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+/* Canonical decomposition of Unicode characters.
+ Copyright (C) 2009 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 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.
+
+ 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 <http://www.gnu.org/licenses/>. */
+
+#include <config.h>
+
+/* Specification. */
+#include "uninorm.h"
+
+#include <stdlib.h>
+
+#include "decomposition-table.h"
+
+int
+uc_canonical_decomposition (ucs4_t uc, ucs4_t *decomposition)
+{
+ if (uc >= 0xAC00 && uc < 0xD7A4)
+ {
+ /* Hangul syllable. See Unicode standard, chapter 3, section
+ "Hangul Syllable Decomposition", See also the clarification at
+ <http://www.unicode.org/versions/Unicode5.1.0/>, section
+ "Clarification of Hangul Jamo Handling". */
+ unsigned int t;
+
+ uc -= 0xAC00;
+ t = uc % 28;
+
+ 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);
+ /* An entry of (unsigned short)(-1) denotes an absent entry.
+ Otherwise, bit 15 of the entry tells whether the decomposition
+ is a canonical one. */
+ if (entry < 0x8000)
+ {
+ const unsigned char *p;
+ unsigned int element;
+ unsigned int length;
+
+ p = &gl_uninorm_decomp_chars_table[3 * entry];
+ element = (p[0] << 16) | (p[1] << 8) | p[2];
+ /* The first element has 5 bits for the decomposition type. */
+ if (((element >> 18) & 0x1f) != UC_DECOMP_CANONICAL)
+ abort ();
+ 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;
+}
+