xref: /freebsd/lib/libc/stdbit/stdc_first_trailing_one.c (revision 6296500a85c8474e3ff3fe2f8e4a9d56dd0acd64) 
1 /*
2  * Copyright (c) 2025 Robert Clausecker <fuz@FreeBSD.org>
3  *
4  * SPDX-License-Identifier: BSD-2-Clause
5  */
6 
7 #include <stdbit.h>
8 
9 unsigned int
stdc_first_trailing_one_uc(unsigned char x)10 stdc_first_trailing_one_uc(unsigned char x)
11 {
12 	if (x == 0)
13 		return (0);
14 
15 	return (__builtin_ctz(x) + 1);
16 }
17 
18 unsigned int
stdc_first_trailing_one_us(unsigned short x)19 stdc_first_trailing_one_us(unsigned short x)
20 {
21 	if (x == 0)
22 		return (0);
23 
24 	return (__builtin_ctz(x) + 1);
25 }
26 
27 unsigned int
stdc_first_trailing_one_ui(unsigned int x)28 stdc_first_trailing_one_ui(unsigned int x)
29 {
30 	if (x == 0)
31 		return (0);
32 
33 	return (__builtin_ctz(x) + 1);
34 }
35 
36 unsigned int
stdc_first_trailing_one_ul(unsigned long x)37 stdc_first_trailing_one_ul(unsigned long x)
38 {
39 	if (x == 0)
40 		return (0);
41 
42 	return (__builtin_ctzl(x) + 1);
43 }
44 
45 unsigned int
stdc_first_trailing_one_ull(unsigned long long x)46 stdc_first_trailing_one_ull(unsigned long long x)
47 {
48 	if (x == 0)
49 		return (0);
50 
51 	return (__builtin_ctzll(x) + 1);
52 }
53