src/multibyte/mbrtowc.c

   1 #include <stdlib.h>
   2 #include <wchar.h>
   3 #include <errno.h>
   4 #include "internal.h"
   5
   6 size_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;
  32 loop:
  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;
  47 ilseq:
  48         *(unsigned *)st = 0;
  49         errno = EILSEQ;
  50         return -1;
  51 }