sysdeps/alpha/string-fzi.h

   1 /* string-fzi.h -- zero byte detection; indices.  Alpha version.
   2    Copyright (C) 2023 Free Software Foundation, Inc.
   3    This file is part of the GNU C Library.
   4
   5    The GNU C Library is free software; you can redistribute it and/or
   6    modify it under the terms of the GNU Lesser General Public
   7    License as published by the Free Software Foundation; either
   8    version 2.1 of the License, or (at your option) any later version.
   9
  10    The GNU C Library is distributed in the hope that it will be useful,
  11    but WITHOUT ANY WARRANTY; without even the implied warranty of
  12    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  13    Lesser General Public License for more details.
  14
  15    You should have received a copy of the GNU Lesser General Public
  16    License along with the GNU C Library; if not, see
  17    <http://www.gnu.org/licenses/>.  */
  18
  19 #ifndef _STRING_FZI_H
  20 #define _STRING_FZI_H
  21
  22 #include <stdint.h>
  23 #include <string-optype.h>
  24 #include <string-fza.h>
  25
  26 /* Note that since CMPBGE creates a bit mask rather than a byte mask,
  27    we cannot simply provide a target-specific string-fza.h.  */
  28
  29 /* A subroutine for the index_zero functions.  Given a bitmask C,
  30    return the index of the first bit set in memory order.  */
  31 static __always_inline unsigned int
  32 index_first (find_t c)
  33 {
  34 #ifdef __alpha_cix__
  35   return __builtin_ctzl (c);
  36 #else
  37   c = c & -c;
  38   return (c & 0xf0 ? 4 : 0) + (c & 0xcc ? 2 : 0) + (c & 0xaa ? 1 : 0);
  39 #endif
  40 }
  41
  42 /* Similarly, but return the (memory order) index of the last bit
  43    that is non-zero.  Note that only the least 8 bits may be nonzero.  */
  44
  45 static __always_inline unsigned int
  46 index_last (find_t x)
  47 {
  48 #ifdef __alpha_cix__
  49   return __builtin_clzl (x) ^ 63;
  50 #else
  51   unsigned r = 0;
  52   if (x & 0xf0)
  53     r += 4;
  54   if (x & (0xc << r))
  55     r += 2;
  56   if (x & (0x2 << r))
  57     r += 1;
  58   return r;
  59 #endif
  60 }
  61
  62 #endif /* _STRING_FZI_H */