/* Look at first character in UTF-8 string.
   Copyright (C) 1999-2002, 2006-2007, 2009-2010 Free Software Foundation, Inc.
   Written by Bruno Haible <bruno@clisp.org>, 2001.

   This program is free software: you can redistribute it and/or modify it
   under the terms of the GNU Lesser General Public License as published
   by the Free Software Foundation; either version 3 of the License, or
   (at your option) any later version.

   This program is distributed in the hope that it will be useful,
   but WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
   Lesser General Public License for more details.

   You should have received a copy of the GNU Lesser General Public License
   along with this program.  If not, see <http://www.gnu.org/licenses/>.  */

#include <config.h>

#if defined IN_LIBUNISTRING
/* Tell unistr.h to declare u8_mbtouc as 'extern', not 'static inline'.  */
# include "unistring-notinline.h"
#endif

/* Specification.  */
#include "unistr.h"

#if !HAVE_INLINE

int
u8_mbtouc (ucs4_t *puc, const uint8_t *s, size_t n)
{
  uint8_t c = *s;

  if (c < 0x80)
    {
      *puc = c;
      return 1;
    }
  else if (c >= 0xc2)
    {
      if (c < 0xe0)
        {
          if (n >= 2)
            {
              if ((s[1] ^ 0x80) < 0x40)
                {
                  *puc = ((unsigned int) (c & 0x1f) << 6)
                         | (unsigned int) (s[1] ^ 0x80);
                  return 2;
                }
              /* invalid multibyte character */
            }
          else
            {
              /* incomplete multibyte character */
              *puc = 0xfffd;
              return n;
            }
        }
      else if (c < 0xf0)
        {
          if (n >= 3)
            {
              if ((s[1] ^ 0x80) < 0x40 && (s[2] ^ 0x80) < 0x40
                  && (c >= 0xe1 || s[1] >= 0xa0)
                  && (c != 0xed || s[1] < 0xa0))
                {
                  *puc = ((unsigned int) (c & 0x0f) << 12)
                         | ((unsigned int) (s[1] ^ 0x80) << 6)
                         | (unsigned int) (s[2] ^ 0x80);
                  return 3;
                }
              /* invalid multibyte character */
            }
          else
            {
              /* incomplete multibyte character */
              *puc = 0xfffd;
              return n;
            }
        }
      else if (c < 0xf8)
        {
          if (n >= 4)
            {
              if ((s[1] ^ 0x80) < 0x40 && (s[2] ^ 0x80) < 0x40
                  && (s[3] ^ 0x80) < 0x40
                  && (c >= 0xf1 || s[1] >= 0x90)
#if 1
                  && (c < 0xf4 || (c == 0xf4 && s[1] < 0x90))
#endif
                 )
                {
                  *puc = ((unsigned int) (c & 0x07) << 18)
                         | ((unsigned int) (s[1] ^ 0x80) << 12)
                         | ((unsigned int) (s[2] ^ 0x80) << 6)
                         | (unsigned int) (s[3] ^ 0x80);
                  return 4;
                }
              /* invalid multibyte character */
            }
          else
            {
              /* incomplete multibyte character */
              *puc = 0xfffd;
              return n;
            }
        }
#if 0
      else if (c < 0xfc)
        {
          if (n >= 5)
            {
              if ((s[1] ^ 0x80) < 0x40 && (s[2] ^ 0x80) < 0x40
                  && (s[3] ^ 0x80) < 0x40 && (s[4] ^ 0x80) < 0x40
                  && (c >= 0xf9 || s[1] >= 0x88))
                {
                  *puc = ((unsigned int) (c & 0x03) << 24)
                         | ((unsigned int) (s[1] ^ 0x80) << 18)
                         | ((unsigned int) (s[2] ^ 0x80) << 12)
                         | ((unsigned int) (s[3] ^ 0x80) << 6)
                         | (unsigned int) (s[4] ^ 0x80);
                  return 5;
                }
              /* invalid multibyte character */
            }
          else
            {
              /* incomplete multibyte character */
              *puc = 0xfffd;
              return n;
            }
        }
      else if (c < 0xfe)
        {
          if (n >= 6)
            {
              if ((s[1] ^ 0x80) < 0x40 && (s[2] ^ 0x80) < 0x40
                  && (s[3] ^ 0x80) < 0x40 && (s[4] ^ 0x80) < 0x40
                  && (s[5] ^ 0x80) < 0x40
                  && (c >= 0xfd || s[1] >= 0x84))
                {
                  *puc = ((unsigned int) (c & 0x01) << 30)
                         | ((unsigned int) (s[1] ^ 0x80) << 24)
                         | ((unsigned int) (s[2] ^ 0x80) << 18)
                         | ((unsigned int) (s[3] ^ 0x80) << 12)
                         | ((unsigned int) (s[4] ^ 0x80) << 6)
                         | (unsigned int) (s[5] ^ 0x80);
                  return 6;
                }
              /* invalid multibyte character */
            }
          else
            {
              /* incomplete multibyte character */
              *puc = 0xfffd;
              return n;
            }
        }
#endif
    }
  /* invalid multibyte character */
  *puc = 0xfffd;
  return 1;
}

#endif
