/* Test for initial conversion state.

   Copyright (C) 2008-2018 Free Software Foundation, Inc.

   Written by Bruno Haible <bruno@clisp.org>, 2008.

   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 3 of the License, 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, see <https://www.gnu.org/licenses/>.  */

#include <config.h>

/* Specification.  */

#include <wchar.h>

#include "verify.h"

#if GNULIB_defined_mbstate_t

/* Platforms that lack mbsinit() also lack mbrlen(), mbrtowc(), mbsrtowcs()

   and wcrtomb(), wcsrtombs().

   We assume that

     - sizeof (mbstate_t) >= 4,

     - only stateless encodings are supported (such as UTF-8 and EUC-JP, but

       not ISO-2022 variants),

     - for each encoding, the number of bytes for a wide character is <= 4.

       (This maximum is attained for UTF-8, GB18030, EUC-TW.)

   We define the meaning of mbstate_t as follows:

     - In mb -> wc direction, mbstate_t's first byte contains the number of

       buffered bytes (in the range 0..3), followed by up to 3 buffered bytes.

       See mbrtowc.c.

     - In wc -> mb direction, mbstate_t contains no information. In other

       words, it is always in the initial state.  */

verify (sizeof (mbstate_t) >= 4);

int

mbsinit (const mbstate_t *ps)

{

  const char *pstate = (const char *)ps;

  return pstate == NULL || pstate[0] == 0;

}

#else

int

mbsinit (const mbstate_t *ps)

{

# if defined _WIN32 && !defined __CYGWIN__

  /* Native Windows.  */

#  ifdef __MINGW32__

  /* On mingw, 'mbstate_t' is defined as 'int'.  */

  return ps == NULL || *ps == 0;

#  else

  /* MSVC defines 'mbstate_t' as an 8-byte struct; the first 4-bytes matter.  */

  return ps == NULL || *(const unsigned int *)ps == 0;

#  endif

# else

  /* Minix, HP-UX 11.00, Solaris 2.6, Interix, ...  */

  /* Maybe this definition works, maybe not...  */

  return ps == NULL || *(const char *)ps == 0;

# endif

}

#endif