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#include "unicode.h"
uint8_t utf8_enc(utf32_t ch, utf8_t *str) {
if (ch <= 0x7f) {
str[0] = ch;
return 1;
} else if (ch <= 0x7ff) {
str[0] = 0xc0 | (ch >> 6);
str[1] = 0x80 | (ch & 0x3f);
return 2;
} else if (ch <= 0xffff) {
if ((ch >= 0xd800) && (ch <= 0xdfff)) return 0;
str[0] = 0xe0 | (ch >> 12);
str[1] = 0x80 | ((ch >> 6) & 0x3f);
str[2] = 0x80 | (ch & 0x3f);
return 3;
} else if (ch <= 0x10ffff) {
str[0] = 0xf0 | (ch >> 18);
str[1] = 0x80 | ((ch >> 12) & 0x3f);
str[2] = 0x80 | ((ch >> 6) & 0x3f);
str[3] = 0x80 | (ch & 0x3f);
return 4;
} else {
return 0;
}
}
uint8_t utf8_dec(utf8_t *str, utf32_t *ch) {
if ((str[0] & 0x80) == 0x00) {
*ch = str[0];
return 1;
} else if ((str[0] & 0xe0) == 0xc0) {
if ((str[1] & 0xc0) != 0x80) return 0;
*ch = (utf32_t)(str[0] & 0x1f) << 6;
*ch |= (utf32_t)(str[1] & 0x3f);
if (*ch < 0x80) return 0;
return 2;
} else if ((str[0] & 0xf0) == 0xe0) {
if (((str[1] & 0xc0) != 0x80) || ((str[2] & 0xc0) != 0x80)) return 0;
*ch = (utf32_t)(str[0] & 0x0f) << 12;
*ch |= (utf32_t)(str[1] & 0x3f) << 6;
*ch |= (utf32_t)(str[2] & 0x3f);
if ((*ch >= 0xd800) && (*ch <= 0xdfff)) return 0;
if (*ch < 0x800) return 0;
return 3;
} else if ((str[0] & 0xf8) == 0xf0) {
if (((str[1] & 0xc0) != 0x80) || ((str[2] & 0xc0) != 0x80) || ((str[3] & 0xc0) != 0x80)) return 0;
*ch = (utf32_t)(str[0] & 0x07) << 18;
*ch |= (utf32_t)(str[1] & 0x0f) << 12;
*ch |= (utf32_t)(str[2] & 0x3f) << 6;
*ch |= (utf32_t)(str[3] & 0x3f);
if (*ch < 0x010000) return 0;
if (*ch > 0x10ffff) return 0;
return 4;
} else {
return 0;
}
}
int utf8_seek(utf8_t *str, int off, utf32_t *ch) {
int i;
int len = 0;
if (off < 0) {
off = -off;
for (i=0; i<off; i++) {
len--;
while ((*(str + len) & 0xc0) == 0x80) len--;
}
utf8_dec(str + len, ch);
} else {
for (i=0; i<off; i++) {
len += utf8_dec(str + len, ch);
}
}
return len;
}
int utf8_verify(utf8_t *str, int sz) {
utf32_t ch;
uint8_t ch_l;
int len = 0;
while (len < sz) {
if (sz - len < 4) {
if (((str[len] & 0xf8) == 0xf0) ||
(((str[len] & 0xf0) == 0xe0) && (sz - len < 3)) ||
(((str[len] & 0xe0) == 0xc0) && (sz - len < 2))) {
str[len] = '\0';
break;
}
}
ch_l = utf8_dec(str + len, &ch);
if (ch_l) {
if (ch == 0) break;
len += ch_l;
} else {
str[len] = '\0';
break;
}
}
return len;
}
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