/*
 * Copyright (c) 2000 Yuki Sawada
 * All rights reserved.
 *
 * 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. The name of the author may not be used to endorse or promote products
 *    derived from this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``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 AUTHOR 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.
 */

#include "codeconv.h"
#include "codeconv_tbl.h"

unsigned int codeconv_euc_to_jis(unsigned int euc)
{
	unsigned int hi, low;

	hi = (euc >> 8) & 0xff;
	low = euc & 0xff;

	if (hi < 0x81) {
		hi = 0;
	} else if (low == 0x8e)
		hi = 0;
	else {
		hi -= 0x80;
		low -= 0x80;
	}

	return (hi << 8) | low;
}

static unsigned int codeconv_jis_to_unicode(unsigned int jis)
{
	int k0, k1;

	if (jis < 0x80) return jis; // ASCII

	k0 = (jis >> 8) - 0x20;

	if (k0 < 1 || k0 > 92)
		return 0;

	k1 = (jis % 0x100) - 0x20;
	if (k1 < 1 || k1 > 94)
		return 0;

	return unicode_tbl[k0 - 1][k1 - 1];
}

unsigned int codeconv_euc_to_unicode(unsigned int euc)
{
	unsigned int jis, unicode;

	jis = codeconv_euc_to_jis(euc);
	unicode = codeconv_jis_to_unicode(jis);

	return unicode;
}

static unsigned int codeconv_unicode_to_jis(unsigned int unicode)
{
	int k0, k1;
	unsigned int jis;

	k0 = (unicode >> 8) & 0xff;
	k1 = unicode & 0xff;
	jis = unicode_rev_table[k0][k1];

	return jis;
}

static unsigned int codeconv_jis_to_euc(unsigned int jis)
{
	unsigned int hi, low;

	hi = (jis >> 8) & 0x7f | 0x80;
	low = jis & 0x7f | 0x80;

	return (hi << 8) | low;
}

unsigned int codeconv_unicode_to_euc(unsigned int unicode)
{
	unsigned int jis, euc;

	if (unicode >= 0xff61 && unicode <= 0xff9f)
	return unicode - 0xff61 + 0x8ea1;

	jis = codeconv_unicode_to_jis(unicode);
	if (jis == 0)
		return 0x7878;
	euc = codeconv_jis_to_euc(jis);

	return euc;
}

static unsigned int codeconv_jis_to_sjis(unsigned int jis)
{
	unsigned int hi, low;

	hi = (jis >> 8) & 0xff;
	low = jis & 0xff;

	low += (hi & 0x01) ? 0x1f : 0x7d;
	if (low >= 0x7f)
		low++;
	hi = ((hi - 0x21) >> 1) + 0x81;
	if (hi > 0x9f)
		hi += 0x40;

	return (hi << 8) | low;
}

unsigned int codeconv_euc_to_sjis(unsigned int euc)
{
	unsigned int jis, sjis;

	jis = codeconv_euc_to_jis(euc);
	sjis = codeconv_jis_to_sjis(jis);

	return sjis;
}

static unsigned int codeconv_sjis_to_jis(unsigned int sjis)
{
	unsigned int hi, low;

	hi = (sjis >> 8) & 0xff;
	low = sjis & 0xff;

	hi -= (hi <= 0x9f) ? 0x71 : 0xb1;
	hi = (hi << 1) + 1;
	if (low > 0x7f)
		low--;
	if (low >= 0x9e) {
		low -= 0x7d;
		hi++;
	} else low -= 0x1f;

	return (hi << 8) | low;
}

unsigned int codeconv_sjis_to_euc(unsigned int sjis)
{
	unsigned int jis, euc;

	jis = codeconv_sjis_to_jis(sjis);
	euc = codeconv_jis_to_euc(jis);

	return euc;
}

unsigned int codeconv_euc_to_latin1(unsigned int euc)
{
	int high = (euc>>8) & 0xff;
	if (high) return 0;
	return euc & 0xff;
}