lib/unistr/u16-uctomb-aux.c

   1 /* Conversion UCS-4 to UTF-16.
   2    Copyright (C) 2002, 2006-2007, 2009-2021 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 Lesser 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    Lesser General Public License for more details.
  14
  15    You should have received a copy of the GNU Lesser General Public License
  16    along with this program.  If not, see <https://www.gnu.org/licenses/>.  */
  17
  18 #include <config.h>
  19
  20 /* Specification.  */
  21 #include "unistr.h"
  22
  23 int
  24 u16_uctomb_aux (uint16_t *s, ucs4_t uc, ptrdiff_t n)
  25 {
  26   if (uc < 0xd800)
  27     {
  28       /* The case n >= 1 is already handled by the caller.  */
  29     }
  30   else if (uc < 0x10000)
  31     {
  32       if (uc >= 0xe000)
  33         {
  34           if (n >= 1)
  35             {
  36               s[0] = uc;
  37               return 1;
  38             }
  39         }
  40       else
  41         return -1;
  42     }
  43   else
  44     {
  45       if (uc < 0x110000)
  46         {
  47           if (n >= 2)
  48             {
  49               s[0] = 0xd800 + ((uc - 0x10000) >> 10);
  50               s[1] = 0xdc00 + ((uc - 0x10000) & 0x3ff);
  51               return 2;
  52             }
  53         }
  54       else
  55         return -1;
  56     }
  57   return -2;
  58 }