blob: c1a0e6b991da139106626253c7c54b62e6f056a6 (
plain) (
blame)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
|
/*
* Copyright (c) 2025 Robert Clausecker <fuz@FreeBSD.org>
*
* SPDX-License-Identifier: BSD-2-Clause
*/
#include <assert.h>
#include <limits.h>
#include <stdbit.h>
/* Avoid triggering undefined behavior if x == ~0. */
static_assert(UCHAR_WIDTH < UINT_WIDTH,
"stdc_trailing_ones_uc needs UCHAR_WIDTH < UINT_WIDTH");
unsigned int
stdc_trailing_ones_uc(unsigned char x)
{
return (__builtin_ctz(~x));
}
/* Avoid triggering undefined behavior if x == ~0. */
static_assert(USHRT_WIDTH < UINT_WIDTH,
"stdc_trailing_ones_uc needs USHRT_WIDTH < UINT_WIDTH");
unsigned int
stdc_trailing_ones_us(unsigned short x)
{
return (__builtin_ctz(~x));
}
unsigned int
stdc_trailing_ones_ui(unsigned int x)
{
if (x == ~0U)
return (UINT_WIDTH);
return (__builtin_ctz(~x));
}
unsigned int
stdc_trailing_ones_ul(unsigned long x)
{
if (x == ~0UL)
return (ULONG_WIDTH);
return (__builtin_ctzl(~x));
}
unsigned int
stdc_trailing_ones_ull(unsigned long long x)
{
if (x == ~0ULL)
return (ULLONG_WIDTH);
return (__builtin_ctzll(~x));
}
|
