locale/coll-lookup.h

   1 /* Copyright (C) 2000 Free Software Foundation, Inc.
   2    This file is part of the GNU C Library.
   3    Contributed by Bruno Haible <haible@clisp.cons.org>, 2000.
   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, write to the Free
  17    Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
  18    02111-1307 USA.  */
  19
  20 /* Word tables are accessed by cutting wc in three blocks of bits:
  21    - the high 32-q-p bits,
  22    - the next q bits,
  23    - the next p bits.
  24
  25             +------------------+-----+-----+
  26      wc  =  +      32-q-p      |  q  |  p  |
  27             +------------------+-----+-----+
  28
  29    p and q are variable.  For 16-bit Unicode it is sufficient to
  30    choose p and q such that q+p <= 16.
  31
  32    The table contains the following uint32_t words:
  33    - q+p,
  34    - s = upper exclusive bound for wc >> (q+p),
  35    - p,
  36    - 2^q-1,
  37    - 2^p-1,
  38    - 1st-level table: s offsets, pointing into the 2nd-level table,
  39    - 2nd-level table: k*2^q offsets, pointing into the 3rd-level table,
  40    - 3rd-level table: j*2^p words, each containing 32 bits of data.
  41 */
  42
  43 #include <stdint.h>
  44
  45 /* Lookup in a table of int32_t, with default value 0.  */
  46 static inline int32_t
  47 collidx_table_lookup (const char *table, uint32_t wc)
  48 {
  49   uint32_t shift1 = ((const uint32_t *) table)[0];
  50   uint32_t index1 = wc >> shift1;
  51   uint32_t bound = ((const uint32_t *) table)[1];
  52   if (index1 < bound)
  53     {
  54       uint32_t lookup1 = ((const uint32_t *) table)[5 + index1];
  55       if (lookup1 != 0)
  56         {
  57           uint32_t shift2 = ((const uint32_t *) table)[2];
  58           uint32_t mask2 = ((const uint32_t *) table)[3];
  59           uint32_t index2 = (wc >> shift2) & mask2;
  60           uint32_t lookup2 = ((const uint32_t *)(table + lookup1))[index2];
  61           if (lookup2 != 0)
  62             {
  63               uint32_t mask3 = ((const uint32_t *) table)[4];
  64               uint32_t index3 = wc & mask3;
  65               int32_t lookup3 = ((const int32_t *)(table + lookup2))[index3];
  66
  67               return lookup3;
  68             }
  69         }
  70     }
  71   return 0;
  72 }
  73
  74 /* Lookup in a table of uint32_t, with default value 0xffffffff.  */
  75 static inline uint32_t
  76 collseq_table_lookup (const char *table, uint32_t wc)
  77 {
  78   uint32_t shift1 = ((const uint32_t *) table)[0];
  79   uint32_t index1 = wc >> shift1;
  80   uint32_t bound = ((const uint32_t *) table)[1];
  81   if (index1 < bound)
  82     {
  83       uint32_t lookup1 = ((const uint32_t *) table)[5 + index1];
  84       if (lookup1 != 0)
  85         {
  86           uint32_t shift2 = ((const uint32_t *) table)[2];
  87           uint32_t mask2 = ((const uint32_t *) table)[3];
  88           uint32_t index2 = (wc >> shift2) & mask2;
  89           uint32_t lookup2 = ((const uint32_t *)(table + lookup1))[index2];
  90           if (lookup2 != 0)
  91             {
  92               uint32_t mask3 = ((const uint32_t *) table)[4];
  93               uint32_t index3 = wc & mask3;
  94               uint32_t lookup3 = ((const uint32_t *)(table + lookup2))[index3];
  95
  96               return lookup3;
  97             }
  98         }
  99     }
 100   return ~((uint32_t) 0);
 101 }