1*6296500aSRobert Clausecker /* 2*6296500aSRobert Clausecker * Copyright (c) 2025 Robert Clausecker <fuz@FreeBSD.org> 3*6296500aSRobert Clausecker * 4*6296500aSRobert Clausecker * SPDX-License-Identifier: BSD-2-Clause 5*6296500aSRobert Clausecker */ 6*6296500aSRobert Clausecker 7*6296500aSRobert Clausecker #include <limits.h> 8*6296500aSRobert Clausecker #include <stdbit.h> 9*6296500aSRobert Clausecker 10*6296500aSRobert Clausecker unsigned int stdc_first_leading_zero_uc(unsigned char x)11*6296500aSRobert Clauseckerstdc_first_leading_zero_uc(unsigned char x) 12*6296500aSRobert Clausecker { 13*6296500aSRobert Clausecker const int offset = UINT_WIDTH - UCHAR_WIDTH; 14*6296500aSRobert Clausecker 15*6296500aSRobert Clausecker if (x == UCHAR_MAX) 16*6296500aSRobert Clausecker return (0); 17*6296500aSRobert Clausecker 18*6296500aSRobert Clausecker return (__builtin_clz(~(unsigned int)x << offset) + 1); 19*6296500aSRobert Clausecker } 20*6296500aSRobert Clausecker 21*6296500aSRobert Clausecker unsigned int stdc_first_leading_zero_us(unsigned short x)22*6296500aSRobert Clauseckerstdc_first_leading_zero_us(unsigned short x) 23*6296500aSRobert Clausecker { 24*6296500aSRobert Clausecker const int offset = UINT_WIDTH - USHRT_WIDTH; 25*6296500aSRobert Clausecker 26*6296500aSRobert Clausecker if (x == USHRT_MAX) 27*6296500aSRobert Clausecker return (0); 28*6296500aSRobert Clausecker 29*6296500aSRobert Clausecker return (__builtin_clz(~(unsigned int)x << offset) + 1); 30*6296500aSRobert Clausecker } 31*6296500aSRobert Clausecker 32*6296500aSRobert Clausecker unsigned int stdc_first_leading_zero_ui(unsigned int x)33*6296500aSRobert Clauseckerstdc_first_leading_zero_ui(unsigned int x) 34*6296500aSRobert Clausecker { 35*6296500aSRobert Clausecker if (x == ~0U) 36*6296500aSRobert Clausecker return (0); 37*6296500aSRobert Clausecker 38*6296500aSRobert Clausecker return (__builtin_clz(~x) + 1); 39*6296500aSRobert Clausecker } 40*6296500aSRobert Clausecker 41*6296500aSRobert Clausecker unsigned int stdc_first_leading_zero_ul(unsigned long x)42*6296500aSRobert Clauseckerstdc_first_leading_zero_ul(unsigned long x) 43*6296500aSRobert Clausecker { 44*6296500aSRobert Clausecker if (x == ~0UL) 45*6296500aSRobert Clausecker return (0); 46*6296500aSRobert Clausecker 47*6296500aSRobert Clausecker return (__builtin_clzl(~x) + 1); 48*6296500aSRobert Clausecker } 49*6296500aSRobert Clausecker 50*6296500aSRobert Clausecker unsigned int stdc_first_leading_zero_ull(unsigned long long x)51*6296500aSRobert Clauseckerstdc_first_leading_zero_ull(unsigned long long x) 52*6296500aSRobert Clausecker { 53*6296500aSRobert Clausecker if (x == ~0ULL) 54*6296500aSRobert Clausecker return (0); 55*6296500aSRobert Clausecker 56*6296500aSRobert Clausecker return (__builtin_clzll(~x) + 1); 57*6296500aSRobert Clausecker } 58