personal fork of mblaze
選択できるのは25トピックまでです。 トピックは、先頭が英数字で、英数字とダッシュ('-')を使用した35文字以内のものにしてください。
 
 
 
 
 
 

33 行
1.1 KiB

#include <stdint.h>
// Decode one UTF-8 codepoint into cp, return number of bytes to next one.
// On invalid UTF-8, return -1, and do not change cp.
// Invalid codepoints are not checked.
//
// This code is meant to be inlined, if cp is unused it can be optimized away.
static int
u8decode(const char *cs, uint32_t *cp)
{
const uint8_t *s = (uint8_t *)cs;
if (*s == 0) { *cp = 0; return 0; }
if (*s < 0x80) { *cp = *s; return 1; }
if (*s < 0xc2) { return -1; } //cont+overlong
if (*s < 0xe0) { *cp = *s & 0x1f; goto u2; }
if (*s < 0xf0) {
if (*s == 0xe0 && (s[1] & 0xe0) == 0x80) return -1; //overlong
if (*s == 0xed && (s[1] & 0xe0) == 0xa0) return -1; //surrogate
*cp = *s & 0x0f; goto u3;
}
if (*s < 0xf5) {
if (*s == 0xf0 && (s[1] & 0xf0) == 0x80) return -1; //overlong
if (*s == 0xf4 && (s[1] > 0x8f)) return -1; //too high
*cp = *s & 0x07; goto u4;
}
return -1;
u4: if ((*++s & 0xc0) != 0x80) return -1; *cp = (*cp << 6) | (*s & 0x3f);
u3: if ((*++s & 0xc0) != 0x80) return -1; *cp = (*cp << 6) | (*s & 0x3f);
u2: if ((*++s & 0xc0) != 0x80) return -1; *cp = (*cp << 6) | (*s & 0x3f);
return s - (uint8_t *)cs + 1;
}