From: Luke Kenneth Casson Leighton <lkcl@lkcl.net>
Date: Thu, 22 Jul 2021 14:24:00 +0000 (+0100)
Subject: simplification of halfrev2 algorithm (really neat)
X-Git-Tag: xlen-bcd~235
X-Git-Url: https://git.libre-soc.org/?a=commitdiff_plain;h=8a0759602983254d13f91196ec977f3dbccfaf05;p=openpower-isa.git

simplification of halfrev2 algorithm (really neat)
---

diff --git a/src/openpower/decoder/isa/fastdctlee.py b/src/openpower/decoder/isa/fastdctlee.py
index f9f481b7..f2641461 100644
--- a/src/openpower/decoder/isa/fastdctlee.py
+++ b/src/openpower/decoder/isa/fastdctlee.py
@@ -102,8 +102,7 @@ def halfrev2(vec, pre_rev=True):
             ri = i
             bl = i.bit_length()
             for ji in range(1, bl):
-                if (1<<ji) & i:
-                    ri ^= ((1<<ji)-1)
+                ri ^= (i >> ji)
             res.append(vec[ri])
     return res