1#include <stdlib.h>
 2#include <wchar.h>
 3#include <errno.h>
 4#include "internal.h"
 5
 6size_t mbrtowc(wchar_t *restrict wc, const char *restrict src, size_t n, mbstate_t *restrict st)
 7{
 8	static unsigned internal_state;
 9	unsigned c;
10	const unsigned char *s = (const void *)src;
11	const size_t N = n;
12	wchar_t dummy;
13
14	if (!st) st = (void *)&internal_state;
15	c = *(unsigned *)st;
16	
17	if (!s) {
18		if (c) goto ilseq;
19		return 0;
20	} else if (!wc) wc = &dummy;
21
22	if (!n) return -2;
23	if (!c) {
24		if (*s < 0x80) return !!(*wc = *s);
25		if (MB_CUR_MAX==1) return (*wc = CODEUNIT(*s)), 1;
26		if (*s-SA > SB-SA) goto ilseq;
27		c = bittab[*s++-SA]; n--;
28	}
29
30	if (n) {
31		if (OOB(c,*s)) goto ilseq;
32loop:
33		c = c<<6 | *s++-0x80; n--;
34		if (!(c&(1U<<31))) {
35			*(unsigned *)st = 0;
36			*wc = c;
37			return N-n;
38		}
39		if (n) {
40			if (*s-0x80u >= 0x40) goto ilseq;
41			goto loop;
42		}
43	}
44
45	*(unsigned *)st = c;
46	return -2;
47ilseq:
48	*(unsigned *)st = 0;
49	errno = EILSEQ;
50	return -1;
51}