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big5.c
/*
 * 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
 *
 * $PostgreSQL: pgsql/src/backend/utils/mb/conversion_procs/euc_tw_and_big5/big5.c,v 1.7 2005/11/22 18:17:26 momjian Exp $
 */

/* can be used in either frontend or backend */
#include "postgres_fe.h"

#include "mb/pg_wchar.h"

00018 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) * 2); 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) * 2); i++)
            {
                  if (b2c3[i][0] == big5)
                  {
                        *lc = LC_CNS11643_3;
                        return (b2c3[i][1] | 0x8080U);
                  }
            }

            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) * 2); i++)
                  {
                        if (b2c3[i][1] == cns)
                              return (b2c3[i][0]);
                  }
                  break;
            case LC_CNS11643_4:
                  for (i = 0; i < sizeof(b1c4) / (sizeof(unsigned short) * 2); i++)
                  {
                        if (b1c4[i][1] == cns)
                              return (b1c4[i][0]);
                  }
            default:
                  break;
      }
      return big5;
}

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