From be46799e6a47902ba1c695489327238452b01aff Mon Sep 17 00:00:00 2001 From: Luke Kenneth Casson Leighton Date: Fri, 29 May 2020 22:33:46 +0100 Subject: [PATCH] comments on popcount --- src/soc/fu/logical/popcount.py | 10 +++++----- 1 file changed, 5 insertions(+), 5 deletions(-) diff --git a/src/soc/fu/logical/popcount.py b/src/soc/fu/logical/popcount.py index 6f47300b..d655b551 100644 --- a/src/soc/fu/logical/popcount.py +++ b/src/soc/fu/logical/popcount.py @@ -27,7 +27,7 @@ class Popcount(Elaboratable): pc = [a] # QTY32 2-bit (to take 2x 1-bit sums) etc. work = [(32, 2), (16, 3), (8, 4), (4, 5), (2, 6), (1, 7)] - for l, bw in work: + for l, bw in work: # l=number of add-reductions, bw=bitwidth pc.append(array_of(l, bw)) pc8 = pc[3] # array of 8 8-bit counts (popcntb) pc32 = pc[5] # array of 2 32-bit counts (popcntw) @@ -39,17 +39,17 @@ class Popcount(Elaboratable): src, dst = pc[idx], pc[idx+1] comb += dst[i].eq(Cat(src[stt], Const(0, 1)) + Cat(src[end], Const(0, 1))) - # decode operation length + # decode operation length (1-hot) with m.If(data_len == 1): - # popcntb - pack 8x 4-bit answers into output + # popcntb - pack 8x 4-bit answers into 8x 8-bit output fields for i in range(8): comb += o[i*8:(i+1)*8].eq(pc8[i]) with m.Elif(data_len == 4): - # popcntw - pack 2x 5-bit answers into output + # popcntw - pack 2x 5-bit answers into 2x 32-bit output fields for i in range(2): comb += o[i*32:(i+1)*32].eq(pc32[i]) with m.Else(): - # popcntd - put 1x 6-bit answer into output + # popcntd - put 1x 6-bit answer into 64-bit output comb += o.eq(popcnt[0]) return m -- 2.30.2