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      1 /* Test for initial conversion state.
      2    Copyright (C) 2008 Free Software Foundation, Inc.
      3    Written by Bruno Haible <bruno (at) clisp.org>, 2008.
      4 
      5    This program is free software: you can redistribute it and/or modify
      6    it under the terms of the GNU General Public License as published by
      7    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
     13    GNU 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 <wchar.h>
     22 
     23 #include "verify.h"
     24 
     25 /* Platforms that lack mbsinit() also lack mbrlen(), mbrtowc(), mbsrtowcs()
     26    and wcrtomb(), wcsrtombs().
     27    We assume that
     28      - sizeof (mbstate_t) >= 4,
     29      - only stateless encodings are supported (such as UTF-8 and EUC-JP, but
     30        not ISO-2022 variants),
     31      - for each encoding, the number of bytes for a wide character is <= 4.
     32        (This maximum is attained for UTF-8, GB18030, EUC-TW.)
     33    We define the meaning of mbstate_t as follows:
     34      - In mb -> wc direction, mbstate_t's first byte contains the number of
     35        buffered bytes (in the range 0..3), followed by up to 3 buffered bytes.
     36      - In wc -> mb direction, mbstate_t contains no information. In other
     37        words, it is always in the initial state.  */
     38 
     39 verify (sizeof (mbstate_t) >= 4);
     40 
     41 int
     42 mbsinit (const mbstate_t *ps)
     43 {
     44   const char *pstate = (const char *)ps;
     45 
     46   return pstate[0] == 0;
     47 }
     48