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
57
58
59
60
61
62
63
64
65
66
67
68
69
|
/* ffs -- find first set bit in a word, counted from least significant end.
S/390 version.
Copyright (C) 2000-2024 Free Software Foundation, Inc.
This file is part of the GNU C Library.
The GNU C Library is free software; you can redistribute it and/or
modify it under the terms of the GNU Lesser General Public
License as published by the Free Software Foundation; either
version 2.1 of the License, or (at your option) any later version.
The GNU C Library is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
Lesser General Public License for more details.
You should have received a copy of the GNU Lesser General Public
License along with the GNU C Library; if not, see
<https://www.gnu.org/licenses/>. */
#include <limits.h>
#define ffsl __something_else
#include <string.h>
#undef ffs
/* ffs: find first bit set. This is defined the same way as
the libc and compiler builtin ffs routines, therefore
differs in spirit from the above ffz (man ffs). */
int
__ffs (int x)
{
int r;
if (x == 0)
return 0;
__asm__(" lr %%r1,%1\n"
" sr %0,%0\n"
" tml %%r1,0xFFFF\n"
" jnz 0f\n"
" ahi %0,16\n"
" srl %%r1,16\n"
"0: tml %%r1,0x00FF\n"
" jnz 1f\n"
" ahi %0,8\n"
" srl %%r1,8\n"
"1: tml %%r1,0x000F\n"
" jnz 2f\n"
" ahi %0,4\n"
" srl %%r1,4\n"
"2: tml %%r1,0x0003\n"
" jnz 3f\n"
" ahi %0,2\n"
" srl %%r1,2\n"
"3: tml %%r1,0x0001\n"
" jnz 4f\n"
" ahi %0,1\n"
"4:"
: "=&d" (r) : "d" (x) : "cc", "1" );
return r+1;
}
weak_alias (__ffs, ffs)
libc_hidden_def (__ffs)
libc_hidden_builtin_def (ffs)
#if ULONG_MAX == UINT_MAX
#undef ffsl
weak_alias (__ffs, ffsl)
#endif
|
