111 lines
1.7 KiB
C
111 lines
1.7 KiB
C
#include "charset.h"
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static int
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add_unicode(char **d, size_t *len, uint16_t u)
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{
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if (u < 0x80)
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{
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// 1 byte
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if (*len < 1) return 0;
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(*d)[0] = (char)u;
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++(*d), --(*len);
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return 1;
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}
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if (u < 0x800)
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{
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// 2 bytes
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if (*len < 2) return 0;
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(*d)[0] = 0xc0 | ((u >> 6) & 0x1f);
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(*d)[1] = 0x80 | (u & 0x3f);
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*d += 2, *len -= 2;
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return 1;
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}
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#if 0
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if (u < 0x10000)
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#endif
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{
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// 3 bytes
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if (*len < 3) return 0;
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(*d)[0] = 0xe0 | ((u >> 12) & 0xf);
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(*d)[1] = 0x80 | ((u >> 6) & 0x3f);
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(*d)[2] = 0x80 | (u & 0x3f);
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*d += 3, *len -= 3;
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return 1;
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}
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// 4 byte code point not supported.
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return 0;
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}
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static int
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is_utf_sequence(char *s)
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{
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size_t utf8_len, i;
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if ((*s & 0xe0) == 0xc0) // U+0080+ 110xxxxx
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utf8_len = 1;
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else if ((*s & 0xf0) == 0xe0) // U+0800+ 1110xxxx
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utf8_len = 2;
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else if ((*s & 0xf8) == 0xf0) // U+10000+ 11110xxx
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utf8_len = 3;
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else return 0;
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for (i = 1; i <= utf8_len; ++i)
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{
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// UTF-8 continuation character 10xxxxxx
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if ((s[i] & 0xc0) != 0x80)
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// Invalid UTF-8 sequence
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return 0;
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}
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return 1;
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}
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size_t
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xconv(char *src, char *dst, size_t dstlen)
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{
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size_t i, len = dstlen - 1;
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char *s, *d;
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int changed = 0;
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for (s = src, d = dst; *s && len > 0; ++s)
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{
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if (!(*s & 0x80))
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{
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*(d++) = *s;
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--len;
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continue;
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}
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if (!changed && is_utf_sequence(s))
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return 0;
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changed = 1;
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// Check for combined character.
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if ((*s & 0xf0) == 0xc0)
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{
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if (s[1])
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{
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icc_t *p = iso6937_combined[*s & 0xf];
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for (i = 0; p[i].c; ++i)
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if (p[i].c == (s[1] & 0xff))
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{
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add_unicode(&d, &len, p[i].u);
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break;
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}
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++s;
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}
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}
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else
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add_unicode(&d, &len, iso6937_map[*s & 0xff]);
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}
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if (!changed)
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return 0;
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*d = '\0';
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return dstlen - len - 1;
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}
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