libs/unicode/unicode_tablookup.c

   1 /*
   2 ** Copyright 2011 Double Precision, Inc.
   3 ** See COPYING for distribution information.
   4 **
   5 */
   6
   7 #include        "unicode_config.h"
   8 #include        "unicode.h"
   9
  10 #define BLOCK_SIZE      256
  11
  12 uint8_t unicode_tab_lookup(unicode_char ch,
  13                            const size_t *unicode_indextab,
  14                            size_t unicode_indextab_sizeof,
  15                            const uint8_t (*unicode_rangetab)[2],
  16                            const uint8_t *unicode_classtab,
  17                            uint8_t uclass)
  18 {
  19         size_t cl=ch / BLOCK_SIZE;
  20
  21         if (cl < unicode_indextab_sizeof-1)
  22         {
  23                 const size_t start_pos=unicode_indextab[cl];
  24                 const uint8_t (*p)[2]=unicode_rangetab + start_pos;
  25                 size_t b=0, e=unicode_indextab[cl+1] - start_pos;
  26                 uint8_t chmodcl= ch & (BLOCK_SIZE-1);
  27
  28                 while (b < e)
  29                 {
  30                         size_t n=b + (e-b)/2;
  31
  32                         if (chmodcl >= p[n][0])
  33                         {
  34                                 if (chmodcl <= p[n][1])
  35                                 {
  36                                         uclass=unicode_classtab[start_pos+n];
  37                                         break;
  38                                 }
  39                                 b=n+1;
  40                         }
  41                         else
  42                         {
  43                                 e=n;
  44                         }
  45                 }
  46         }
  47
  48         return uclass;
  49 }