/* Conversion UCS-4 to UTF-8.
   Copyright (C) 2002 Free Software Foundation, Inc.
   Written by Bruno Haible <haible@clisp.cons.org>, 2002.

This program is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 2, 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 General Public License for more details.

You should have received a copy of the GNU General Public License
along with this program; if not, write to the Free Software Foundation,
Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.  */


#include <stddef.h>

/* Return the length (number of units) of the UTF-8 representation of uc,
   after storing it at S.  Return -1 upon failure, -2 if the number of
   available units, N, is too small.  */
static int
u8_uctomb_aux (unsigned char *s, unsigned int uc, int n)
{
  int count;

  if (uc < 0x80)
    count = 1;
  else if (uc < 0x800)
    count = 2;
  else if (uc < 0x10000)
    count = 3;
#if 0
  else if (uc < 0x200000)
    count = 4;
  else if (uc < 0x4000000)
    count = 5;
  else if (uc <= 0x7fffffff)
    count = 6;
#else
  else if (uc < 0x110000)
    count = 4;
#endif
  else
    return -1;

  if (n < count)
    return -2;

  switch (count) /* note: code falls through cases! */
    {
#if 0
    case 6: s[5] = 0x80 | (uc & 0x3f); uc = uc >> 6; uc |= 0x4000000;
    case 5: s[4] = 0x80 | (uc & 0x3f); uc = uc >> 6; uc |= 0x200000;
#endif
    case 4: s[3] = 0x80 | (uc & 0x3f); uc = uc >> 6; uc |= 0x10000;
    case 3: s[2] = 0x80 | (uc & 0x3f); uc = uc >> 6; uc |= 0x800;
    case 2: s[1] = 0x80 | (uc & 0x3f); uc = uc >> 6; uc |= 0xc0;
    case 1: s[0] = uc;
    }
  return count;
}

static inline int
u8_uctomb (unsigned char *s, unsigned int uc, int n)
{
  if (uc < 0x80 && n > 0)
    {
      s[0] = uc;
      return 1;
    }
  else
    return u8_uctomb_aux (s, uc, n);
}