gl/unistr/u8-uctomb-aux.c

   1 /* Conversion UCS-4 to UTF-8.
   2    Copyright (C) 2002, 2006-2007, 2009-2012 Free Software Foundation, Inc.
   3    Written by Bruno Haible <bruno@clisp.org>, 2002.
   4
   5    This program is free software: you can redistribute it and/or modify it
   6    under the terms of the GNU General Public License as published
   7    by the Free Software Foundation; either version 3 of the License, or
   8    (at your option) any later version.
   9
  10    This program is distributed in the hope that it will be useful,
  11    but WITHOUT ANY WARRANTY; without even the implied warranty of
  12    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  13    General Public License for more details.
  14
  15    You should have received a copy of the GNU General Public License
  16    along with this program.  If not, see <http://www.gnu.org/licenses/>.  */
  17
  18 #include <config.h>
  19
  20 /* Specification.  */
  21 #include "unistr.h"
  22
  23 int
  24 u8_uctomb_aux (uint8_t *s, ucs4_t uc, int n)
  25 {
  26   int count;
  27
  28   if (uc < 0x80)
  29     /* The case n >= 1 is already handled by the caller.  */
  30     return -2;
  31   else if (uc < 0x800)
  32     count = 2;
  33   else if (uc < 0x10000)
  34     {
  35       if (uc < 0xd800 || uc >= 0xe000)
  36         count = 3;
  37       else
  38         return -1;
  39     }
  40 #if 0
  41   else if (uc < 0x200000)
  42     count = 4;
  43   else if (uc < 0x4000000)
  44     count = 5;
  45   else if (uc <= 0x7fffffff)
  46     count = 6;
  47 #else
  48   else if (uc < 0x110000)
  49     count = 4;
  50 #endif
  51   else
  52     return -1;
  53
  54   if (n < count)
  55     return -2;
  56
  57   switch (count) /* note: code falls through cases! */
  58     {
  59 #if 0
  60     case 6: s[5] = 0x80 | (uc & 0x3f); uc = uc >> 6; uc |= 0x4000000;
  61     case 5: s[4] = 0x80 | (uc & 0x3f); uc = uc >> 6; uc |= 0x200000;
  62 #endif
  63     case 4: s[3] = 0x80 | (uc & 0x3f); uc = uc >> 6; uc |= 0x10000;
  64     case 3: s[2] = 0x80 | (uc & 0x3f); uc = uc >> 6; uc |= 0x800;
  65     case 2: s[1] = 0x80 | (uc & 0x3f); uc = uc >> 6; uc |= 0xc0;
  66   /*case 1:*/ s[0] = uc;
  67     }
  68   return count;
  69 }