), EXP_BITS);
|
|
else
|
|
v.shift := rsh_in1 + rsh_in2 + (rs_neg1 or rs_neg2);
|
|
end if;
|
|
|
|
if r.update_fprf = '1' then
|
|
v.fpscr(FPSCR_C downto FPSCR_FU) := result_flags(r.result_sign, r.result_class,
|
|
r.r(UNIT_BIT) and not r.denorm);
|
|
end if;
|
|
|
|
v.fpscr(FPSCR_VX) := (or (v.fpscr(FPSCR_VXSNAN downto FPSCR_VXVC))) or
|
|
(or (v.fpscr(FPSCR_VXSOFT downto FPSCR_VXCVI)));
|
|
v.fpscr(FPSCR_FEX) := or (v.fpscr(FPSCR_VX downto FPSCR_XX) and
|
|
v.fpscr(FPSCR_VE downto FPSCR_XE));
|
|
if update_fx = '1' and
|
|
(v.fpscr(FPSCR_VX downto FPSCR_XX) and not r.old_exc) /= "00000" then
|
|
v.fpscr(FPSCR_FX) := '1';
|
|
end if;
|
|
|
|
if v.instr_done = '1' then
|
|
if r.state /= IDLE then
|
|
v.state := IDLE;
|
|
v.busy := '0';
|
|
v.f2stall := '0';
|
|
if r.fp_rc = '1' then
|
|
v.cr_result := v.fpscr(FPSCR_FX downto FPSCR_OX);
|
|
end if;
|
|
v.sp_result := r.single_prec;
|
|
v.int_result := int_result;
|
|
v.illegal := illegal;
|
|
v.nsnan_result := v.quieten_nan;
|
|
v.res_negate := v.negate;
|
|
v.res_subtract := v.is_subtract;
|
|
v.res_rmode := r.round_mode;
|
|
if r.integer_op = '1' then
|
|
v.cr_mask := num_to_fxm(0);
|
|
elsif r.is_cmp = '0' then
|
|
v.cr_mask := num_to_fxm(1);
|
|
elsif is_X(insn_bf(r.insn)) then
|
|
v.cr_mask := (others => 'X');
|
|
else
|
|
v.cr_mask := num_to_fxm(to_integer(unsigned(insn_bf(r.insn))));
|
|
end if;
|
|
v.writing_cr := r.is_cmp or r.rc;
|
|
v.write_reg := r.dest_fpr;
|
|
v.complete_tag := r.instr_tag;
|
|
end if;
|
|
if e_in.stall = '0' then
|
|
v.complete := not v.illegal;
|
|
v.do_intr := (v.fpscr(FPSCR_FEX) and r.fe_mode) or v.illegal;
|
|
end if;
|
|
-- N.B. We rely on execute1 to prevent any new instruction
|
|
-- coming in while e_in.stall = 1, without us needing to
|
|
-- have busy asserted.
|
|
else
|
|
if r.state /= IDLE and e_in.stall = '0' then
|
|
v.f2stall := '1';
|
|
end if;
|
|
end if;
|
|
|
|
-- This mustn't depend on any fields of r that are modified in IDLE state.
|
|
if r.int_result = '1' then
|
|
fp_result <= r.r;
|
|
else
|
|
fp_result <= pack_dp(r.result_sign, r.result_class, r.result_exp, r.r,
|
|
r.sp_result, r.nsnan_result,
|
|
r.res_negate, r.res_subtract, r.res_rmode);
|
|
end if;
|
|
|
|
rin <= v;
|
|
end process;
|
|
|
|
end architecture behaviour;
|