1/* Decomposition of Unicode characters.
2   Copyright (C) 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 "decomposition-table.h"
24
25int
26uc_decomposition (ucs4_t uc, int *decomp_tag, ucs4_t *decomposition)
27{
28  if (uc >= 0xAC00 && uc < 0xD7A4)
29    {
30      /* Hangul syllable.  See Unicode standard, chapter 3, section
31         "Hangul Syllable Decomposition",  See also the clarification at
32         <http://www.unicode.org/versions/Unicode5.1.0/>, section
33         "Clarification of Hangul Jamo Handling".  */
34      unsigned int t;
35
36      uc -= 0xAC00;
37      t = uc % 28;
38
39      *decomp_tag = UC_DECOMP_CANONICAL;
40      if (t == 0)
41        {
42          unsigned int v, l;
43
44          uc = uc / 28;
45          v = uc % 21;
46          l = uc / 21;
47
48          decomposition[0] = 0x1100 + l;
49          decomposition[1] = 0x1161 + v;
50          return 2;
51        }
52      else
53        {
54#if 1 /* Return the pairwise decomposition, not the full decomposition.  */
55          decomposition[0] = 0xAC00 + uc - t; /* = 0xAC00 + (l * 21 + v) * 28; */
56          decomposition[1] = 0x11A7 + t;
57          return 2;
58#else
59          unsigned int v, l;
60
61          uc = uc / 28;
62          v = uc % 21;
63          l = uc / 21;
64
65          decomposition[0] = 0x1100 + l;
66          decomposition[1] = 0x1161 + v;
67          decomposition[2] = 0x11A7 + t;
68          return 3;
69#endif
70        }
71    }
72  else if (uc < 0x110000)
73    {
74      unsigned short entry = decomp_index (uc);
75      if (entry != (unsigned short)(-1))
76        {
77          const unsigned char *p;
78          unsigned int element;
79          unsigned int length;
80
81          p = &gl_uninorm_decomp_chars_table[3 * (entry & 0x7FFF)];
82          element = (p[0] << 16) | (p[1] << 8) | p[2];
83          /* The first element has 5 bits for the decomposition type.  */
84          *decomp_tag = (element >> 18) & 0x1f;
85          length = 1;
86          for (;;)
87            {
88              /* Every element has an 18 bits wide Unicode code point.  */
89              *decomposition = element & 0x3ffff;
90              /* Bit 23 tells whether there are more elements,  */
91              if ((element & (1 << 23)) == 0)
92                break;
93              p += 3;
94              element = (p[0] << 16) | (p[1] << 8) | p[2];
95              decomposition++;
96              length++;
97            }
98          return length;
99        }
100    }
101  return -1;
102}
103