1/*
2 * Copyright (C) 1999-2001, 2007 Free Software Foundation, Inc.
3 * This file is part of the GNU LIBICONV Library.
4 *
5 * The GNU LIBICONV Library is free software; you can redistribute it
6 * and/or modify it under the terms of the GNU Library General Public
7 * License as published by the Free Software Foundation; either version 2
8 * of the License, or (at your option) any later version.
9 *
10 * The GNU LIBICONV Library is distributed in the hope that it will be
11 * useful, but WITHOUT ANY WARRANTY; without even the implied warranty of
12 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
13 * Library General Public License for more details.
14 *
15 * You should have received a copy of the GNU Library General Public
16 * License along with the GNU LIBICONV Library; see the file COPYING.LIB.
17 * If not, write to the Free Software Foundation, Inc., 51 Franklin Street,
18 * Fifth Floor, Boston, MA 02110-1301, USA.
19 */
20
21/*
22 * JOHAB
23 */
24
25/*
26   Conversion between JOHAB codes (s1,s2) and KSX1001 codes (c1,c2):
27   Example. (s1,s2) = 0xD931, (c1,c2) = 0x2121.
28            (s1,s2) = 0xDEF1, (c1,c2) = 0x2C71.
29            (s1,s2) = 0xE031, (c1,c2) = 0x4A21.
30            (s1,s2) = 0xF9FE, (c1,c2) = 0x7D7E.
31   0xD9 <= s1 <= 0xDE || 0xE0 <= s1 <= 0xF9,
32   0x31 <= s2 <= 0x7E || 0x91 <= s2 <= 0xFE,
33   0x21 <= c1 <= 0x2C || 0x4A <= c1 <= 0x7D,
34   0x21 <= c2 <= 0x7E.
35   Invariant:
36     94*(s1 < 0xE0 ? 2*s1-0x1B2 : 2*s1-0x197) + (s2 < 0x91 ? s2-0x31 : s2-0x43)
37     = 94*(c1-0x21)+(c2-0x21)
38   Conversion (s1,s2) -> (c1,c2):
39     t1 := (s1 < 0xE0 ? 2*s1-0x1B2 : 2*s1-0x197)
40     t2 := (s2 < 0x91 ? s2-0x31 : s2-0x43)
41     c1 := t1 + (t2 < 0x5E ? 0 : 1) + 0x21
42     c2 := (t2 < 0x5E ? t2 : t2-0x5E) + 0x21
43   Conversion (c1,c2) -> (s1,s2):
44     t := (c1 < 0x4A ? (c1-0x21+0x1B2) : (c1-0x21+0x197))
45     s1 := t >> 1
46     t2 := (t & 1) * 0x5E + (c2 - 0x21)
47     s2 := (t2 < 0x4E ? t2+0x31 : t2+0x43)
48 */
49
50static int
51johab_mbtowc (conv_t conv, ucs4_t *pwc, const unsigned char *s, int n)
52{
53  unsigned char c = *s;
54  if (c < 0x80) {
55    if (c == 0x5c)
56      *pwc = (ucs4_t) 0x20a9;
57    else
58      *pwc = (ucs4_t) c;
59    return 1;
60  } else if (c < 0xd8) {
61    return johab_hangul_mbtowc(conv,pwc,s,n);
62  } else {
63    unsigned char s1, s2;
64    s1 = c;
65    if ((s1 >= 0xd9 && s1 <= 0xde) || (s1 >= 0xe0 && s1 <= 0xf9)) {
66      if (n < 2)
67        return RET_TOOFEW(0);
68      s2 = s[1];
69      if ((s2 >= 0x31 && s2 <= 0x7e) || (s2 >= 0x91 && s2 <= 0xfe)) {
70        /* In KSC 5601, now KS X 1001, the region s1 = 0xDA, 0xA1 <= s2 <= 0xD3
71           contains the 51 Jamo (Hangul letters). But in the Johab encoding,
72           they have been moved to the Hangul section, see
73           johab_hangul_page31. */
74        if (!(s1 == 0xda && (s2 >= 0xa1 && s2 <= 0xd3))) {
75          unsigned char t1 = (s1 < 0xe0 ? 2*(s1-0xd9) : 2*s1-0x197);
76          unsigned char t2 = (s2 < 0x91 ? s2-0x31 : s2-0x43);
77          unsigned char buf[2];
78          buf[0] = t1 + (t2 < 0x5e ? 0 : 1) + 0x21;
79          buf[1] = (t2 < 0x5e ? t2 : t2-0x5e) + 0x21;
80          return ksc5601_mbtowc(conv,pwc,buf,2);
81        }
82      }
83    }
84    return RET_ILSEQ;
85  }
86}
87
88static int
89johab_wctomb (conv_t conv, unsigned char *r, ucs4_t wc, int n)
90{
91  unsigned char buf[2];
92  int ret;
93
94  /* Try ASCII variation. */
95  if (wc < 0x0080 && wc != 0x005c) {
96    *r = wc;
97    return 1;
98  }
99  if (wc == 0x20a9) {
100    *r = 0x5c;
101    return 1;
102  }
103
104  /* Try JOHAB Hangul table before KSC5601 table, because the KSC5601 table
105     contains some (2350 out of 11172) Hangul syllables (rows 0x30XX..0x48XX),
106     and we want the search to return the JOHAB Hangul table entry. */
107
108  /* Try JOHAB Hangul. */
109  ret = johab_hangul_wctomb(conv,buf,wc,2);
110  if (ret != RET_ILUNI) {
111    if (ret != 2) abort();
112    if (n < 2)
113      return RET_TOOSMALL;
114    r[0] = buf[0];
115    r[1] = buf[1];
116    return 2;
117  }
118
119  /* Try KSC5601, now KS X 1001. */
120  ret = ksc5601_wctomb(conv,buf,wc,2);
121  if (ret != RET_ILUNI) {
122    unsigned char c1, c2;
123    if (ret != 2) abort();
124    if (n < 2)
125      return RET_TOOSMALL;
126    c1 = buf[0];
127    c2 = buf[1];
128    if (((c1 >= 0x21 && c1 <= 0x2c) || (c1 >= 0x4a && c1 <= 0x7d))
129        && (c2 >= 0x21 && c2 <= 0x7e)) {
130      unsigned int t = (c1 < 0x4A ? (c1-0x21+0x1B2) : (c1-0x21+0x197));
131      unsigned char t2 = ((t & 1) ? 0x5e : 0) + (c2 - 0x21);
132      r[0] = t >> 1;
133      r[1] = (t2 < 0x4e ? t2+0x31 : t2+0x43);
134      return 2;
135    }
136  }
137
138  return RET_ILUNI;
139}
140