From 5a8c7606df9c7485708c3961f01ddd3fd356260b Mon Sep 17 00:00:00 2001 From: nxtn-staged <79820545+nxtn-staged@users.noreply.github.com> Date: Tue, 27 Dec 2022 11:23:19 +0800 Subject: [PATCH] Use _BitScanReverse on Win32 --- include/fast_double_parser.h | 18 ++++++------------ 1 file changed, 6 insertions(+), 12 deletions(-) diff --git a/include/fast_double_parser.h b/include/fast_double_parser.h index d6d8e78..2198097 100644 --- a/include/fast_double_parser.h +++ b/include/fast_double_parser.h @@ -193,24 +193,18 @@ really_inline value128 full_multiplication(uint64_t value1, uint64_t value2) { /* result might be undefined when input_num is zero */ inline int leading_zeroes(uint64_t input_num) { #ifdef _MSC_VER -#if defined(_M_X64) || defined(_M_ARM64) || defined (_M_IA64) unsigned long leading_zero = 0; // Search the mask data from most significant bit (MSB) // to least significant bit (LSB) for a set bit (1). +#ifdef _WIN64 if (_BitScanReverse64(&leading_zero, input_num)) return (int)(63 - leading_zero); - else - return 64; #else - int last_bit = 0; - if(input_num & uint64_t(0xffffffff00000000)) input_num >>= 32, last_bit |= 32; - if(input_num & uint64_t( 0xffff0000)) input_num >>= 16, last_bit |= 16; - if(input_num & uint64_t( 0xff00)) input_num >>= 8, last_bit |= 8; - if(input_num & uint64_t( 0xf0)) input_num >>= 4, last_bit |= 4; - if(input_num & uint64_t( 0xc)) input_num >>= 2, last_bit |= 2; - if(input_num & uint64_t( 0x2)) input_num >>= 1, last_bit |= 1; - return 63 - last_bit; -#endif // defined(_M_X64) || defined(_M_ARM64) || defined (_M_IA64) + if (_BitScanReverse(&leading_zero, (uint32_t)(input_num >> 32))) + return (int)(63 - (leading_zero + 32)); + if (_BitScanReverse(&leading_zero, (uint32_t)input_num)) + return (int)(63 - leading_zero); +#endif // _WIN64 #else return __builtin_clzll(input_num); #endif // _MSC_VER