locale/weight.h

   1 /* Copyright (C) 1996-2015 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 #ifndef _WEIGHT_H_
  20 #define _WEIGHT_H_      1
  21
  22 /* Find index of weight.  */
  23 static inline int32_t __attribute__ ((always_inline))
  24 findidx (const int32_t *table,
  25          const int32_t *indirect,
  26          const unsigned char *extra,
  27          const unsigned char **cpp, size_t len)
  28 {
  29   int_fast32_t i = table[*(*cpp)++];
  30   const unsigned char *cp;
  31   const unsigned char *usrc;
  32
  33   if (i >= 0)
  34     /* This is an index into the weight table.  Cool.  */
  35     return i;
  36
  37   /* Oh well, more than one sequence starting with this byte.
  38      Search for the correct one.  */
  39   cp = &extra[-i];
  40   usrc = *cpp;
  41   --len;
  42   while (1)
  43     {
  44       size_t nhere;
  45
  46       /* The first thing is the index.  */
  47       i = *((const int32_t *) cp);
  48       cp += sizeof (int32_t);
  49
  50       /* Next is the length of the byte sequence.  These are always
  51          short byte sequences so there is no reason to call any
  52          function (even if they are inlined).  */
  53       nhere = *cp++;
  54
  55       if (i >= 0)
  56         {
  57           /* It is a single character.  If it matches we found our
  58              index.  Note that at the end of each list there is an
  59              entry of length zero which represents the single byte
  60              sequence.  The first (and here only) byte was tested
  61              already.  */
  62           size_t cnt;
  63
  64           for (cnt = 0; cnt < nhere && cnt < len; ++cnt)
  65             if (cp[cnt] != usrc[cnt])
  66               break;
  67
  68           if (cnt == nhere)
  69             {
  70               /* Found it.  */
  71               *cpp += nhere;
  72               return i;
  73             }
  74
  75           /* Up to the next entry.  */
  76           cp += nhere;
  77           if (!LOCFILE_ALIGNED_P (1 + nhere))
  78             cp += LOCFILE_ALIGN - (1 + nhere) % LOCFILE_ALIGN;
  79         }
  80       else
  81         {
  82           /* This is a range of characters.  First decide whether the
  83              current byte sequence lies in the range.  */
  84           size_t cnt;
  85           size_t offset = 0;
  86
  87           for (cnt = 0; cnt < nhere && cnt < len; ++cnt)
  88             if (cp[cnt] != usrc[cnt])
  89               break;
  90
  91           if (cnt != nhere)
  92             {
  93               if (cnt == len || cp[cnt] > usrc[cnt])
  94                 {
  95                   /* Cannot be in this range.  */
  96                   cp += 2 * nhere;
  97                   if (!LOCFILE_ALIGNED_P (1 + 2 * nhere))
  98                     cp += (LOCFILE_ALIGN
  99                            - (1 + 2 * nhere) % LOCFILE_ALIGN);
 100                   continue;
 101                 }
 102
 103               /* Test against the end of the range.  */
 104               for (cnt = 0; cnt < nhere; ++cnt)
 105                 if (cp[nhere + cnt] != usrc[cnt])
 106                   break;
 107
 108               if (cnt != nhere && cp[nhere + cnt] < usrc[cnt])
 109                 {
 110                   /* Cannot be in this range.  */
 111                   cp += 2 * nhere;
 112                   if (!LOCFILE_ALIGNED_P (1 + 2 * nhere))
 113                     cp += (LOCFILE_ALIGN
 114                            - (1 + 2 * nhere) % LOCFILE_ALIGN);
 115                   continue;
 116                 }
 117
 118               /* This range matches the next characters.  Now find
 119                  the offset in the indirect table.  */
 120               for (cnt = 0; cp[cnt] == usrc[cnt]; ++cnt);
 121
 122               do
 123                 {
 124                   offset <<= 8;
 125                   offset += usrc[cnt] - cp[cnt];
 126                 }
 127               while (++cnt < nhere);
 128             }
 129
 130           *cpp += nhere;
 131           return indirect[-i + offset];
 132         }
 133     }
 134
 135   /* NOTREACHED */
 136   return 0x43219876;
 137 }
 138
 139 #endif  /* weight.h */