From 3e6e57231ecb1c23e43e02109efa3bcaf7ebe7c3 Mon Sep 17 00:00:00 2001 From: Marco Costalba Date: Sun, 11 Jan 2009 17:15:18 +0100 Subject: [PATCH] Rewrite count_1s() to be similar to 64bit counterpart No functional change. Signed-off-by: Marco Costalba --- src/bitboard.h | 22 +++++++++++----------- 1 file changed, 11 insertions(+), 11 deletions(-) diff --git a/src/bitboard.h b/src/bitboard.h index 11406648..2280f66c 100644 --- a/src/bitboard.h +++ b/src/bitboard.h @@ -395,23 +395,23 @@ inline int count_1s_max_15(Bitboard b) { 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 -= (v >> 1) & 0x55555555; + w -= (w >> 1) & 0x55555555; v += w; - v = (v & 0x33333333) + ((v >> 2) & 0x33333333); - v = (v + (v >> 4)) & 0x0F0F0F0F; - v = (v * 0x01010101) >> 24; // mul is fast on amd procs - return int(v); + v = ((v >> 2) & 0x33333333) + (v & 0x33333333); + v = ((v >> 4) + v) & 0x0F0F0F0F; + v *= 0x01010101; // mul is fast on amd procs + return int(v >> 24); } 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 -= (v >> 1) & 0x55555555; + w -= (w >> 1) & 0x55555555; v += w; - v = (v & 0x33333333) + ((v >> 2) & 0x33333333); - v = (v * 0x11111111) >> 28; - return int(v); + v = ((v >> 2) & 0x33333333) + (v & 0x33333333); + v *= 0x11111111; + return int(v >> 28); } #elif defined(BITCOUNT_SWAR_64) -- 2.39.2