locale/weight.h

   1 /* Copyright (C) 1996-2013 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    <http://www.gnu.org/licenses/>.  */
  18
  19 /* Find index of weight.  */
  20 auto inline int32_t
  21 __attribute ((always_inline))
  22 findidx (const unsigned char **cpp, size_t len)
  23 {
  24   int_fast32_t i = table[*(*cpp)++];
  25   const unsigned char *cp;
  26   const unsigned char *usrc;
  27
  28   if (i >= 0)
  29     /* This is an index into the weight table.  Cool.  */
  30     return i;
  31
  32   /* Oh well, more than one sequence starting with this byte.
  33      Search for the correct one.  */
  34   cp = &extra[-i];
  35   usrc = *cpp;
  36   --len;
  37   while (1)
  38     {
  39       size_t nhere;
  40
  41       /* The first thing is the index.  */
  42       i = *((const int32_t *) cp);
  43       cp += sizeof (int32_t);
  44
  45       /* Next is the length of the byte sequence.  These are always
  46          short byte sequences so there is no reason to call any
  47          function (even if they are inlined).  */
  48       nhere = *cp++;
  49
  50       if (i >= 0)
  51         {
  52           /* It is a single character.  If it matches we found our
  53              index.  Note that at the end of each list there is an
  54              entry of length zero which represents the single byte
  55              sequence.  The first (and here only) byte was tested
  56              already.  */
  57           size_t cnt;
  58
  59           for (cnt = 0; cnt < nhere && cnt < len; ++cnt)
  60             if (cp[cnt] != usrc[cnt])
  61               break;
  62
  63           if (cnt == nhere)
  64             {
  65               /* Found it.  */
  66               *cpp += nhere;
  67               return i;
  68             }
  69
  70           /* Up to the next entry.  */
  71           cp += nhere;
  72           if ((1 + nhere) % __alignof__ (int32_t) != 0)
  73             cp += __alignof__ (int32_t) - (1 + nhere) % __alignof__ (int32_t);
  74         }
  75       else
  76         {
  77           /* This is a range of characters.  First decide whether the
  78              current byte sequence lies in the range.  */
  79           size_t cnt;
  80           size_t offset = 0;
  81
  82           for (cnt = 0; cnt < nhere && cnt < len; ++cnt)
  83             if (cp[cnt] != usrc[cnt])
  84               break;
  85
  86           if (cnt != nhere)
  87             {
  88               if (cnt == len || cp[cnt] > usrc[cnt])
  89                 {
  90                   /* Cannot be in this range.  */
  91                   cp += 2 * nhere;
  92                   if ((1 + 2 * nhere) % __alignof__ (int32_t) != 0)
  93                     cp += (__alignof__ (int32_t)
  94                            - (1 + 2 * nhere) % __alignof__ (int32_t));
  95                   continue;
  96                 }
  97
  98               /* Test against the end of the range.  */
  99               for (cnt = 0; cnt < nhere; ++cnt)
 100                 if (cp[nhere + cnt] != usrc[cnt])
 101                   break;
 102
 103               if (cnt != nhere && cp[nhere + cnt] < usrc[cnt])
 104                 {
 105                   /* Cannot be in this range.  */
 106                   cp += 2 * nhere;
 107                   if ((1 + 2 * nhere) % __alignof__ (int32_t) != 0)
 108                     cp += (__alignof__ (int32_t)
 109                            - (1 + 2 * nhere) % __alignof__ (int32_t));
 110                   continue;
 111                 }
 112
 113               /* This range matches the next characters.  Now find
 114                  the offset in the indirect table.  */
 115               for (cnt = 0; cp[cnt] == usrc[cnt]; ++cnt);
 116
 117               do
 118                 {
 119                   offset <<= 8;
 120                   offset += usrc[cnt] - cp[cnt];
 121                 }
 122               while (++cnt < nhere);
 123             }
 124
 125           *cpp += nhere;
 126           return indirect[-i + offset];
 127         }
 128     }
 129
 130   /* NOTREACHED */
 131   return 0x43219876;
 132 }