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/* copyright (c) 2022 - 2023 grunfink et al. / MIT license */
#ifndef _XS_UNICODE_H
#define _XS_UNICODE_H
xs_str *xs_utf8_enc(xs_str *str, unsigned int cpoint);
char *xs_utf8_dec(const char *str, unsigned int *cpoint);
#ifdef XS_IMPLEMENTATION
char *_xs_utf8_enc(char buf[4], unsigned int cpoint)
/* encodes an Unicode codepoint to utf-8 into buf and returns the new position */
{
unsigned char *p = (unsigned char *)buf;
if (cpoint < 0x80) /* 1 byte char */
*p++ = cpoint & 0xff;
else {
if (cpoint < 0x800) /* 2 byte char */
*p++ = 0xc0 | (cpoint >> 6);
else {
if (cpoint < 0x10000) /* 3 byte char */
*p++ = 0xe0 | (cpoint >> 12);
else { /* 4 byte char */
*p++ = 0xf0 | (cpoint >> 18);
*p++ = 0x80 | ((cpoint >> 12) & 0x3f);
}
*p++ = 0x80 | ((cpoint >> 6) & 0x3f);
}
*p++ = 0x80 | (cpoint & 0x3f);
}
return (char *)p;
}
xs_str *xs_utf8_enc(xs_str *str, unsigned int cpoint)
/* encodes an Unicode codepoint to utf-8 into str */
{
char tmp[4], *p;
p = _xs_utf8_enc(tmp, cpoint);
return xs_append_m(str, tmp, p - tmp);
}
char *xs_utf8_dec(const char *str, unsigned int *cpoint)
/* decodes an utf-8 char inside str into cpoint and returns the next position */
{
unsigned char *p = (unsigned char *)str;
int c = *p++;
int cb = 0;
if ((c & 0x80) == 0) { /* 1 byte char */
*cpoint = c;
}
else
if ((c & 0xe0) == 0xc0) { /* 2 byte char */
*cpoint = (c & 0x1f) << 6;
cb = 1;
}
else
if ((c & 0xf0) == 0xe0) { /* 3 byte char */
*cpoint = (c & 0x0f) << 12;
cb = 2;
}
else
if ((c & 0xf8) == 0xf0) { /* 4 byte char */
*cpoint = (c & 0x07) << 18;
cb = 3;
}
/* process the continuation bytes */
while (cb--) {
if ((*p & 0xc0) == 0x80)
*cpoint |= (*p++ & 0x3f) << (cb * 6);
else {
*cpoint = 0xfffd;
break;
}
}
return (char *)p;
}
#endif /* XS_IMPLEMENTATION */
#endif /* _XS_UNICODE_H */
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