/* Conversion UTF-8 to UCS-4.

   Copyright (C) 2001-2002, 2006-2007, 2009-2019 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 either:

     * 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.

   or

     * the GNU General Public License as published by the Free

       Software Foundation; either version 2 of the License, or (at your

       option) any later version.

   or both in parallel, as here.

   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 <https://www.gnu.org/licenses/>.  */

#include <config.h>

/* Specification.  */

#include "unistr.h"

#if defined IN_LIBUNISTRING || HAVE_INLINE

int

u8_mbtouc_unsafe_aux (ucs4_t *puc, const uint8_t *s, size_t n)

{

  uint8_t c = *s;

  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 1;

            }

        }

      else if (c < 0xf0)

        {

          if (n >= 3)

            {

              if ((s[1] ^ 0x80) < 0x40)

                {

                  if ((s[2] ^ 0x80) < 0x40)

                    {

                      if ((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 */

                      *puc = 0xfffd;

                      return 3;

                    }

                  /* invalid multibyte character */

                  *puc = 0xfffd;

                  return 2;

                }

              /* invalid multibyte character */

            }

          else

            {

              /* incomplete multibyte character */

              *puc = 0xfffd;

              if (n == 1 || (s[1] ^ 0x80) >= 0x40)

                return 1;

              else

                return 2;

            }

        }

      else if (c < 0xf8)

        {

          if (n >= 4)

            {

              if ((s[1] ^ 0x80) < 0x40)

                {

                  if ((s[2] ^ 0x80) < 0x40)

                    {

                      if ((s[3] ^ 0x80) < 0x40)

                        {

                          if ((c >= 0xf1 || s[1] >= 0x90)

                              && (c < 0xf4 || (c == 0xf4 && s[1] < 0x90))

                             )

                            {

                              *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 */

                          *puc = 0xfffd;

                          return 4;

                        }

                      /* invalid multibyte character */

                      *puc = 0xfffd;

                      return 3;

                    }

                  /* invalid multibyte character */

                  *puc = 0xfffd;

                  return 2;

                }

              /* invalid multibyte character */

            }

          else

            {

              /* incomplete multibyte character */

              *puc = 0xfffd;

              if (n == 1 || (s[1] ^ 0x80) >= 0x40)

                return 1;

              else if (n == 2 || (s[2] ^ 0x80) >= 0x40)

                return 2;

              else

                return 3;

            }

        }

    }

  /* invalid multibyte character */

  *puc = 0xfffd;

  return 1;

}

#endif