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