lib/unictype/blocks.c

   1 /* Blocks of Unicode characters.
   2    Copyright (C) 2007, 2009-2021 Free Software Foundation, Inc.
   3    Written by Bruno Haible <bruno@clisp.org>, 2007.
   4
   5    This program is free software: you can redistribute it and/or modify it
   6    under the terms of the GNU Lesser General Public License as published
   7    by the Free Software Foundation; either version 3 of the License, or
   8    (at your option) any later version.
   9
  10    This program 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 License
  16    along with this program.  If not, see <https://www.gnu.org/licenses/>.  */
  17
  18 #include <config.h>
  19
  20 /* Specification.  */
  21 #include "unictype.h"
  22
  23 #include "blocks.h"
  24
  25 const uc_block_t *
  26 uc_block (ucs4_t uc)
  27 {
  28   unsigned int first_index;
  29   unsigned int last_index;
  30
  31   if (uc < blocks_level1_threshold)
  32     {
  33       unsigned int index1 = uc >> blocks_level1_shift;
  34       first_index = blocks_level1[2 * index1];
  35       last_index = blocks_level1[2 * index1 + 1];
  36     }
  37   else
  38     {
  39       first_index = blocks_upper_first_index;
  40       last_index = blocks_upper_last_index;
  41     }
  42   /* We know that the relevant blocks are blocks[i] with
  43      first_index <= i < last_index.  Now perform a binary search.  */
  44   while (first_index < last_index)
  45     {
  46       unsigned int mid_index = (first_index + last_index) / 2;
  47       if (blocks[mid_index].end < uc)
  48         first_index = mid_index + 1;
  49       else if (uc < blocks[mid_index].start)
  50         last_index = mid_index;
  51       else
  52         return &blocks[mid_index];
  53     }
  54   return NULL;
  55 }
  56
  57 void
  58 uc_all_blocks (const uc_block_t **blocksp, size_t *countp)
  59 {
  60   *blocksp = blocks;
  61   *countp = sizeof (blocks) / sizeof (blocks[0]);
  62 }