/* Decomposition of Unicode characters.

   Copyright (C) 2009-2020 Free Software Foundation, Inc.

   Written by Bruno Haible <bruno@clisp.org>, 2009.

   This program is free software: you can redistribute it and/or

   modify it under the terms of either:

     * the GNU Lesser General Public License as published by the Free

       Software Foundation; either version 3 of the License, or (at your

       option) any later version.

   or

     * the GNU General Public License as published by the Free

       Software Foundation; either version 2 of the License, or (at your

       option) any later version.

   or both in parallel, as here.

   This program is distributed in the hope that it will be useful,

   but WITHOUT ANY WARRANTY; without even the implied warranty of

   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU

   Lesser General Public License for more details.

   You should have received a copy of the GNU Lesser General Public License

   along with this program.  If not, see <https://www.gnu.org/licenses/>.  */

#include <config.h>

/* Specification.  */

#include "uninorm.h"

#include "uninorm/decomposition-table.h"

int

uc_decomposition (ucs4_t uc, int *decomp_tag, ucs4_t *decomposition)

{

  if (uc >= 0xAC00 && uc < 0xD7A4)

    {

      /* Hangul syllable.  See Unicode standard, chapter 3, section

         "Hangul Syllable Decomposition",  See also the clarification at

         <https://www.unicode.org/versions/Unicode5.1.0/>, section

         "Clarification of Hangul Jamo Handling".  */

      unsigned int t;

      uc -= 0xAC00;

      t = uc % 28;

      *decomp_tag = UC_DECOMP_CANONICAL;

      if (t == 0)

        {

          unsigned int v, l;

          uc = uc / 28;

          v = uc % 21;

          l = uc / 21;

          decomposition[0] = 0x1100 + l;

          decomposition[1] = 0x1161 + v;

          return 2;

        }

      else

        {

#if 1 /* Return the pairwise decomposition, not the full decomposition.  */

          decomposition[0] = 0xAC00 + uc - t; /* = 0xAC00 + (l * 21 + v) * 28; */

          decomposition[1] = 0x11A7 + t;

          return 2;

#else

          unsigned int v, l;

          uc = uc / 28;

          v = uc % 21;

          l = uc / 21;

          decomposition[0] = 0x1100 + l;

          decomposition[1] = 0x1161 + v;

          decomposition[2] = 0x11A7 + t;

          return 3;

#endif

        }

    }

  else if (uc < 0x110000)

    {

      unsigned short entry = decomp_index (uc);

      if (entry != (unsigned short)(-1))

        {

          const unsigned char *p;

          unsigned int element;

          unsigned int length;

          p = &gl_uninorm_decomp_chars_table[3 * (entry & 0x7FFF)];

          element = (p[0] << 16) | (p[1] << 8) | p[2];

          /* The first element has 5 bits for the decomposition type.  */

          *decomp_tag = (element >> 18) & 0x1f;

          length = 1;

          for (;;)

            {

              /* Every element has an 18 bits wide Unicode code point.  */

              *decomposition = element & 0x3ffff;

              /* Bit 23 tells whether there are more elements,  */

              if ((element & (1 << 23)) == 0)

                break;

              p += 3;

              element = (p[0] << 16) | (p[1] << 8) | p[2];

              decomposition++;

              length++;

            }

          return length;

        }

    }

  return -1;

}