mirror of git://sourceware.org/git/glibc.git
50 lines
1.4 KiB
C
50 lines
1.4 KiB
C
/* ffs -- find first set bit in a word, counted from least significant end.
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For Intel 80x86, x>=3.
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This file is part of the GNU C Library.
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Copyright (C) 1991-2022 Free Software Foundation, Inc.
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The GNU C Library is free software; you can redistribute it and/or
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modify it under the terms of the GNU Lesser General Public
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License as published by the Free Software Foundation; either
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version 2.1 of the License, or (at your option) any later version.
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The GNU C Library is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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Lesser General Public License for more details.
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You should have received a copy of the GNU Lesser General Public
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License along with the GNU C Library; if not, see
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<https://www.gnu.org/licenses/>. */
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#define ffsl __something_else
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#include <string.h>
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#undef ffs
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#ifdef __GNUC__
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int
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__ffs (int x)
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{
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int cnt;
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int tmp;
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asm ("xorl %0,%0\n" /* Set CNT to zero. */
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"bsfl %2,%1\n" /* Count low bits in X and store in %1. */
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"jz 1f\n" /* Jump if OK, i.e. X was non-zero. */
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"leal 1(%1),%0\n" /* Return bsfl-result plus one on %0. */
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"1:" : "=&a" (cnt), "=r" (tmp) : "rm" (x));
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return cnt;
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}
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weak_alias (__ffs, ffs)
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libc_hidden_def (__ffs)
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libc_hidden_builtin_def (ffs)
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#undef ffsl
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weak_alias (__ffs, ffsl)
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#else
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#include <string/ffs.c>
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#endif
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