/*
 * conversion between BIG5 and Mule Internal Code(CNS 116643-1992
 * plane 1 and plane 2).
 * This program is partially copied from lv(Multilingual file viewer)
 * and slightly modified. lv is written and copyrighted by NARITA Tomio
 * (nrt@web.ad.jp).
 * 
 * 1999/1/15 Tatsuo Ishii
 *
 * $Id: big5.c,v 1.1 1999/02/02 18:51:22 momjian Exp $
 */

#include "mb/pg_wchar.h"

typedef struct {
  unsigned short code, peer;
} codes_t;

/* map Big5 Level 1 to CNS 11643-1992 Plane 1 */
static codes_t big5Level1ToCnsPlane1[ 25 ] = {	/* range */
  { 0xA140, 0x2121 },
  { 0xA1F6, 0x2258 },
  { 0xA1F7, 0x2257 },
  { 0xA1F8, 0x2259 },
  { 0xA2AF, 0x2421 },
  { 0xA3C0, 0x4221 },
  { 0xa3e1, 0x0000 },
  { 0xA440, 0x4421 },
  { 0xACFE, 0x5753 },
  { 0xacff, 0x0000 },
  { 0xAD40, 0x5323 },
  { 0xAFD0, 0x5754 },
  { 0xBBC8, 0x6B51 },
  { 0xBE52, 0x6B50 },
  { 0xBE53, 0x6F5C },
  { 0xC1AB, 0x7536 },
  { 0xC2CB, 0x7535 },
  { 0xC2CC, 0x7737 },
  { 0xC361, 0x782E },
  { 0xC3B9, 0x7865 },
  { 0xC3BA, 0x7864 },
  { 0xC3BB, 0x7866 },
  { 0xC456, 0x782D },
  { 0xC457, 0x7962 },
  { 0xc67f, 0x0000 }
};

/* map CNS 11643-1992 Plane 1 to Big5 Level 1 */
static codes_t cnsPlane1ToBig5Level1[ 26 ] = {	/* range */
  { 0x2121, 0xA140 },
  { 0x2257, 0xA1F7 },
  { 0x2258, 0xA1F6 },
  { 0x2259, 0xA1F8 },
  { 0x234f, 0x0000 },
  { 0x2421, 0xA2AF },
  { 0x2571, 0x0000 },
  { 0x4221, 0xA3C0 },
  { 0x4242, 0x0000 },
  { 0x4421, 0xA440 },
  { 0x5323, 0xAD40 },
  { 0x5753, 0xACFE },
  { 0x5754, 0xAFD0 },
  { 0x6B50, 0xBE52 },
  { 0x6B51, 0xBBC8 },
  { 0x6F5C, 0xBE53 },
  { 0x7535, 0xC2CB },
  { 0x7536, 0xC1AB },
  { 0x7737, 0xC2CC },
  { 0x782D, 0xC456 },
  { 0x782E, 0xC361 },
  { 0x7864, 0xC3BA },
  { 0x7865, 0xC3B9 },
  { 0x7866, 0xC3BB },
  { 0x7962, 0xC457 },
  { 0x7d4c, 0x0000 }
};

/* map Big5 Level 2 to CNS 11643-1992 Plane 2 */
static codes_t big5Level2ToCnsPlane2[ 48 ] = {	/* range */
  { 0xC940, 0x2121 },
  { 0xc94a, 0x0000 },
  { 0xC94B, 0x212B },
  { 0xC96C, 0x214D },
  { 0xC9BE, 0x214C },
  { 0xC9BF, 0x217D },
  { 0xC9ED, 0x224E },
  { 0xCAF7, 0x224D },
  { 0xCAF8, 0x2439 },
  { 0xD77A, 0x3F6A },
  { 0xD77B, 0x387E },
  { 0xDBA7, 0x3F6B },
  { 0xDDFC, 0x4176 },
  { 0xDDFD, 0x4424 },
  { 0xE8A3, 0x554C },
  { 0xE976, 0x5723 },
  { 0xEB5B, 0x5A29 },
  { 0xEBF1, 0x554B },
  { 0xEBF2, 0x5B3F },
  { 0xECDE, 0x5722 },
  { 0xECDF, 0x5C6A },
  { 0xEDAA, 0x5D75 },
  { 0xEEEB, 0x642F },
  { 0xEEEC, 0x6039 },
  { 0xF056, 0x5D74 },
  { 0xF057, 0x6243 },
  { 0xF0CB, 0x5A28 },
  { 0xF0CC, 0x6337 },
  { 0xF163, 0x6430 },
  { 0xF16B, 0x6761 },
  { 0xF16C, 0x6438 },
  { 0xF268, 0x6934 },
  { 0xF269, 0x6573 },
  { 0xF2C3, 0x664E },
  { 0xF375, 0x6762 },
  { 0xF466, 0x6935 },
  { 0xF4B5, 0x664D },
  { 0xF4B6, 0x6962 },
  { 0xF4FD, 0x6A4C },
  { 0xF663, 0x6A4B },
  { 0xF664, 0x6C52 },
  { 0xF977, 0x7167 },
  { 0xF9C4, 0x7166 },
  { 0xF9C5, 0x7234 },
  { 0xF9C6, 0x7240 },
  { 0xF9C7, 0x7235 },
  { 0xF9D2, 0x7241 },
  { 0xf9d6, 0x0000 }
};

/* map CNS 11643-1992 Plane 2 to Big5 Level 2 */
static codes_t cnsPlane2ToBig5Level2[ 49 ] = {	/* range */
  { 0x2121, 0xC940 },
  { 0x212B, 0xC94B },
  { 0x214C, 0xC9BE },
  { 0x214D, 0xC96C },
  { 0x217D, 0xC9BF },
  { 0x224D, 0xCAF7 },
  { 0x224E, 0xC9ED },
  { 0x2439, 0xCAF8 },
  { 0x387E, 0xD77B },
  { 0x3F6A, 0xD77A },
  { 0x3F6B, 0xDBA7 },
  { 0x4424, 0x0000 },
  { 0x4176, 0xDDFC },
  { 0x4177, 0x0000 },
  { 0x4424, 0xDDFD },
  { 0x554B, 0xEBF1 },
  { 0x554C, 0xE8A3 },
  { 0x5722, 0xECDE },
  { 0x5723, 0xE976 },
  { 0x5A28, 0xF0CB },
  { 0x5A29, 0xEB5B },
  { 0x5B3F, 0xEBF2 },
  { 0x5C6A, 0xECDF },
  { 0x5D74, 0xF056 },
  { 0x5D75, 0xEDAA },
  { 0x6039, 0xEEEC },
  { 0x6243, 0xF057 },
  { 0x6337, 0xF0CC },
  { 0x642F, 0xEEEB },
  { 0x6430, 0xF163 },
  { 0x6438, 0xF16C },
  { 0x6573, 0xF269 },
  { 0x664D, 0xF4B5 },
  { 0x664E, 0xF2C3 },
  { 0x6761, 0xF16B },
  { 0x6762, 0xF375 },
  { 0x6934, 0xF268 },
  { 0x6935, 0xF466 },
  { 0x6962, 0xF4B6 },
  { 0x6A4B, 0xF663 },
  { 0x6A4C, 0xF4FD },
  { 0x6C52, 0xF664 },
  { 0x7166, 0xF9C4 },
  { 0x7167, 0xF977 },
  { 0x7234, 0xF9C5 },
  { 0x7235, 0xF9C7 },
  { 0x7240, 0xF9C6 },
  { 0x7241, 0xF9D2 },
  { 0x7245, 0x0000 }
};

/* Big Five Level 1 Correspondence to CNS 11643-1992 Plane 4 */
static unsigned short b1c4[][2] = {
  {0xC879, 0x2123},
  {0xC87B, 0x2124},
  {0xC87D, 0x212A},
  {0xC8A2, 0x2152}
};

/* Big Five Level 2 Correspondence to CNS 11643-1992 Plane 3 */
static unsigned short b2c3[][2] = {
  {0xF9D6, 0x4337},
  {0xF9D7, 0x4F50},
  {0xF9D8, 0x444E},
  {0xF9D9, 0x504A},
  {0xF9DA, 0x2C5D},
  {0xF9DB, 0x3D7E},
  {0xF9DC, 0x4B5C}
};

static unsigned short BinarySearchRange
(codes_t *array, int high, unsigned short code )
{
  int low, mid, distance, tmp;

  low = 0;
  mid = high >> 1;

  for( ; low <= high ; mid = ( low + high ) >> 1 ){
    if( ( array[ mid ].code <= code ) && ( array[ mid + 1 ].code > code ) ){
      if( 0 == array[ mid ].peer )
	return 0;
      if( code >= 0xa140U ){
	/* big5 to cns */
	tmp = ( ( code & 0xff00 ) - ( array[ mid ].code & 0xff00 ) ) >> 8;
	high = code & 0x00ff;
	low = array[ mid ].code & 0x00ff;
	/*
	 * NOTE: big5 high_byte: 0xa1-0xfe, low_byte: 0x40-0x7e, 0xa1-0xfe
	 *                                 (radicals: 0x00-0x3e, 0x3f-0x9c)
	 *  big5 radix is 0x9d.                     [region_low, region_high]
	 *  We should remember big5 has two different regions (above).
	 *  There is a bias for the distance between these regions.
	 *    0xa1 - 0x7e + bias = 1 (Distance between 0xa1 and 0x7e is 1.)
	 *                  bias = - 0x22.
	 */
	distance = tmp * 0x9d + high - low +
	  ( high >= 0xa1 ? ( low >= 0xa1 ? 0 : - 0x22 )
	   : ( low >= 0xa1 ? + 0x22 : 0 ) );
	/*
	 * NOTE: we have to convert the distance into a code point.
	 *       The code point's low_byte is 0x21 plus mod_0x5e.
	 *       In the first, we extract the mod_0x5e of the starting
	 *       code point, subtracting 0x21, and add distance to it.
	 *       Then we calculate again mod_0x5e of them, and restore
	 *       the final codepoint, adding 0x21.
	 */
	tmp = ( array[ mid ].peer & 0x00ff ) + distance - 0x21;
	tmp = ( array[ mid ].peer & 0xff00 ) + ( ( tmp / 0x5e ) << 8 )
	  + 0x21 + tmp % 0x5e;
	return tmp;
      } else {
	/* cns to big5 */
	tmp = ( ( code & 0xff00 ) - ( array[ mid ].code & 0xff00 ) ) >> 8;
	/*
	 * NOTE: ISO charsets ranges between 0x21-0xfe (94charset).
	 *       Its radix is 0x5e. But there is no distance bias like big5.
	 */
	distance = tmp * 0x5e
	  + ( (int)( code & 0x00ff ) - (int)( array[ mid ].code & 0x00ff ) );
	/*
	 * NOTE: Similar to big5 to cns conversion, we extract mod_0x9d and
	 *       restore mod_0x9d into a code point.
	 */
	low = array[ mid ].peer & 0x00ff;
	tmp = low + distance - ( low >= 0xa1 ? 0x62 : 0x40 );
	low = tmp % 0x9d;
	tmp = ( array[ mid ].peer & 0xff00 ) + ( ( tmp / 0x9d ) << 8 )
	  + ( low > 0x3e ? 0x62 : 0x40 ) + low;
	return tmp;
      }
    } else if( array[ mid ].code > code ){
      high = mid - 1;
    } else {
      low = mid + 1;
    }
  }

  return 0;
}


unsigned short BIG5toCNS(unsigned short big5, unsigned char *lc )
{
  unsigned short cns = 0;
  int i;

  if( big5 < 0xc940U ){
    /* level 1 */

    for (i=0;i<sizeof(b1c4)/sizeof(unsigned short);i++) {
      if (b1c4[i][0] == big5) {
	*lc = LC_CNS11643_4;
	return(b1c4[i][1] | 0x8080U);
      }
    }

    if( 0 < (cns = BinarySearchRange( big5Level1ToCnsPlane1, 23, big5 )) )
      *lc = LC_CNS11643_1;
  } else if( big5 == 0xc94aU ){
    /* level 2 */
    *lc = LC_CNS11643_1;
    cns = 0x4442;
  } else {
    /* level 2 */
    for (i=0;i<sizeof(b2c3)/sizeof(unsigned short);i++) {
      if (b2c3[i][0] == big5) {
	*lc = LC_CNS11643_3;
	return(b2c3[i][1]);
      }
    }

    if( 0 < (cns = BinarySearchRange( big5Level2ToCnsPlane2, 46, big5 )) )
      *lc = LC_CNS11643_2;
  }

  if( 0 == cns ){	/* no mapping Big5 to CNS 11643-1992 */
    *lc = 0;
    return (unsigned short)'?';
  }

  return cns | 0x8080;
}

unsigned short CNStoBIG5( unsigned short cns, unsigned char lc )
{
  int i;
  unsigned int big5 = 0;

  cns &= 0x7f7f;

  switch( lc ){
  case LC_CNS11643_1:
    big5 = BinarySearchRange( cnsPlane1ToBig5Level1, 24, cns );
    break;
  case LC_CNS11643_2:
    big5 = BinarySearchRange( cnsPlane2ToBig5Level2, 47, cns );
    break;
  case LC_CNS11643_3:
    for (i=0;i<sizeof(b2c3)/sizeof(unsigned short);i++) {
      if (b2c3[i][1] == cns) {
	return(b2c3[i][0]);
      }
    }
    break;
  case LC_CNS11643_4:
    for (i=0;i<sizeof(b1c4)/sizeof(unsigned short);i++) {
      if (b1c4[i][1] == cns) {
	return(b1c4[i][0]);
      }
    }
  default:
    break;
  }
  return big5;
}
