diff options
Diffstat (limited to 'src/common')
-rw-r--r-- | src/common/bit_util.h | 45 |
1 files changed, 33 insertions, 12 deletions
diff --git a/src/common/bit_util.h b/src/common/bit_util.h index 14e53c273..70e728a5e 100644 --- a/src/common/bit_util.h +++ b/src/common/bit_util.h @@ -59,22 +59,43 @@ inline u64 CountLeadingZeroes64(u64 value) { } #endif + +#ifdef _MSC_VER inline u32 CountTrailingZeroes32(u32 value) { - u32 count = 0; - while (((value >> count) & 0xf) == 0 && count < 32) - count += 4; - while (((value >> count) & 1) == 0 && count < 32) - count++; - return count; + unsigned long trailing_zero = 0; + + if (_BitScanForward(&trailing_zero, value) != 0) { + return trailing_zero; + } + + return 32; } inline u64 CountTrailingZeroes64(u64 value) { - u64 count = 0; - while (((value >> count) & 0xf) == 0 && count < 64) - count += 4; - while (((value >> count) & 1) == 0 && count < 64) - count++; - return count; + unsigned long trailing_zero = 0; + + if (_BitScanForward64(&trailing_zero, value) != 0) { + return trailing_zero; + } + + return 64; } +#else +inline u32 CountTrailingZeroes32(u32 value) { + if (value == 0) { + return 32; + } + + return __builtin_ctz(value); +} + +inline u64 CountTrailingZeroes64(u64 value) { + if (value == 0) { + return 64; + } + + return __builtin_ctzll(value); +} +#endif } // namespace Common |