1/*
2 * Copyright (C) 1999-2001 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, size_t 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, the region s1 = 0xDA, 0xA1 <= s2 <= 0xD3 contains
71           the 51 Jamo (Hangul letters). But in the Johab encoding, they
72           have been moved to the Hangul section, see johab_hangul_page31. */
73        if (!(s1 == 0xda && (s2 >= 0xa1 && s2 <= 0xd3))) {
74          unsigned char t1 = (s1 < 0xe0 ? 2*(s1-0xd9) : 2*s1-0x197);
75          unsigned char t2 = (s2 < 0x91 ? s2-0x31 : s2-0x43);
76          unsigned char buf[2];
77          buf[0] = t1 + (t2 < 0x5e ? 0 : 1) + 0x21;
78          buf[1] = (t2 < 0x5e ? t2 : t2-0x5e) + 0x21;
79          return ksc5601_mbtowc(conv,pwc,buf,2);
80        }
81      }
82    }
83    return RET_ILSEQ;
84  }
85}
86
87static int
88johab_wctomb (conv_t conv, unsigned char *r, ucs4_t wc, size_t n)
89{
90  unsigned char buf[2];
91  int ret;
92
93  /* Try ASCII variation. */
94  if (wc < 0x0080 && wc != 0x005c) {
95    *r = wc;
96    return 1;
97  }
98  if (wc == 0x20a9) {
99    *r = 0x5c;
100    return 1;
101  }
102
103  /* Try JOHAB Hangul table before KSC5601 table, because the KSC5601 table
104     contains some (2350 out of 11172) Hangul syllables (rows 0x30XX..0x48XX),
105     and we want the search to return the JOHAB Hangul table entry. */
106
107  /* Try JOHAB Hangul. */
108  ret = johab_hangul_wctomb(conv,buf,wc,2);
109  if (ret != RET_ILUNI) {
110    if (ret != 2) abort();
111    if (n < 2)
112      return RET_TOOSMALL;
113    r[0] = buf[0];
114    r[1] = buf[1];
115    return 2;
116  }
117
118  /* Try KSC5601. */
119  ret = ksc5601_wctomb(conv,buf,wc,2);
120  if (ret != RET_ILUNI) {
121    unsigned char c1, c2;
122    if (ret != 2) abort();
123    if (n < 2)
124      return RET_TOOSMALL;
125    c1 = buf[0];
126    c2 = buf[1];
127    if (((c1 >= 0x21 && c1 <= 0x2c) || (c1 >= 0x4a && c1 <= 0x7d))
128        && (c2 >= 0x21 && c2 <= 0x7e)) {
129      unsigned int t = (c1 < 0x4A ? (c1-0x21+0x1B2) : (c1-0x21+0x197));
130      unsigned char t2 = ((t & 1) ? 0x5e : 0) + (c2 - 0x21);
131      r[0] = t >> 1;
132      r[1] = (t2 < 0x4e ? t2+0x31 : t2+0x43);
133      return 2;
134    }
135  }
136
137  return RET_ILUNI;
138}
139