From 0ce5ec8ece78f7936dc7bf0ad58fa1ed01783e25 Mon Sep 17 00:00:00 2001 From: =?utf8?q?Mathias=20Fr=C3=B6hlich?= Date: Sat, 6 Aug 2016 07:26:51 +0200 Subject: [PATCH] util: Use win32 intrinsics for util_last_bit if present. MIME-Version: 1.0 Content-Type: text/plain; charset=utf8 Content-Transfer-Encoding: 8bit v2: Split into two patches. v3: Fix off by one problem. Signed-off-by: Mathias Fröhlich Reviewed-by: Brian Paul Tested-by: Brian Paul --- src/util/bitscan.h | 12 ++++++++++++ 1 file changed, 12 insertions(+) diff --git a/src/util/bitscan.h b/src/util/bitscan.h index 0743fe7d321..8afef81a990 100644 --- a/src/util/bitscan.h +++ b/src/util/bitscan.h @@ -157,6 +157,12 @@ util_last_bit(unsigned u) { #if defined(HAVE___BUILTIN_CLZ) return u == 0 ? 0 : 32 - __builtin_clz(u); +#elif defined(_MSC_VER) && (_M_IX86 || _M_ARM || _M_AMD64 || _M_IA64) + unsigned long index; + if (_BitScanReverse(&index, u)) + return index + 1; + else + return 0; #else unsigned r = 0; while (u) { @@ -177,6 +183,12 @@ util_last_bit64(uint64_t u) { #if defined(HAVE___BUILTIN_CLZLL) return u == 0 ? 0 : 64 - __builtin_clzll(u); +#elif defined(_MSC_VER) && (_M_AMD64 || _M_ARM || _M_IA64) + unsigned long index; + if (_BitScanReverse64(&index, u)) + return index + 1; + else + return 0; #else unsigned r = 0; while (u) { -- 2.30.2