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b8a8413c UD |
1 | /* ffs -- find first set bit in a word, counted from least significant end. |
2 | S/390 version. | |
2b778ceb | 3 | Copyright (C) 2000-2021 Free Software Foundation, Inc. |
b8a8413c UD |
4 | Contributed by Martin Schwidefsky (schwidefsky@de.ibm.com). |
5 | This file is part of the GNU C Library. | |
6 | ||
7 | The GNU C Library is free software; you can redistribute it and/or | |
41bdb6e2 AJ |
8 | modify it under the terms of the GNU Lesser General Public |
9 | License as published by the Free Software Foundation; either | |
10 | version 2.1 of the License, or (at your option) any later version. | |
b8a8413c UD |
11 | |
12 | The GNU C Library is distributed in the hope that it will be useful, | |
13 | but WITHOUT ANY WARRANTY; without even the implied warranty of | |
14 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU | |
41bdb6e2 | 15 | Lesser General Public License for more details. |
b8a8413c | 16 | |
41bdb6e2 | 17 | You should have received a copy of the GNU Lesser General Public |
59ba27a6 | 18 | License along with the GNU C Library; if not, see |
5a82c748 | 19 | <https://www.gnu.org/licenses/>. */ |
b8a8413c | 20 | |
f93fa7d4 | 21 | #include <limits.h> |
b8a8413c UD |
22 | #define ffsl __something_else |
23 | #include <string.h> | |
24 | ||
25 | #undef ffs | |
26 | ||
27 | /* ffs: find first bit set. This is defined the same way as | |
28 | the libc and compiler builtin ffs routines, therefore | |
29 | differs in spirit from the above ffz (man ffs). */ | |
30 | ||
31 | int | |
bd2260a2 | 32 | __ffs (int x) |
b8a8413c UD |
33 | { |
34 | int r; | |
35 | ||
36 | if (x == 0) | |
37 | return 0; | |
38 | __asm__(" lr %%r1,%1\n" | |
39 | " sr %0,%0\n" | |
40 | " tml %%r1,0xFFFF\n" | |
41 | " jnz 0f\n" | |
42 | " ahi %0,16\n" | |
43 | " srl %%r1,16\n" | |
44 | "0: tml %%r1,0x00FF\n" | |
45 | " jnz 1f\n" | |
46 | " ahi %0,8\n" | |
47 | " srl %%r1,8\n" | |
48 | "1: tml %%r1,0x000F\n" | |
49 | " jnz 2f\n" | |
50 | " ahi %0,4\n" | |
51 | " srl %%r1,4\n" | |
52 | "2: tml %%r1,0x0003\n" | |
53 | " jnz 3f\n" | |
54 | " ahi %0,2\n" | |
55 | " srl %%r1,2\n" | |
56 | "3: tml %%r1,0x0001\n" | |
57 | " jnz 4f\n" | |
58 | " ahi %0,1\n" | |
f93fa7d4 | 59 | "4:" |
b8a8413c UD |
60 | : "=&d" (r) : "d" (x) : "cc", "1" ); |
61 | return r+1; | |
62 | } | |
63 | ||
64 | weak_alias (__ffs, ffs) | |
5bb43a43 | 65 | libc_hidden_def (__ffs) |
2dd18ce2 | 66 | libc_hidden_builtin_def (ffs) |
7906dd56 | 67 | #if ULONG_MAX == UINT_MAX |
b8a8413c UD |
68 | #undef ffsl |
69 | weak_alias (__ffs, ffsl) | |
7906dd56 | 70 | #endif |