From 14c1fd4d27fa3bf9b4b68ffe3b088160ba6cbee4 Mon Sep 17 00:00:00 2001 From: Marco Costalba Date: Sun, 11 Jan 2009 17:05:29 +0100 Subject: [PATCH] Micro optimize count_1s_max_15() for 32 bit system Signed-off-by: Marco Costalba --- src/bitboard.h | 9 ++++----- 1 file changed, 4 insertions(+), 5 deletions(-) diff --git a/src/bitboard.h b/src/bitboard.h index 847132c4..11406648 100644 --- a/src/bitboard.h +++ b/src/bitboard.h @@ -397,11 +397,10 @@ inline int count_1s(Bitboard b) { unsigned w = unsigned(b >> 32), v = unsigned(b); v = v - ((v >> 1) & 0x55555555); w = w - ((w >> 1) & 0x55555555); + v += w; v = (v & 0x33333333) + ((v >> 2) & 0x33333333); - w = (w & 0x33333333) + ((w >> 2) & 0x33333333); v = (v + (v >> 4)) & 0x0F0F0F0F; - w = (w + (w >> 4)) & 0x0F0F0F0F; - v = ((v+w) * 0x01010101) >> 24; // mul is fast on amd procs + v = (v * 0x01010101) >> 24; // mul is fast on amd procs return int(v); } @@ -409,9 +408,9 @@ inline int count_1s_max_15(Bitboard b) { unsigned w = unsigned(b >> 32), v = unsigned(b); v = v - ((v >> 1) & 0x55555555); w = w - ((w >> 1) & 0x55555555); + v += w; v = (v & 0x33333333) + ((v >> 2) & 0x33333333); - w = (w & 0x33333333) + ((w >> 2) & 0x33333333); - v = ((v+w) * 0x11111111) >> 28; + v = (v * 0x11111111) >> 28; return int(v); } -- 2.39.2