blob: 7599377b4ed36e2188b6611c2c6e3b48c7a5acd0 (
plain) (
blame)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
|
#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.
// Overlong sequences, surrogates and 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 < 0xc0) { return -1; }
if (*s < 0xe0) { *cp = *s & 0x1f; goto u2; }
if (*s < 0xf0) { *cp = *s & 0x0f; goto u3; }
if (*s < 0xf8) { *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;
}
|