1/* Canonical composition of Unicode characters.
2   Copyright (C) 2002, 2006, 2009-2010 Free Software Foundation, Inc.
3   Written by Bruno Haible <bruno@clisp.org>, 2009.
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 <http://www.gnu.org/licenses/>.  */
17
18#include <config.h>
19
20/* Specification.  */
21#include "uninorm.h"
22
23#include <string.h>
24
25struct composition_rule { char codes[4]; unsigned short combined; };
26
27#include "composition-table.h"
28
29ucs4_t
30uc_composition (ucs4_t uc1, ucs4_t uc2)
31{
32  if (uc1 < 0x10000 && uc2 < 0x10000)
33    {
34      if (uc2 >= 0x1161 && uc2 < 0x1161 + 21
35          && uc1 >= 0x1100 && uc1 < 0x1100 + 19)
36        {
37          /* Hangul: Combine single letter L and single letter V to form
38             two-letter syllable LV.  */
39          return 0xAC00 + ((uc1 - 0x1100) * 21 + (uc2 - 0x1161)) * 28;
40        }
41      else if (uc2 > 0x11A7 && uc2 < 0x11A7 + 28
42               && uc1 >= 0xAC00 && uc1 < 0xD7A4 && ((uc1 - 0xAC00) % 28) == 0)
43        {
44          /* Hangul: Combine two-letter syllable LV with single-letter T
45             to form three-letter syllable LVT.  */
46          return uc1 + (uc2 - 0x11A7);
47        }
48      else
49        {
50#if 0
51          unsigned int uc = MUL1 * uc1 * MUL2 * uc2;
52          unsigned int index1 = uc >> composition_header_0;
53          if (index1 < composition_header_1)
54            {
55              int lookup1 = u_composition.level1[index1];
56              if (lookup1 >= 0)
57                {
58                  unsigned int index2 = (uc >> composition_header_2) & composition_header_3;
59                  int lookup2 = u_composition.level2[lookup1 + index2];
60                  if (lookup2 >= 0)
61                    {
62                      unsigned int index3 = (uc & composition_header_4);
63                      unsigned int lookup3 = u_composition.level3[lookup2 + index3];
64                      if ((lookup3 >> 16) == uc2)
65                        return lookup3 & ((1U << 16) - 1);
66                    }
67                }
68            }
69#else
70          char codes[4];
71          const struct composition_rule *rule;
72
73          codes[0] = (uc1 >> 8) & 0xff;
74          codes[1] = uc1 & 0xff;
75          codes[2] = (uc2 >> 8) & 0xff;
76          codes[3] = uc2 & 0xff;
77
78          rule = gl_uninorm_compose_lookup (codes, 4);
79          if (rule != NULL)
80            return rule->combined;
81#endif
82        }
83    }
84  return 0;
85}
86