| 1 | /* ffs -- find first set bit in a word, counted from least significant end. |
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| 2 | S/390 version. |
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| 3 | Copyright (C) 2000-2022 Free Software Foundation, Inc. |
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| 4 | This file is part of the GNU C Library. |
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| 5 | |
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| 6 | The GNU C Library is free software; you can redistribute it and/or |
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| 7 | modify it under the terms of the GNU Lesser General Public |
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| 8 | License as published by the Free Software Foundation; either |
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| 9 | version 2.1 of the License, or (at your option) any later version. |
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| 10 | |
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| 11 | The GNU C Library is distributed in the hope that it will be useful, |
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| 12 | but WITHOUT ANY WARRANTY; without even the implied warranty of |
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| 13 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU |
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| 14 | Lesser General Public License for more details. |
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| 15 | |
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| 16 | You should have received a copy of the GNU Lesser General Public |
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| 17 | License along with the GNU C Library; if not, see |
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| 18 | <https://www.gnu.org/licenses/>. */ |
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| 19 | |
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| 20 | #include <limits.h> |
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| 21 | #define ffsl __something_else |
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| 22 | #include <string.h> |
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| 23 | |
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| 24 | #undef ffs |
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| 25 | |
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| 26 | /* ffs: find first bit set. This is defined the same way as |
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| 27 | the libc and compiler builtin ffs routines, therefore |
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| 28 | differs in spirit from the above ffz (man ffs). */ |
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| 29 | |
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| 30 | int |
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| 31 | __ffs (int x) |
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| 32 | { |
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| 33 | int r; |
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| 34 | |
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| 35 | if (x == 0) |
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| 36 | return 0; |
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| 37 | __asm__(" lr %%r1,%1\n" |
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| 38 | " sr %0,%0\n" |
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| 39 | " tml %%r1,0xFFFF\n" |
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| 40 | " jnz 0f\n" |
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| 41 | " ahi %0,16\n" |
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| 42 | " srl %%r1,16\n" |
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| 43 | "0: tml %%r1,0x00FF\n" |
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| 44 | " jnz 1f\n" |
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| 45 | " ahi %0,8\n" |
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| 46 | " srl %%r1,8\n" |
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| 47 | "1: tml %%r1,0x000F\n" |
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| 48 | " jnz 2f\n" |
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| 49 | " ahi %0,4\n" |
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| 50 | " srl %%r1,4\n" |
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| 51 | "2: tml %%r1,0x0003\n" |
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| 52 | " jnz 3f\n" |
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| 53 | " ahi %0,2\n" |
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| 54 | " srl %%r1,2\n" |
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| 55 | "3: tml %%r1,0x0001\n" |
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| 56 | " jnz 4f\n" |
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| 57 | " ahi %0,1\n" |
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| 58 | "4:" |
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| 59 | : "=&d" (r) : "d" (x) : "cc" , "1" ); |
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| 60 | return r+1; |
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| 61 | } |
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| 62 | |
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| 63 | weak_alias (__ffs, ffs) |
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| 64 | libc_hidden_def (__ffs) |
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| 65 | libc_hidden_builtin_def (ffs) |
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| 66 | #if ULONG_MAX == UINT_MAX |
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| 67 | #undef ffsl |
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| 68 | weak_alias (__ffs, ffsl) |
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| 69 | #endif |
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| 70 | |
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