/*-*- mode:c;indent-tabs-mode:nil;c-basic-offset:2;tab-width:8;coding:utf-8 -*-â
âvi: set net ft=c ts=2 sts=2 sw=2 fenc=utf-8                                :viâ
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â                                                                              â
â  Musl Libc                                                                   â
â  Copyright Â© 2005-2014 Rich Felker, et al.                                   â
â                                                                              â
â  Permission is hereby granted, free of charge, to any person obtaining       â
â  a copy of this software and associated documentation files (the             â
â  "Software"), to deal in the Software without restriction, including         â
â  without limitation the rights to use, copy, modify, merge, publish,         â
â  distribute, sublicense, and/or sell copies of the Software, and to          â
â  permit persons to whom the Software is furnished to do so, subject to       â
â  the following conditions:                                                   â
â                                                                              â
â  The above copyright notice and this permission notice shall be              â
â  included in all copies or substantial portions of the Software.             â
â                                                                              â
â  THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,             â
â  EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF          â
â  MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.      â
â  IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY        â
â  CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,        â
â  TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE           â
â  SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.                      â
â                                                                              â
ââââââââââââââââââââââââââââââââââââââââââââââââââââââââââââââââââââââââââââââ*/
#include "libc/errno.h"
#include "libc/limits.h"
#include "libc/str/mb.internal.h"
#include "libc/str/str.h"

asm(".ident\t\"\\n\\n\
Musl libc (MIT License)\\n\
Copyright 2005-2014 Rich Felker, et. al.\"");
asm(".include \"libc/disclaimer.inc\"");

int mbtowc(wchar_t *restrict wc, const char *restrict src, size_t n) {
  unsigned c;
  const unsigned char *s = (const void *)src;
  wchar_t dummy;
  if (!s) return 0;
  if (!n) goto ilseq;
  if (!wc) wc = &dummy;
  if (*s < 0x80) return !!(*wc = *s);
  if (MB_CUR_MAX == 1) return (*wc = CODEUNIT(*s)), 1;
  if (*s - SA > SB - SA) goto ilseq;
  c = kMbBittab[*s++ - SA];
  /* Avoid excessive checks against n: If shifting the state n-1
   * times does not clear the high bit, then the value of n is
   * insufficient to read a character */
  if (n < 4 && ((c << (6 * n - 6)) & (1U << 31))) goto ilseq;
  if (OOB(c, *s)) goto ilseq;
  c = c << 6 | *s++ - 0x80;
  if (!(c & (1U << 31))) {
    *wc = c;
    return 2;
  }
  if (*s - 0x80u >= 0x40) goto ilseq;
  c = c << 6 | *s++ - 0x80;
  if (!(c & (1U << 31))) {
    *wc = c;
    return 3;
  }
  if (*s - 0x80u >= 0x40) goto ilseq;
  *wc = c << 6 | *s++ - 0x80;
  return 4;
ilseq:
  errno = EILSEQ;
  return -1;
}
