1 /* 2 * This code was written by Rich Felker in 2010; no copyright is claimed. 3 * This code is in the public domain. Attribution is appreciated but 4 * unnecessary. 5 */ 6 7 #include <wchar.h> 8 #include <errno.h> 9 #include "internal.h" 10 11 int mbtowc(wchar_t *restrict wc, const char *restrict src, size_t n) 12 { 13 unsigned c; 14 const unsigned char *s = (const void *)src; 15 16 if (!s) return 0; 17 if (!n) goto ilseq; 18 if (!wc) wc = (void *)&wc; 19 20 if (*s < 0x80) return !!(*wc = *s); 21 if (*s-SA > SB-SA) goto ilseq; 22 c = bittab[*s++-SA]; 23 24 /* Avoid excessive checks against n: If shifting the state n-1 25 * times does not clear the high bit, then the value of n is 26 * insufficient to read a character */ 27 if (n<4 && ((c<<(6*n-6)) & (1U<<31))) goto ilseq; 28 29 if (OOB(c,*s)) goto ilseq; 30 c = c<<6 | *s++-0x80; 31 if (!(c&(1U<<31))) { 32 *wc = c; 33 return 2; 34 } 35 36 if (*s-0x80u >= 0x40) goto ilseq; 37 c = c<<6 | *s++-0x80; 38 if (!(c&(1U<<31))) { 39 *wc = c; 40 return 3; 41 } 42 43 if (*s-0x80u >= 0x40) goto ilseq; 44 *wc = c<<6 | *s++-0x80; 45 return 4; 46 47 ilseq: 48 errno = EILSEQ; 49 return -1; 50 } 51
