locale/weightwc.h

   1 /* Copyright (C) 1996-2021 Free Software Foundation, Inc.
   2    This file is part of the GNU C Library.
   3    Written by Ulrich Drepper, <drepper@cygnus.com>.
   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    <https://www.gnu.org/licenses/>.  */
  18
  19 #ifndef _WEIGHTWC_H_
  20 #define _WEIGHTWC_H_    1
  21
  22 #include <libc-diag.h>
  23
  24 /* Find index of weight.  */
  25 static inline int32_t __attribute__ ((always_inline))
  26 findidx (const int32_t *table,
  27          const int32_t *indirect,
  28          const wint_t *extra,
  29          const wint_t **cpp, size_t len)
  30 {
  31   /* With GCC 7 when compiling with -Os the compiler warns that
  32      seq1.back_us and seq2.back_us, which become *cpp, might be used
  33      uninitialized.  This is impossible as this function cannot be
  34      called except in cases where those fields have been
  35      initialized.  */
  36   DIAG_PUSH_NEEDS_COMMENT;
  37   DIAG_IGNORE_Os_NEEDS_COMMENT (7, "-Wmaybe-uninitialized");
  38   wint_t ch = *(*cpp)++;
  39   DIAG_POP_NEEDS_COMMENT;
  40   int32_t i = __collidx_table_lookup ((const char *) table, ch);
  41
  42   if (i >= 0)
  43     /* This is an index into the weight table.  Cool.  */
  44     return i;
  45
  46   /* Oh well, more than one sequence starting with this byte.
  47      Search for the correct one.  */
  48   const int32_t *cp = (const int32_t *) &extra[-i];
  49   --len;
  50   while (1)
  51     {
  52       size_t nhere;
  53       const int32_t *usrc = (const int32_t *) *cpp;
  54
  55       /* The first thing is the index.  */
  56       i = *cp++;
  57
  58       /* Next is the length of the byte sequence.  These are always
  59          short byte sequences so there is no reason to call any
  60          function (even if they are inlined).  */
  61       nhere = *cp++;
  62
  63       if (i >= 0)
  64         {
  65           /* It is a single character.  If it matches we found our
  66              index.  Note that at the end of each list there is an
  67              entry of length zero which represents the single byte
  68              sequence.  The first (and here only) byte was tested
  69              already.  */
  70           size_t cnt;
  71
  72           /* With GCC 5.3 when compiling with -Os the compiler warns
  73              that seq2.back_us, which becomes usrc, might be used
  74              uninitialized.  This can't be true because we pass a length
  75              of -1 for len at the same time which means that this loop
  76              never executes.  */
  77           DIAG_PUSH_NEEDS_COMMENT;
  78           DIAG_IGNORE_Os_NEEDS_COMMENT (5, "-Wmaybe-uninitialized");
  79           for (cnt = 0; cnt < nhere && cnt < len; ++cnt)
  80             if (cp[cnt] != usrc[cnt])
  81               break;
  82           DIAG_POP_NEEDS_COMMENT;
  83
  84           if (cnt == nhere)
  85             {
  86               /* Found it.  */
  87               *cpp += nhere;
  88               return i;
  89             }
  90
  91           /* Up to the next entry.  */
  92           cp += nhere;
  93         }
  94       else
  95         {
  96           /* This is a range of characters.  First decide whether the
  97              current byte sequence lies in the range.  */
  98           size_t cnt;
  99           size_t offset;
 100
 101           /* With GCC 7 when compiling with -Os the compiler warns
 102              that seq1.back_us and seq2.back_us, which become usrc,
 103              might be used uninitialized.  This is impossible for the
 104              same reason as described above.  */
 105           DIAG_PUSH_NEEDS_COMMENT;
 106           DIAG_IGNORE_Os_NEEDS_COMMENT (7, "-Wmaybe-uninitialized");
 107           for (cnt = 0; cnt < nhere - 1 && cnt < len; ++cnt)
 108             if (cp[cnt] != usrc[cnt])
 109               break;
 110           DIAG_POP_NEEDS_COMMENT;
 111
 112           if (cnt < nhere - 1 || cnt == len)
 113             {
 114               cp += 2 * nhere;
 115               continue;
 116             }
 117
 118           /* With GCC 7 when compiling with -Os the compiler warns
 119              that seq1.back_us and seq2.back_us, which become usrc,
 120              might be used uninitialized.  This is impossible for the
 121              same reason as described above.  */
 122           DIAG_PUSH_NEEDS_COMMENT;
 123           DIAG_IGNORE_Os_NEEDS_COMMENT (7, "-Wmaybe-uninitialized");
 124           if (cp[nhere - 1] > usrc[nhere - 1])
 125             {
 126               cp += 2 * nhere;
 127               continue;
 128             }
 129           DIAG_POP_NEEDS_COMMENT;
 130
 131           if (cp[2 * nhere - 1] < usrc[nhere - 1])
 132             {
 133               cp += 2 * nhere;
 134               continue;
 135             }
 136
 137           /* This range matches the next characters.  Now find
 138              the offset in the indirect table.  */
 139           offset = usrc[nhere - 1] - cp[nhere - 1];
 140           *cpp += nhere;
 141
 142           return indirect[-i + offset];
 143         }
 144     }
 145
 146   /* NOTREACHED */
 147   return 0x43219876;
 148 }
 149
 150 #endif  /* weightwc.h */