Commit Graph

2 Commits (ae55f5efbd2a57e591a2de31d068a9a974fbe770)

Author SHA1 Message Date
Paul Mackerras e08ca4ab8e countzero: Add a register to help make timing
This adds a register in the middle of the countzero computation,
so that we now have two cycles to count leading or trailing zeroes
instead of just one.  Execute1 now outputs a one-cycle stall signal
when it encounters a cntlz* or cnttz* instruction.  With this,
the countzero path no longer fails timing on the Artix-7 at 100MHz.

Signed-off-by: Paul Mackerras <>
4 years ago
Paul Mackerras 4396eddc31 countzero: Add a testbench
Signed-off-by: Paul Mackerras <>
5 years ago