/*	$NetBSD: citrus_euc.c,v 1.14 2009/01/11 02:46:24 christos Exp $	*/

/*-
 * Copyright (c)2002 Citrus Project,
 * 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.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR 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 AUTHOR 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.
 */

/*-
 * SPDX-License-Identifier: BSD-3-Clause
 *
 * Copyright (c) 1993
 *	The Regents of the University of California.  All rights reserved.
 *
 * This code is derived from software contributed to Berkeley by
 * Paul Borman at Krystal Technologies.
 *
 * 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 University 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 REGENTS 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 REGENTS 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.
 */

#include <sys/types.h>

#include <assert.h>
#include <errno.h>
#include <limits.h>
#include <stddef.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <wchar.h>

#include "citrus_namespace.h"
#include "citrus_bcs.h"
#include "citrus_types.h"
#include "citrus_module.h"
#include "citrus_stdenc.h"
#include "citrus_euc.h"


/* ----------------------------------------------------------------------
 * private stuffs used by templates
 */

typedef struct {
	int	 chlen;
	char	 ch[3];
} _EUCState;

typedef struct {
	wchar_t		 bits[4];
	wchar_t		 mask;
	unsigned	 count[4];
	unsigned	 mb_cur_max;
} _EUCEncodingInfo;

#define	_SS2	0x008e
#define	_SS3	0x008f

#define _CEI_TO_EI(_cei_)		(&(_cei_)->ei)
#define _CEI_TO_STATE(_cei_, _func_)	(_cei_)->states.s_##_func_

#define _FUNCNAME(m)			_citrus_EUC_##m
#define _ENCODING_INFO			_EUCEncodingInfo
#define _ENCODING_STATE			_EUCState
#define _ENCODING_MB_CUR_MAX(_ei_)	(_ei_)->mb_cur_max
#define _ENCODING_IS_STATE_DEPENDENT	0
#define _STATE_NEEDS_EXPLICIT_INIT(_ps_)	0


static __inline int
_citrus_EUC_cs(unsigned int c)
{

	c &= 0xff;

	return ((c & 0x80) ? c == _SS3 ? 3 : c == _SS2 ? 2 : 1 : 0);
}

static __inline int
_citrus_EUC_parse_variable(_EUCEncodingInfo *ei, const void *var,
    size_t lenvar __unused)
{
	char *e;
	const char *v;
	int x;

	/* parse variable string */
	if (!var)
		return (EFTYPE);

	v = (const char *)var;

	while (*v == ' ' || *v == '\t')
		++v;

	ei->mb_cur_max = 1;
	for (x = 0; x < 4; ++x) {
		ei->count[x] = (int)_bcs_strtol(v, (char **)&e, 0);
		if (v == e || !(v = e) || ei->count[x] < 1 || ei->count[x] > 4) {
			return (EFTYPE);
		}
		if (ei->mb_cur_max < ei->count[x])
			ei->mb_cur_max = ei->count[x];
		while (*v == ' ' || *v == '\t')
			++v;
		ei->bits[x] = (int)_bcs_strtol(v, (char **)&e, 0);
		if (v == e || !(v = e)) {
			return (EFTYPE);
		}
		while (*v == ' ' || *v == '\t')
			++v;
	}
	ei->mask = (int)_bcs_strtol(v, (char **)&e, 0);
	if (v == e || !(v = e)) {
		return (EFTYPE);
	}

	return (0);
}


static __inline void
/*ARGSUSED*/
_citrus_EUC_init_state(_EUCEncodingInfo *ei __unused, _EUCState *s)
{

	memset(s, 0, sizeof(*s));
}

#if 0
static __inline void
/*ARGSUSED*/
_citrus_EUC_pack_state(_EUCEncodingInfo *ei __unused, void *pspriv,
    const _EUCState *s)
{

	memcpy(pspriv, (const void *)s, sizeof(*s));
}

static __inline void
/*ARGSUSED*/
_citrus_EUC_unpack_state(_EUCEncodingInfo *ei __unused, _EUCState *s,
    const void *pspriv)
{

	memcpy((void *)s, pspriv, sizeof(*s));
}
#endif

static int
_citrus_EUC_mbrtowc_priv(_EUCEncodingInfo *ei, wchar_t *pwc, char **s,
    size_t n, _EUCState *psenc, size_t *nresult)
{
	wchar_t wchar;
	int c, chlenbak, cs, len;
	char *s0, *s1 = NULL;

	s0 = *s;

	if (s0 == NULL) {
		_citrus_EUC_init_state(ei, psenc);
		*nresult = 0; /* state independent */
		return (0);
	}

	chlenbak = psenc->chlen;

	/* make sure we have the first byte in the buffer */
	switch (psenc->chlen) {
	case 0:
		if (n < 1)
			goto restart;
		psenc->ch[0] = *s0++;
		psenc->chlen = 1;
		n--;
		break;
	case 1:
	case 2:
		break;
	default:
		/* illgeal state */
		goto encoding_error;
	}

	c = ei->count[cs = _citrus_EUC_cs(psenc->ch[0] & 0xff)];
	if (c == 0)
		goto encoding_error;
	while (psenc->chlen < c) {
		if (n < 1)
			goto restart;
		psenc->ch[psenc->chlen] = *s0++;
		psenc->chlen++;
		n--;
	}
	*s = s0;

	switch (cs) {
	case 3:
	case 2:
		/* skip SS2/SS3 */
		len = c - 1;
		s1 = &psenc->ch[1];
		break;
	case 1:
	case 0:
		len = c;
		s1 = &psenc->ch[0];
		break;
	default:
		goto encoding_error;
	}
	wchar = 0;
	while (len-- > 0)
		wchar = (wchar << 8) | (*s1++ & 0xff);
	wchar = (wchar & ~ei->mask) | ei->bits[cs];

	psenc->chlen = 0;
	if (pwc)
		*pwc = wchar;
	*nresult = wchar ? (size_t)(c - chlenbak) : 0;
	return (0);

encoding_error:
	psenc->chlen = 0;
	*nresult = (size_t)-1;
	return (EILSEQ);

restart:
	*nresult = (size_t)-2;
	*s = s0;
	return (0);
}

static int
_citrus_EUC_wcrtomb_priv(_EUCEncodingInfo *ei, char *s, size_t n, wchar_t wc,
    _EUCState *psenc __unused, size_t *nresult)
{
	wchar_t m, nm;
	unsigned int cs;
	int ret;
	short i;

	m = wc & ei->mask;
	nm = wc & ~m;

	for (cs = 0; cs < sizeof(ei->count) / sizeof(ei->count[0]); cs++)
		if (m == ei->bits[cs])
			break;
	/* fallback case - not sure if it is necessary */
	if (cs == sizeof(ei->count) / sizeof(ei->count[0]))
		cs = 1;

	i = ei->count[cs];
	if (n < (unsigned)i) {
		ret = E2BIG;
		goto err;
	}
	m = (cs) ? 0x80 : 0x00;
	switch (cs) {
	case 2:
		*s++ = _SS2;
		i--;
		break;
	case 3:
		*s++ = _SS3;
		i--;
		break;
	}

	while (i-- > 0)
		*s++ = ((nm >> (i << 3)) & 0xff) | m;

	*nresult = (size_t)ei->count[cs];
	return (0);

err:
	*nresult = (size_t)-1;
	return (ret);
}

static __inline int
/*ARGSUSED*/
_citrus_EUC_stdenc_wctocs(_EUCEncodingInfo * __restrict ei,
    _csid_t * __restrict csid, _index_t * __restrict idx, wchar_t wc)
{
	wchar_t m, nm;

	m = wc & ei->mask;
	nm = wc & ~m;

	*csid = (_citrus_csid_t)m;
	*idx  = (_citrus_index_t)nm;

	return (0);
}

static __inline int
/*ARGSUSED*/
_citrus_EUC_stdenc_cstowc(_EUCEncodingInfo * __restrict ei,
    wchar_t * __restrict wc, _csid_t csid, _index_t idx)
{

	if ((csid & ~ei->mask) != 0 || (idx & ei->mask) != 0)
		return (EINVAL);

	*wc = (wchar_t)csid | (wchar_t)idx;

	return (0);
}

static __inline int
/*ARGSUSED*/
_citrus_EUC_stdenc_get_state_desc_generic(_EUCEncodingInfo * __restrict ei __unused,
    _EUCState * __restrict psenc, int * __restrict rstate)
{

	*rstate = (psenc->chlen == 0) ? _STDENC_SDGEN_INITIAL :
	    _STDENC_SDGEN_INCOMPLETE_CHAR;
	return (0);
}

static int
/*ARGSUSED*/
_citrus_EUC_encoding_module_init(_EUCEncodingInfo * __restrict ei,
    const void * __restrict var, size_t lenvar)
{

	return (_citrus_EUC_parse_variable(ei, var, lenvar));
}

static void
/*ARGSUSED*/
_citrus_EUC_encoding_module_uninit(_EUCEncodingInfo * __restrict ei __unused)
{

}

/* ----------------------------------------------------------------------
 * public interface for stdenc
 */

_CITRUS_STDENC_DECLS(EUC);
_CITRUS_STDENC_DEF_OPS(EUC);

#include "citrus_stdenc_template.h"