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microwatt/multiply.vhdl

85 lines
2.6 KiB
VHDL

library ieee;
use ieee.std_logic_1164.all;
use ieee.numeric_std.all;
library work;
use work.common.all;
entity multiply is
generic (
PIPELINE_DEPTH : natural := 4
);
port (
clk : in std_logic;
m_in : in Execute1ToMultiplyType;
m_out : out MultiplyToExecute1Type
);
end entity multiply;
architecture behaviour of multiply is
signal m: Execute1ToMultiplyType := Execute1ToMultiplyInit;
type multiply_pipeline_stage is record
valid : std_ulogic;
data : unsigned(127 downto 0);
is_32bit : std_ulogic;
neg_res : std_ulogic;
end record;
constant MultiplyPipelineStageInit : multiply_pipeline_stage := (valid => '0',
is_32bit => '0', neg_res => '0',
data => (others => '0'));
type multiply_pipeline_type is array(0 to PIPELINE_DEPTH-1) of multiply_pipeline_stage;
constant MultiplyPipelineInit : multiply_pipeline_type := (others => MultiplyPipelineStageInit);
type reg_type is record
multiply_pipeline : multiply_pipeline_type;
end record;
signal r, rin : reg_type := (multiply_pipeline => MultiplyPipelineInit);
begin
multiply_0: process(clk)
begin
if rising_edge(clk) then
m <= m_in;
r <= rin;
end if;
end process;
multiply_1: process(all)
variable v : reg_type;
variable d : std_ulogic_vector(127 downto 0);
variable d2 : std_ulogic_vector(63 downto 0);
variable ov : std_ulogic;
begin
v.multiply_pipeline(0).valid := m.valid;
v.multiply_pipeline(0).data := unsigned(m.data1) * unsigned(m.data2);
v.multiply_pipeline(0).is_32bit := m.is_32bit;
v.multiply_pipeline(0).neg_res := m.neg_result;
loop_0: for i in 1 to PIPELINE_DEPTH-1 loop
v.multiply_pipeline(i) := r.multiply_pipeline(i-1);
end loop;
if v.multiply_pipeline(PIPELINE_DEPTH-1).neg_res = '0' then
d := std_ulogic_vector(v.multiply_pipeline(PIPELINE_DEPTH-1).data);
else
d := std_ulogic_vector(- signed(v.multiply_pipeline(PIPELINE_DEPTH-1).data));
end if;
ov := '0';
if v.multiply_pipeline(PIPELINE_DEPTH-1).is_32bit = '1' then
ov := (or d(63 downto 31)) and not (and d(63 downto 31));
else
ov := (or d(127 downto 63)) and not (and d(127 downto 63));
end if;
m_out.result <= d;
m_out.overflow <= ov;
m_out.valid <= v.multiply_pipeline(PIPELINE_DEPTH-1).valid;
rin <= v;
end process;
end architecture behaviour;