/*
 * char-sjis.h
 *
 *   Copyright (c) 2000-2007  Shiro Kawai  <shiro@acm.org>
 * 
 *   Redistribution and use in source and binary forms, with or without
 *   modification, are permitted provided that the following conditions
 *   are met:
 * 
 *   1. Redistributions of source code must retain the above copyright
 *      notice, this list of conditions and the following disclaimer.
 *
 *   2. Redistributions in binary form must reproduce the above copyright
 *      notice, this list of conditions and the following disclaimer in the
 *      documentation and/or other materials provided with the distribution.
 *
 *   3. Neither the name of the authors nor the names of its contributors
 *      may be used to endorse or promote products derived from this
 *      software without specific prior written permission.
 *
 *   THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
 *   "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
 *   LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
 *   A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
 *   OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
 *   SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED
 *   TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
 *   PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
 *   LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
 *   NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
 *   SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 *
 *  $Id: char_sjis.h,v 1.7 2007/03/22 11:20:30 shirok Exp $
 */

#ifndef SCM_CHAR_ENCODING_BODY
/*===============================================================
 * Header part
 */

/* The name of the encoding.  Scheme procedure 
 * gauche-character-encoding returns a symbol with this name.
 */
#define SCM_CHAR_ENCODING_NAME "sjis"

/* Given first byte of the multibyte character, returns # of
 * bytes that follows, i.e. if the byte consists a single-byte
 * character, it returns 0; if the byte is the first byte of
 * two-byte character, it returns 1.   It may return -1 if
 * the given byte can't be a valid first byte of multibyte characters.
 */
#define SCM_CHAR_NFOLLOWS(byte)                   \
    (((unsigned char)(byte)) < 0x81? 0 :          \
     (((unsigned char)(byte)) < 0xa0? 1 :         \
      (((unsigned char)(byte)) < 0xe0? 0 : 1)))

/* Given wide character CH, returns # of bytes used when CH is
 * encoded in multibyte string.
 */
#define SCM_CHAR_NBYTES(ch) (((ch) > 0x0ff) ? 2 : 1)

/* Maximun # of multibyte character */
#define SCM_CHAR_MAX_BYTES     2

/* From a multibyte string pointed by const char *cp, extract a character
 * and store it in ScmChar ch.  If cp doesn't point to valid multibyte
 * character, store SCM_CHAR_INVALID to ch.  cp is not modified.
 */
#define SCM_CHAR_GET(cp, ch)                                                \
    do {                                                                    \
        (ch) = (unsigned char)*(cp);                                        \
        if ((unsigned char)(ch) >= 0x80) {                                  \
          if ((unsigned char)(ch) < 0xa0 || (unsigned char)(ch) >= 0xe0) {  \
             (ch) = (((unsigned char)(ch)) << 8) + (unsigned char)*(cp+1);  \
          }                                                                 \
        }                                                                   \
    } while (0)

/* Convert a character CH to multibyte form and put it to the buffer
 * starting from char *cp.  You can assume the buffer has enough length
 * to contain the multibyte char.   cp is not modified.
 */
#define SCM_CHAR_PUT(cp, ch)                    \
    do {                                        \
        if ((ch) > 0xff) {                      \
            (cp)[0] = (ch >> 8) & 0xff;         \
            (cp)[1] = ch & 0xff;                \
        } else {                                \
            (cp)[0] = ch & 0xff;                \
        }                                       \
    } while (0)

/* const char *cp points to a multibyte string.  Set const char *result
 * to point to the previous character of the one cp points to.
 * const char *start points to the beginning of the buffer.
 * result is set to NULL if there's no valid multibyte char found
 * just before cp.   cp and start is not modified.
 */
#define SCM_CHAR_BACKWARD(cp, start, result)                    \
    do {                                                        \
        (result) = (cp);                                        \
        if ((result) == (start)) (result) = NULL;               \
        else if ((result) == (start) + 1) (result) = (start);   \
        else if (SCM_CHAR_NFOLLOWS(*((result)-2)) == 1) {       \
             (result) -= 2;                                     \
        } else {                                                \
             (result) -= 1;                                     \
        }                                                       \
    } while (0)

#else  /* !SCM_CHAR_ENCODING_BODY */
/*==================================================================
 * This part is included in char.c
 */

/* Array of character encoding names, recognizable by iconv, that are
   compatible with this native encoding. */
static const char *supportedCharacterEncodings[] = {
    "SHIFT_JIS",
    "SHIFT-JIS",
    "SHIFT_JISX0213",
    "SHIFT-JISX0213",
    "SJIS",
    NULL
};

#endif /* !SCM_CHAR_ENCODING_BODY */
