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63 lines
1.8 KiB
C
63 lines
1.8 KiB
C
/* string-fzi.h -- zero byte detection; indices. Alpha version.
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Copyright (C) 2023-2024 Free Software Foundation, Inc.
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This file is part of the GNU C Library.
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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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<http://www.gnu.org/licenses/>. */
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#ifndef _STRING_FZI_H
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#define _STRING_FZI_H
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#include <stdint.h>
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#include <string-optype.h>
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#include <string-fza.h>
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/* Note that since CMPBGE creates a bit mask rather than a byte mask,
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we cannot simply provide a target-specific string-fza.h. */
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/* A subroutine for the index_zero functions. Given a bitmask C,
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return the index of the first bit set in memory order. */
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static __always_inline unsigned int
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index_first (find_t c)
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{
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#ifdef __alpha_cix__
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return __builtin_ctzl (c);
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#else
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c = c & -c;
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return (c & 0xf0 ? 4 : 0) + (c & 0xcc ? 2 : 0) + (c & 0xaa ? 1 : 0);
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#endif
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}
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/* Similarly, but return the (memory order) index of the last bit
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that is non-zero. Note that only the least 8 bits may be nonzero. */
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static __always_inline unsigned int
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index_last (find_t x)
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{
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#ifdef __alpha_cix__
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return __builtin_clzl (x) ^ 63;
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#else
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unsigned r = 0;
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if (x & 0xf0)
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r += 4;
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if (x & (0xc << r))
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r += 2;
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if (x & (0x2 << r))
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r += 1;
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return r;
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#endif
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}
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#endif /* _STRING_FZI_H */
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