From: Luke Kenneth Casson Leighton <lkcl@lkcl.net>
Date: Tue, 9 Jan 2024 14:10:32 +0000 (+0000)
Subject: bug 1244: update pospopcnt.s assembler comments
X-Git-Url: https://git.libre-soc.org/?a=commitdiff_plain;h=b1331f37e6b41ac133f4286486a4af27b3f7fc1a;hp=ccfc957b55d0163099cb66301bcfe30ca1b8e6b4;p=libreriscv.git

bug 1244: update pospopcnt.s assembler comments
---

diff --git a/conferences/fosdem2024/fosdem2024_ddffirst/pospopcount.s b/conferences/fosdem2024/fosdem2024_ddffirst/pospopcount.s
index 2b905f135..3bbdddf10 100644
--- a/conferences/fosdem2024/fosdem2024_ddffirst/pospopcount.s
+++ b/conferences/fosdem2024/fosdem2024_ddffirst/pospopcount.s
@@ -1,13 +1,12 @@
 mtspr 9, 3              # move r3 to CTR
 setvl 3,0,8,0,1,1       # MVL=8, VL=r3=MIN(MVL,CTR)
-# load VL bytes (update r4 addr) but width=8 (dw=8)
-addi 6, 0, 0            # set 64-bits of r6=0
-sv.lbzu/pi/dw=8 *6, 1(4) 
-# gather performs transpose (gets us to positional)
-gbbd 8,6
-# now bits are turned around, popcount and sum them
+# load VL bytes (update r4 addr) at width=8 (dw=8)
+addi 6, 0, 0            # set all 64-bits of r6=0
+sv.lbzu/pi/dw=8 *6, 1(4)
+gbbd 8,6 # gbbd performs the transpose
+# now bits are turned around, popcnt and sum them
 setvl 0,0,8,0,1,1       # set MVL=VL=8
 sv.popcntd/sw=8 *24,*8  # do (transposed) popcnt
 sv.add *16,*16,*24      # accumulate in results
-# branch back if CTR non-zero. works even when VL=8
-sv.bc/all 16, *0, -0x28 # reduce CTR by VL
+# branch back if CTR non-zero works even when VL=8
+sv.bc/all 16, *0, -0x28 # reduces CTR by VL