[libre-riscv-dev] IEEE754 FPU turning into ALU with Reservation Stations

Luke Kenneth Casson Leighton lkcl at lkcl.net
Fri Mar 15 14:22:28 GMT 2019

On Fri, Mar 15, 2019 at 2:05 PM Aleksandar Kostovic
<alexandar.kostovic at gmail.com> wrote:
> ok i am starting to get it

 cool.  i have to go to hong kong tomorrow, will be back sunday night.
  see if you can create a special cases class paid
(FPMulSpecialCasesMod and FPMulSpecialCases) - these you _will_ have
to copy from nmigen_add_experiment.py (and then adapt).  watch out for
a couple of things:

 (1) out_do_z is set inside the SpecialCasesMod class, and whether it
is set or not is used to decide which new FSM state to move to in the
FPMul(Add)SpecialCases class

 (2) if you copy the code exactly, you'll need to add back in a
denormalise stage: in add, i separated out denormalisation.

if you want to see how to use the FPXXXSpecialCases class, see
get_longer_fragment, do *not* copy the get_compact_fragment code yet.


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