[libre-riscv-dev] priority encoder replacement

Luke Kenneth Casson Leighton lkcl at lkcl.net
Tue May 19 19:46:58 BST 2020


On Tuesday, May 19, 2020, Jacob Lifshay <programmerjake at gmail.com> wrote:


>
>
> If clz is strictly better, replace PriorityEncoder with clz, or just change
> clz to match PriorityEncoder's interface and rename it PriorityEncoder,
> deleting the old one.


it does have some subtle differences, PE sets a flag when the input is
entirely zero.

i do not believe there is an offbyone.  PE will set its output to 0 if bit
0 is 1.  output is 1 if input is 0bxxx10 which is pretty much the
definition of CLZ.

l.



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