/*      $NetBSD: citrus_utf1632.c,v 1.9 2008/06/14 16:01:08 tnozaki Exp $       */

/*-
 * SPDX-License-Identifier: BSD-2-Clause
 *
 * Copyright (c)2003 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.
 */

#include <sys/cdefs.h>
#include <sys/endian.h>
#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_types.h"
#include "citrus_module.h"
#include "citrus_stdenc.h"
#include "citrus_bcs.h"

#include "citrus_utf1632.h"


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

typedef struct {
        int              chlen;
        int              current_endian;
        uint8_t          ch[4];
} _UTF1632State;

#define _ENDIAN_UNKNOWN         0
#define _ENDIAN_BIG             1
#define _ENDIAN_LITTLE          2
#if BYTE_ORDER == BIG_ENDIAN
#define _ENDIAN_INTERNAL        _ENDIAN_BIG
#define _ENDIAN_SWAPPED         _ENDIAN_LITTLE
#else
#define _ENDIAN_INTERNAL        _ENDIAN_LITTLE
#define _ENDIAN_SWAPPED _ENDIAN_BIG
#endif
#define _MODE_UTF32             0x00000001U
#define _MODE_FORCE_ENDIAN      0x00000002U

typedef struct {
        int              preffered_endian;
        unsigned int     cur_max;
        unsigned int     cur_min;
        uint32_t         mode;
} _UTF1632EncodingInfo;

#define _FUNCNAME(m)                    _citrus_UTF1632_##m
#define _ENCODING_INFO                  _UTF1632EncodingInfo
#define _ENCODING_STATE                 _UTF1632State
#define _ENCODING_MB_CUR_MAX(_ei_)      ((_ei_)->cur_max)
#define _ENCODING_MB_CUR_MIN(_ei_)      ((_ei_)->cur_min)
#define _ENCODING_IS_STATE_DEPENDENT    0
#define _STATE_NEEDS_EXPLICIT_INIT(_ps_)        0


static __inline void
/*ARGSUSED*/
_citrus_UTF1632_init_state(_UTF1632EncodingInfo *ei __unused,
    _UTF1632State *s)
{

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

static int
_citrus_UTF1632_mbrtowc_priv(_UTF1632EncodingInfo *ei, wchar_t *pwc,
    char **s, size_t n, _UTF1632State *psenc, size_t *nresult)
{
        char *s0;
        size_t result;
        wchar_t wc = L'\0';
        int chlenbak, endian, needlen;

        s0 = *s;

        if (s0 == NULL) {
                _citrus_UTF1632_init_state(ei, psenc);
                *nresult = 0; /* state independent */
                return (0);
        }

        result = 0;
        chlenbak = psenc->chlen;

refetch:
        needlen = ((ei->mode & _MODE_UTF32) != 0 || chlenbak >= 2) ? 4 : 2;

        while (chlenbak < needlen) {
                if (n == 0)
                        goto restart;
                psenc->ch[chlenbak++] = *s0++;
                n--;
                result++;
        }

        /* judge endian marker */
        if ((ei->mode & _MODE_UTF32) == 0) {
                /* UTF16 */
                if (psenc->ch[0] == 0xFE && psenc->ch[1] == 0xFF) {
                        psenc->current_endian = _ENDIAN_BIG;
                        chlenbak = 0;
                        goto refetch;
                } else if (psenc->ch[0] == 0xFF && psenc->ch[1] == 0xFE) {
                        psenc->current_endian = _ENDIAN_LITTLE;
                        chlenbak = 0;
                        goto refetch;
                }
        } else {
                /* UTF32 */
                if (psenc->ch[0] == 0x00 && psenc->ch[1] == 0x00 &&
                    psenc->ch[2] == 0xFE && psenc->ch[3] == 0xFF) {
                        psenc->current_endian = _ENDIAN_BIG;
                        chlenbak = 0;
                        goto refetch;
                } else if (psenc->ch[0] == 0xFF && psenc->ch[1] == 0xFE &&
                           psenc->ch[2] == 0x00 && psenc->ch[3] == 0x00) {
                        psenc->current_endian = _ENDIAN_LITTLE;
                        chlenbak = 0;
                        goto refetch;
                }
        }
        endian = ((ei->mode & _MODE_FORCE_ENDIAN) != 0 ||
            psenc->current_endian == _ENDIAN_UNKNOWN) ? ei->preffered_endian :
            psenc->current_endian;

        /* get wc */
        if ((ei->mode & _MODE_UTF32) == 0) {
                /* UTF16 */
                if (needlen == 2) {
                        switch (endian) {
                        case _ENDIAN_LITTLE:
                                wc = (psenc->ch[0] |
                                    ((wchar_t)psenc->ch[1] << 8));
                                break;
                        case _ENDIAN_BIG:
                                wc = (psenc->ch[1] |
                                    ((wchar_t)psenc->ch[0] << 8));
                                break;
                        default:
                                goto ilseq;
                        }
                        if (wc >= 0xD800 && wc <= 0xDBFF) {
                                /* surrogate high */
                                needlen = 4;
                                goto refetch;
                        }
                } else {
                        /* surrogate low */
                        wc -= 0xD800; /* wc : surrogate high (see above) */
                        wc <<= 10;
                        switch (endian) {
                        case _ENDIAN_LITTLE:
                                if (psenc->ch[3] < 0xDC || psenc->ch[3] > 0xDF)
                                        goto ilseq;
                                wc |= psenc->ch[2];
                                wc |= (wchar_t)(psenc->ch[3] & 3) << 8;
                                break;
                        case _ENDIAN_BIG:
                                if (psenc->ch[2]<0xDC || psenc->ch[2]>0xDF)
                                        goto ilseq;
                                wc |= psenc->ch[3];
                                wc |= (wchar_t)(psenc->ch[2] & 3) << 8;
                                break;
                        default:
                                goto ilseq;
                        }
                        wc += 0x10000;
                }
        } else {
                /* UTF32 */
                switch (endian) {
                case _ENDIAN_LITTLE:
                        wc = (psenc->ch[0] |
                            ((wchar_t)psenc->ch[1] << 8) |
                            ((wchar_t)psenc->ch[2] << 16) |
                            ((wchar_t)psenc->ch[3] << 24));
                        break;
                case _ENDIAN_BIG:
                        wc = (psenc->ch[3] |
                            ((wchar_t)psenc->ch[2] << 8) |
                            ((wchar_t)psenc->ch[1] << 16) |
                            ((wchar_t)psenc->ch[0] << 24));
                        break;
                default:
                        goto ilseq;
                }
                if (wc >= 0xD800 && wc <= 0xDFFF)
                        goto ilseq;
        }


        *pwc = wc;
        psenc->chlen = 0;
        *nresult = result;
        *s = s0;

        return (0);

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

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

static int
_citrus_UTF1632_wcrtomb_priv(_UTF1632EncodingInfo *ei, char *s, size_t n,
    wchar_t wc, _UTF1632State *psenc, size_t *nresult)
{
        wchar_t wc2;
        static const char _bom[4] = {
            0x00, 0x00, 0xFE, 0xFF,
        };
        const char *bom = &_bom[0];
        size_t cnt;

        cnt = (size_t)0;
        if (psenc->current_endian == _ENDIAN_UNKNOWN) {
                if ((ei->mode & _MODE_FORCE_ENDIAN) == 0) {
                        if (ei->mode & _MODE_UTF32)
                                cnt = 4;
                        else {
                                cnt = 2;
                                bom += 2;
                        }
                        if (n < cnt)
                                goto e2big;
                        memcpy(s, bom, cnt);
                        s += cnt, n -= cnt;
                }
                psenc->current_endian = ei->preffered_endian;
        }

        wc2 = 0;
        if ((ei->mode & _MODE_UTF32)==0) {
                /* UTF16 */
                if (wc > 0xFFFF) {
                        /* surrogate */
                        if (wc > 0x10FFFF)
                                goto ilseq;
                        if (n < 4)
                                goto e2big;
                        cnt += 4;
                        wc -= 0x10000;
                        wc2 = (wc & 0x3FF) | 0xDC00;
                        wc = (wc>>10) | 0xD800;
                } else {
                        if (n < 2)
                                goto e2big;
                        cnt += 2;
                }

surrogate:
                switch (psenc->current_endian) {
                case _ENDIAN_BIG:
                        s[1] = wc;
                        s[0] = (wc >>= 8);
                        break;
                case _ENDIAN_LITTLE:
                        s[0] = wc;
                        s[1] = (wc >>= 8);
                        break;
                }
                if (wc2 != 0) {
                        wc = wc2;
                        wc2 = 0;
                        s += 2;
                        goto surrogate;
                }
        } else {
                /* UTF32 */
                if (wc >= 0xD800 && wc <= 0xDFFF)
                        goto ilseq;
                if (n < 4)
                        goto e2big;
                cnt += 4;
                switch (psenc->current_endian) {
                case _ENDIAN_BIG:
                        s[3] = wc;
                        s[2] = (wc >>= 8);
                        s[1] = (wc >>= 8);
                        s[0] = (wc >>= 8);
                        break;
                case _ENDIAN_LITTLE:
                        s[0] = wc;
                        s[1] = (wc >>= 8);
                        s[2] = (wc >>= 8);
                        s[3] = (wc >>= 8);
                        break;
                }
        }
        *nresult = cnt;

        return (0);

ilseq:
        *nresult = (size_t)-1;
        return (EILSEQ);
e2big:
        *nresult = (size_t)-1;
        return (E2BIG);
}

static void
parse_variable(_UTF1632EncodingInfo * __restrict ei,
    const void * __restrict var, size_t lenvar)
{
        const char *p;

        p = var;
        while (lenvar > 0) {
                switch (*p) {
                case 'B':
                case 'b':
                        MATCH(big, ei->preffered_endian = _ENDIAN_BIG);
                        break;
                case 'L':
                case 'l':
                        MATCH(little, ei->preffered_endian = _ENDIAN_LITTLE);
                        break;
                case 'i':
                case 'I':
                        MATCH(internal, ei->preffered_endian = _ENDIAN_INTERNAL);
                        break;
                case 's':
                case 'S':
                        MATCH(swapped, ei->preffered_endian = _ENDIAN_SWAPPED);
                        break;
                case 'F':
                case 'f':
                        MATCH(force, ei->mode |= _MODE_FORCE_ENDIAN);
                        break;
                case 'U':
                case 'u':
                        MATCH(utf32, ei->mode |= _MODE_UTF32);
                        break;
                }
                p++;
                lenvar--;
        }
}

static int
/*ARGSUSED*/
_citrus_UTF1632_encoding_module_init(_UTF1632EncodingInfo * __restrict ei,
    const void * __restrict var, size_t lenvar)
{

        memset((void *)ei, 0, sizeof(*ei));

        parse_variable(ei, var, lenvar);

        ei->cur_min = ((ei->mode&_MODE_UTF32) == 0) ? 2 : 4;
        ei->cur_max = ((ei->mode&_MODE_UTF32) == 0) ? 6 : 8;
        /* 6: endian + surrogate */
        /* 8: endian + normal */

        if (ei->preffered_endian == _ENDIAN_UNKNOWN) {
                ei->preffered_endian = _ENDIAN_BIG;
        }

        return (0);
}

static void
/*ARGSUSED*/
_citrus_UTF1632_encoding_module_uninit(_UTF1632EncodingInfo *ei __unused)
{

}

static __inline int
/*ARGSUSED*/
_citrus_UTF1632_stdenc_wctocs(_UTF1632EncodingInfo * __restrict ei __unused,
     _csid_t * __restrict csid, _index_t * __restrict idx, _wc_t wc)
{

        *csid = 0;
        *idx = (_index_t)wc;

        return (0);
}

static __inline int
/*ARGSUSED*/
_citrus_UTF1632_stdenc_cstowc(_UTF1632EncodingInfo * __restrict ei __unused,
    _wc_t * __restrict wc, _csid_t csid, _index_t idx)
{

        if (csid != 0)
                return (EILSEQ);

        *wc = (_wc_t)idx;

        return (0);
}

static __inline int
/*ARGSUSED*/
_citrus_UTF1632_stdenc_get_state_desc_generic(_UTF1632EncodingInfo * __restrict ei __unused,
    _UTF1632State * __restrict psenc, int * __restrict rstate)
{

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

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

_CITRUS_STDENC_DECLS(UTF1632);
_CITRUS_STDENC_DEF_OPS(UTF1632);

#include "citrus_stdenc_template.h"