lh | 9ed821d | 2023-04-07 01:36:19 -0700 | [diff] [blame^] | 1 | /* ffs -- find first set bit in a word, counted from least significant end. |
| 2 | S/390 version. |
| 3 | Copyright (C) 2000-2015 Free Software Foundation, Inc. |
| 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 |
| 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. |
| 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 |
| 15 | Lesser General Public License for more details. |
| 16 | |
| 17 | You should have received a copy of the GNU Lesser General Public |
| 18 | License along with the GNU C Library; if not, see |
| 19 | <http://www.gnu.org/licenses/>. */ |
| 20 | |
| 21 | #include <limits.h> |
| 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 |
| 32 | __ffs (x) |
| 33 | int x; |
| 34 | { |
| 35 | int r; |
| 36 | |
| 37 | if (x == 0) |
| 38 | return 0; |
| 39 | __asm__(" lr %%r1,%1\n" |
| 40 | " sr %0,%0\n" |
| 41 | " tml %%r1,0xFFFF\n" |
| 42 | " jnz 0f\n" |
| 43 | " ahi %0,16\n" |
| 44 | " srl %%r1,16\n" |
| 45 | "0: tml %%r1,0x00FF\n" |
| 46 | " jnz 1f\n" |
| 47 | " ahi %0,8\n" |
| 48 | " srl %%r1,8\n" |
| 49 | "1: tml %%r1,0x000F\n" |
| 50 | " jnz 2f\n" |
| 51 | " ahi %0,4\n" |
| 52 | " srl %%r1,4\n" |
| 53 | "2: tml %%r1,0x0003\n" |
| 54 | " jnz 3f\n" |
| 55 | " ahi %0,2\n" |
| 56 | " srl %%r1,2\n" |
| 57 | "3: tml %%r1,0x0001\n" |
| 58 | " jnz 4f\n" |
| 59 | " ahi %0,1\n" |
| 60 | "4:" |
| 61 | : "=&d" (r) : "d" (x) : "cc", "1" ); |
| 62 | return r+1; |
| 63 | } |
| 64 | |
| 65 | weak_alias (__ffs, ffs) |
| 66 | libc_hidden_def (__ffs) |
| 67 | libc_hidden_builtin_def (ffs) |
| 68 | #if ULONG_MAX == UINT_MAX |
| 69 | #undef ffsl |
| 70 | weak_alias (__ffs, ffsl) |
| 71 | #endif |