/*
 * 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 <errno.h>
#include <stdlib.h>
#include <sys/types.h>
#include <unicode_gb18030.h>    /* Unicode to GBK mapping table */
#include "common_defs.h"
#include "ucs4.h"

#define MSB     0x80    /* most significant bit */
#define ONEBYTE 0xff    /* right most byte */

#define NON_ID_CHAR '?' /* non-identified character */

#define IS_GBK4BYTES(v)  ( (v) & 0xffff0000 )
#define GBK_LEN_MAX     4


typedef struct _icv_state {
        char    keepc[6];       /* maximum # byte of UTF8 code */
        short   ustate;
        int     _errno;         /* internal errno */
} _iconv_st;

enum _USTATE    { U0, U1, U2, U3, U4, U5, U6, U7 };

int get_gbk_by_unicode(unsigned long, int*, unsigned long*);
static int binsearch(unsigned long x, table_t v[], int n);
int unicode_to_gbk(int unidx, unsigned long gbkcode, char* buf, size_t buflen, int *uconv_num);

/*
 * Open; called from iconv_open()
 */
void *
_icv_open()
{
        _iconv_st *st;

        if ((st = (_iconv_st *)malloc(sizeof(_iconv_st))) == NULL) {
                errno = ENOMEM;
                return ((void *) -1);
        }

        st->ustate = U0;
        st->_errno = 0;
        return ((void *) st);
}


/*
 * Close; called from iconv_close()
 */
void
_icv_close(_iconv_st *st)
{
        if (!st)
                errno = EBADF;
        else
                free(st);
}

#if defined(UCS_2LE) || defined (UCS_2BE) || defined (UCS_4LE) || defined (UCS_4BE)
size_t
_icv_iconv(_iconv_st *st, char **inbuf, size_t *inbytesleft,
                                char **outbuf, size_t *outbytesleft)
{
        unsigned char   c1, c2;
#if defined(UCS_4LE) || defined (UCS_4BE)
        unsigned char   c3, c4;
#endif
        int             n, unidx;
        unsigned long   unichr;
        unsigned long   gbkcode;
        int             uconv_num = 0;

        if (st == NULL) {
                errno = EBADF;
                return ((size_t) -1);
        }

        if (inbuf == NULL || *inbuf == NULL) { /* Reset request. */
                st->ustate = U0;
                st->_errno = 0;
                return ((size_t) 0);
        }

        st->_errno = 0;         /* reset internal errno */
        errno = 0;              /* reset external errno */

        while (*inbytesleft > ICV_FETCH_UCS_SIZE-1 && *outbytesleft > 0) {

                int     size = 0;
                int     uconv_num_internal = 0;

                c1 = *(*inbuf + size++);
                c2 = *(*inbuf + size++);
#if defined(UCS_4LE) || defined (UCS_4BE)
                c3 = *(*inbuf + size++);
                c4 = *(*inbuf + size++);
#endif

#if defined(UCS_2LE)
                unichr = (unsigned long) (c1 | (c2<<8));
#elif defined(UCS_2BE)
                unichr = (unsigned long) ((c1<<8) | c2);
#elif defined(UCS_4LE)
                unichr = (unsigned long) (c1 | (c2<<8) | (c3)<<16 | (c4<<24));
#else
                unichr = (unsigned long) ((c1<<24) | (c2<<16) | (c3<<8) | c4);
#endif

                if (unichr < MSB) { /* ASCII */
                        **outbuf = (char) unichr;
                        (*outbuf)++;
                        (*outbytesleft)--;
                } else {
                        n = get_gbk_by_unicode(unichr, &unidx, &gbkcode);
                        if ( n == -1 ) { /* invalid unicode codepoint */
                                st->_errno = errno = EILSEQ;
                                return ((size_t)-1);
                        }

                        n = unicode_to_gbk(unidx, gbkcode, *outbuf, *outbytesleft, &uconv_num_internal);
                        if (n > 0) {
                                (*outbuf) += n;
                                (*outbytesleft) -= n;

                                uconv_num += uconv_num_internal;
                        } else {
                                return ((size_t)-1);
                        }
                }

                (*inbuf) += size;
                (*inbytesleft) -= size;
        }

        if ( *inbytesleft >0 ) {
                errno =  *outbytesleft? EINVAL: E2BIG;
                return ((size_t)-1);
        }

        return uconv_num;
}
#else
/*
 * Actual conversion; called from iconv()
 */
/*=========================================================
 *
 *       State Machine for interpreting UTF8 code
 *
 *=========================================================
 *               4 byte unicode
 *          +----->------->------------> U5 -----> U6-------> U7---+
 *          |                                                      |
 *          |    3 byte unicode                                    |
 *          +----->------->-------+                                |
 *          |                     |                                |
 *          ^                     v                                |
 *          |  2 byte             U2 ---> U3                       |
 *          |  unicode                    v                        |
 * +------> U0 -------> U1                +-------->U4---+         |
 * ^  ascii |           |                           ^    |         |
 * |        |           +-------->--------->--------+    |         |
 * |        v                                            v         V
 * +----<---+-----<------------<------------<------------+---------+
 *
 *=========================================================*/
size_t
_icv_iconv(_iconv_st *st, char **inbuf, size_t *inbytesleft,
                                char **outbuf, size_t *outbytesleft)
{
        char            c1 = 0, c2 = 0;
        int             n, unidx;
        unsigned long   unichr;
        unsigned long   gbkcode;
        int             uconv_num = 0;
        int             utf8_len = 0;

#ifdef DEBUG
    fprintf(stderr, "==========     iconv(): UTF2 --> GBK2K     ==========\n");
#endif
        if (st == NULL) {
                errno = EBADF;
                return ((size_t) -1);
        }

        if (inbuf == NULL || *inbuf == NULL) { /* Reset request. */
                st->ustate = U0;
                st->_errno = 0;
                return ((size_t) 0);
        }

        st->_errno = 0;         /* reset internal errno */
        errno = 0;              /* reset external errno */

        /* a state machine for interpreting UTF8 code */
        while (*inbytesleft > 0 && *outbytesleft > 0) {

                uchar_t  first_byte;
                int      uconv_num_internal = 0;

                switch (st->ustate) {
                case U0:                /* assuming ASCII in the beginning */
                        if ((**inbuf & MSB) == 0) {     /* ASCII */
                                **outbuf = **inbuf;
                                (*outbuf)++;
                                (*outbytesleft)--;
                        } else {
                                if ((**inbuf & 0xe0) == 0xc0) { /* 2 byte unicode 0xc0..0xdf */
                                    /* invalid sequence if the first char is either 0xc0 or 0xc1 */
                                    if ( number_of_bytes_in_utf8_char[((uchar_t)**inbuf)] == ICV_TYPE_ILLEGAL_CHAR )
                                        st->_errno = errno = EILSEQ;
                                    else {
                                        st->ustate = U1;
                                        st->keepc[0] = **inbuf;
                                    }
                                } else if ((**inbuf & 0xf0) == 0xe0) {  /* 3 byte 0xe0..0xef */
                                        st->ustate = U2;
                                        st->keepc[0] = **inbuf;
                                } else {
                                     /* four bytes of UTF-8 sequences */
                                     if ( number_of_bytes_in_utf8_char[((uchar_t)**inbuf)] == ICV_TYPE_ILLEGAL_CHAR )
                                        st->_errno = errno = EILSEQ;
                                     else {
                                        st->ustate = U5;
                                        st->keepc[0] = **inbuf;
                                     }
                                }
                        }
                        break;
                case U1:                /* 2 byte unicode */
                        if ((**inbuf & 0xc0) == MSB) {
                                utf8_len = 2;
                                st->keepc[1] = **inbuf;

                                c1 = (st->keepc[0]&0x1c)>>2;
                                c2 = ((st->keepc[0]&0x03)<<6) | ((st->keepc[1])&0x3f);

                                st->ustate = U4;
#ifdef DEBUG
    fprintf(stderr, "UTF8: %02x%02x   --> ",
        st->keepc[0]&ONEBYTE, st->keepc[1]&ONEBYTE);
#endif
                                continue;       /* should not advance *inbuf */
                        } else {
                                st->_errno = errno = EILSEQ;
                        }
                        break;
                case U2:                /* 3 byte unicode - 2nd byte */
                        first_byte = (uchar_t)st->keepc[0];

                        /* if the first byte is 0xed, it is illegal sequence if the second
                         * one is between 0xa0 and 0xbf because surrogate section is ill-formed
                         */
                        if (((uchar_t)**inbuf) < valid_min_2nd_byte[first_byte] ||
                             ((uchar_t)**inbuf) > valid_max_2nd_byte[first_byte] )
                                st->_errno = errno = EILSEQ;
                        else
                           {
                                st->ustate = U3;
                                st->keepc[1] = **inbuf;
                           }
                        break;
                case U3:                /* 3 byte unicode - 3rd byte */
                        if ((**inbuf & 0xc0) == MSB) {
                                st->ustate = U4;
                                utf8_len = 3;
                                st->keepc[2] = **inbuf;
                                c1 = ((st->keepc[0]&0x0f)<<4) |
                                        ((st->keepc[1]&0x3c)>>2);
                                c2 = ((st->keepc[1]&0x03)<<6) | ((**inbuf)&0x3f);
#ifdef DEBUG
    fprintf(stderr, "UTF8: %02x%02x%02x --> ", st->keepc[0]&ONEBYTE,
                st->keepc[1]&ONEBYTE, **inbuf&ONEBYTE);
#endif
                                continue;       /* should not advance *inbuf */
                        } else {
                                st->_errno = errno = EILSEQ;
                        }
                        break;
                case U4:
                        unichr = (unsigned long) ((c1 & ONEBYTE) << 8) + (c2 & ONEBYTE);
                        n = get_gbk_by_unicode(unichr, &unidx, &gbkcode);
                        if ( n == -1 ) { /* unicode is either 0xFFFE or 0xFFFF */
                             st->_errno = errno = EILSEQ;
                             break;
                        }
/* comment the following lines so that converter can ignore the non-GBK characters
                        if (n != 0) {   * legal unicode;illegal GBK *
                                st->_errno = errno = EILSEQ;
                                break;
                        }
*/
                        n = unicode_to_gbk(unidx, gbkcode, *outbuf, *outbytesleft, &uconv_num_internal);
                        if (n > 0) {
                                (*outbuf) += n;
                                (*outbytesleft) -= n;

                                uconv_num += uconv_num_internal;

                                st->ustate = U0;
                        } else {
                                st->_errno = errno;
                        }
                        break;
                 case U5:
                       first_byte = st->keepc[0];

                       /* if the first byte is 0xf0, it is illegal sequence if
                        * the second one is between 0x80 and 0x8f
                        * for Four-Byte UTF: U+10000..U+10FFFF
                        */
                       if (((uchar_t)**inbuf) < valid_min_2nd_byte[first_byte] ||
                           ((uchar_t)**inbuf) > valid_max_2nd_byte[first_byte] )
                           st->_errno = errno = EILSEQ;
                       else {
                           st->ustate = U6;
                           st->keepc[1] = **inbuf;
                       }
                       break;
                 case U6:
                      if ((**inbuf & 0xc0) == MSB) /* 0x80..0xbf */
                       {
                          st->ustate = U7;
                          st->keepc[2] = **inbuf;
                       }
                      else
                          st->_errno = errno = EILSEQ;
                      break;
                 case U7:
                      if ((**inbuf & 0xc0) == MSB) /* 0x80..0xbf */
                       {
                          /* replace with double NON_ID_CHARs */
                          if ( *outbytesleft < 2 ) st->_errno = errno = E2BIG;
                          else
                            {
                               **outbuf = NON_ID_CHAR;
                               *(*outbuf+1) = NON_ID_CHAR;
                               (*outbytesleft) -= 2;

                               uconv_num++;

                               st->ustate = U0;
                            }
                       }
                      else
                          st->_errno = errno = EILSEQ;
                      break;
                 default:                       /* should never come here */
                        st->_errno = errno = EILSEQ;
                        st->ustate = U0;        /* reset state */
                        break;
                }

                if (st->_errno) {
#ifdef DEBUG
    fprintf(stderr, "!!!!!\tst->_errno = %d\tst->ustate = %d\n",
                st->_errno, st->ustate);
#endif
                        break;
                }

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

        if (*inbytesleft == 0 && st->ustate != U0)
                errno = EINVAL;

        if (*inbytesleft > 0 && *outbytesleft == 0)
                errno = E2BIG;

        if (errno) {
                int num_reversed_bytes = 0;

                switch (st->ustate)
                {
                 case U1:
                   num_reversed_bytes = 1;
                   break;
                 case U2:
                   num_reversed_bytes = 1;
                   break;
                 case U3:
                   num_reversed_bytes = 2;
                   break;
                 case U4:
                   num_reversed_bytes = utf8_len - 1;
                   break;
                 case U5:
                   num_reversed_bytes = 1;
                   break;
                 case U6:
                   num_reversed_bytes = 2;
                   break;
                 case U7:
                   num_reversed_bytes = 3;
                   break;
                 }

                /*
                 * if error, *inbuf points to the byte following the last byte
                 * successfully used in conversion.
                 */
                *inbuf -= num_reversed_bytes;
                *inbytesleft += num_reversed_bytes;
                st->ustate = U0;

                return ((size_t) -1);
        }

        return uconv_num;
}
#endif /* UCS_2LE || UCS_2BE || UCS_4LE || UCS_4BE */


/*
 * Match GBK code by UTF8 code;
 * Return: = 0 - match from Unicode to GBK found
 *         = 1 - match from Unicode to GBK NOT found
 *         = -1- illegal sequence
 *
 * Since binary search of the UTF8 to GBK table is necessary, might as well
 * return index and GBK code matching to the unicode.
 */
int get_gbk_by_unicode(unsigned long unicode, int* unidx, unsigned long* gbkcode)
{
        if ( unicode > UCS4_MAXVAL || ext_ucs4_lsw(unicode) > UCS4_PPRC_MAXVAL ) return -1;

        *unidx = binsearch(unicode, unicode_gbk_tab, UNICODEMAX);
        if ((*unidx) >= 0)
                *gbkcode = unicode_gbk_tab[*unidx].value;
        else
                return(1);      /* match from unicode to GBK not found */
#ifdef DEBUG
    fprintf(stderr, "Unicode=%04x, idx=%5d, Big-5=%x ", unicode, *unidx, *gbkcode);
#endif

        return(0);
}


/*
 * ISO/IEC 10646-2000 (Unicode) --> GBK2K
 * Unicode --> UTF8 (FSS-UTF)
 *             (File System Safe Universal Character Set Transformation Format)
 * Return: > 0 - converted with enough space in output buffer
 *         = 0 - no space in outbuf
 */
int unicode_to_gbk(int unidx, unsigned long gbkcode, char* buf, size_t buflen, int *uconv_num)
{
        unsigned long   val;            /* GBK value */
        char            c[GBK_LEN_MAX];
        int             i, length;

        if (unidx < 0) {        /* no match from Unicode to GBK */
                c[0] = c[1] = NON_ID_CHAR;

                *uconv_num = 1;

                length = 2;
        } else {
                if (  ! IS_GBK4BYTES( gbkcode ) ) { /* character within two bytes area */
                        val = gbkcode & 0xffff;
                        c[0] = (char) ((val & 0xff00) >> 8);
                        c[1] = (char) (val & 0xff);
                        length = 2;
                } else { /* character within four bytes area */
                        val = gbkcode & 0xffffffff;
                        c[0] = (char) ( val >> 24 );
                        c[1] = (char) ( val >> 16 );
                        c[2] = (char) ( val >> 8 );
                        c[3] = (char) val;
                        length = 4;
                }
        }

#ifdef DEBUG
    fprintf(stderr, "\t->%x %x<-\n", *buf, *(buf+1));
#endif

        if (buflen < length) {
                errno = E2BIG;
                return(0);
        }

        for ( i = 0; i < length; ++i )
                *buf++ = c[i];

        return length;
}


/* binsearch: find x in v[0] <= v[1] <= ... <= v[n-1] */
static int binsearch(unsigned long x, table_t v[], int n)
{
        int low, high, mid;

        low = 0;
        high = n - 1;
        while (low <= high) {
                mid = (high - low) / 2 + low;
                if (x < v[mid].key)
                        high = mid - 1;
                else if (x > v[mid].key)
                        low = mid + 1;
                else    /* found match */
                        return mid;
        }
        return (-1);    /* no match */
}

/*
vi:ts=8:ai:expandtab
*/