/*
 * CDDL HEADER START
 *
 * The contents of this file are subject to the terms of the
 * Common Development and Distribution License (the "License").
 * You may not use this file except in compliance with the License.
 *
 * You can obtain a copy of the license at src/OPENSOLARIS.LICENSE
 * or http://www.opensolaris.org/os/licensing.
 * See the License for the specific language governing permissions
 * and limitations under the License.
 *
 * When distributing Covered Code, include this CDDL HEADER in each
 * file and include the License file at src/OPENSOLARIS.LICENSE.
 * If applicable, add the following below this CDDL HEADER, with the
 * fields enclosed by brackets "[]" replaced with your own identifying
 * information: Portions Copyright [yyyy] [name of copyright owner]
 *
 * CDDL HEADER END
 */
/*
 * Copyright (c) 1995 by Sun Microsystems, Inc.
 * All Rights Reserved.
 */


#include <stdio.h>
#include <libintl.h>
#include <stdlib.h>
#include <errno.h>
#include "ktable.h"
#include "hangulcode.h"

#define MSB 0x80
#define MSB_OFF 0x7f

struct _cv_state {
        int _st_status;
        int _gstate;
};

enum _GSTATE { _nostate, _g0, _g1};

enum SHIFT_STAT {SHIFT_IN, SHIFT_OUT};


typedef struct __conv_desc {
        char                    designated;
        enum { ASCII, WANSUNG } state;
} _conv_desc;


/****  _ I C V _ O P E N  ****/

void* _icv_open()
{
        _conv_desc* cd = (_conv_desc*)malloc(sizeof(_conv_desc));

        if (cd == (_conv_desc*)NULL)
        {
                errno = ENOMEM;
                return((void*)-1);
        }

        cd->designated = 0;
        cd->state = ASCII;

        return((void*)cd);
}  /* end of int _icv_open(). */


/****  _ I C V _ C L O S E  ****/

void _icv_close(_conv_desc* cd)
{
        if (!cd)
                errno = EBADF;
        else
                free((void*)cd);
}  /* end of void _icv_close(_conv_desc*). */


/****  _ I C V _ I C O N V  ****/

size_t _icv_iconv(_conv_desc* cd, char** inbuf, size_t* inbufleft,
                        char** outbuf, size_t* outbufleft)
{
        size_t          ret_val = 0;
        unsigned char*  ib;
        unsigned char*  ob;
        unsigned char*  ibtail;
        unsigned char*  obtail;

        if (!cd)
        {
                errno = EBADF;
                return((size_t)-1);
        }

        if (!inbuf || !(*inbuf))
        {
                if (cd->state == WANSUNG)
                {
                        if (outbufleft && *outbufleft >= 1 && outbuf && *outbuf)
                        {
                                **outbuf = SI;
                                (*outbuf)++;
                                (*outbufleft)--;
                        }
                        else
                        {
                                errno = E2BIG;
                                return((size_t)-1);
                        }
                }

                cd->designated = 0;
                cd->state = ASCII;
                return((size_t)0);
        }

        ib = (unsigned char*)*inbuf;
        ob = (unsigned char*)*outbuf;
        ibtail = ib + *inbufleft;
        obtail = ob + *outbufleft;

        while (ib < ibtail)
        {
                if (!(*ib & 0x80))              /* 7 bits */
                {
                        if (cd->state == WANSUNG)
                        {
                                if (ob >= obtail)
                                {
                                        errno = E2BIG;
                                        ret_val = (size_t)-1;
                                        break;
                                }
                                *ob++ = SI;
                                cd->state = ASCII;
                        }
                        if (ob >= obtail)
                        {
                                errno = E2BIG;
                                ret_val = (size_t)-1;
                                break;
                        }
                        *ob++ = *ib++;
                }
                else
                {
                        if ((ibtail - ib) < 2)
                        {
                                errno = EINVAL;
                                ret_val = (size_t)-1;
                                break;
                        }

                        if (!cd->designated)
                        {
                                if ((obtail - ob) < 4)
                                {
                                        errno = E2BIG;
                                        ret_val = (size_t)-1;
                                        break;
                                }
                                *ob++ = ESC;  *ob++ = '$';
                                *ob++ = ')'; *ob++ = 'C';
                                cd->designated = 1;
                        }
                        if (cd->state == ASCII)
                        {
                                if (ob >= obtail)
                                {
                                        errno = E2BIG;
                                        ret_val = (size_t)-1;
                                        break;
                                }
                                *ob++ = SO;
                                cd->state = WANSUNG;
                        }

                        if ((obtail - ob) < 2)
                        {
                                errno = E2BIG;
                                ret_val = (size_t)-1;
                                break;
                        }
                        *ob++ = *ib++ & 0x7F;
                        *ob++ = *ib++ & 0x7F;
                }
        }

        *inbuf = (char*)ib;
        *inbufleft = ibtail - ib;
        *outbuf = (char*)ob;
        *outbufleft = obtail - ob;

        return(ret_val);
}  /* end of size_t _icv_iconv(_conv_desc*, char**, size_t*, char**, size_t*).*/

void *
_cv_open()
{
        struct _cv_state *st;

        if ((st = (struct _cv_state *)malloc(sizeof(struct _cv_state))) == NULL)
                return ((void *)-1);

        st->_st_status = SHIFT_IN;
        st->_gstate = _nostate;

        return (st);
}

void
_cv_close(struct _cv_state *st)
{
        free(st);
}


size_t
_cv_enconv(struct _cv_state *st, char **inbuf, size_t*inbytesleft,
                                char **outbuf, size_t*outbytesleft)
{
        if (inbuf == NULL || *inbuf == NULL) { /* Reset request. */
                if (st->_st_status == SHIFT_OUT && *outbytesleft > 0)
                {
                    **outbuf = SI;
                    (*outbytesleft)--;
                    (*outbuf)++;
                }
                st->_st_status = SHIFT_IN;
                st->_gstate = _nostate;
                /*
                 * Note that no shift sequence is needed for
                 * thetarget encoding.
                 */
                return (0);
        }

        if ( st->_gstate == _nostate )
                st->_gstate = _g0;

        while (*inbytesleft > 0 && *outbytesleft > 0) {
            if ( **inbuf & MSB ) {
                if (st->_st_status == SHIFT_IN ) {
                    if ( st->_gstate == _g0 ) {
                        /*
                         * Check the outbytesleft : enough to hold ESC sequence
                         */
                        if ( *outbytesleft < 4 ) {
                            break;
                        }

                        st->_gstate = _g1;

                        **outbuf = ESC;
                        (*outbuf)++, (*outbytesleft)--;
                        **outbuf = '$';
                        (*outbuf)++, (*outbytesleft)--;
                        **outbuf = ')';
                        (*outbuf)++, (*outbytesleft)--;
                        **outbuf = 'C';
                        (*outbuf)++, (*outbytesleft)--;

                        if ( *outbytesleft <= 0 )
                            break;
                    }

                    st->_st_status = SHIFT_OUT;
                    **outbuf = SO;
                    (*outbuf)++, (*outbytesleft)--;

                    if ( *outbytesleft <= 0 )
                        break;
                }

                **outbuf = **inbuf & MSB_OFF;
                (*outbuf)++, (*outbytesleft)--;

            } else {
                if (st->_st_status == SHIFT_OUT) {
                    st->_st_status = SHIFT_IN;
                    **outbuf = SI;
                    (*outbuf)++, (*outbytesleft)--;

                    if ( *outbytesleft <= 0 )
                        break;
                }

                **outbuf = **inbuf;
               (*outbuf)++, (*outbytesleft)--;

            }

            (*inbuf)++, (*inbytesleft)--;
        }
        return (*inbytesleft);
}