1 /* Copyright (C) 2000 Free Software Foundation, Inc.
2 This file is part of the GNU C Library.
3 Contributed by Bruno Haible <haible@clisp.cons.org>, 2000.
5 The GNU C Library is free software; you can redistribute it and/or
6 modify it under the terms of the GNU Library General Public License as
7 published by the Free Software Foundation; either version 2 of the
8 License, or (at your option) any later version.
10 The GNU C Library is distributed in the hope that it will be useful,
11 but WITHOUT ANY WARRANTY; without even the implied warranty of
12 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
13 Library General Public License for more details.
15 You should have received a copy of the GNU Library General Public
16 License along with the GNU C Library; see the file COPYING.LIB. If not,
17 write to the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
18 Boston, MA 02111-1307, USA. */
20 /* Tables indexed by a wide character are compressed through the use
21 of a multi-level lookup. The compression effect comes from blocks
22 that don't need particular data and from block that can share their
25 /* Bit tables are accessed by cutting wc in four blocks of bits:
26 - the high 32-q-p bits,
31 +------------------+-----+-----+-----+
32 wc = + 32-q-p-5 | q | p | 5 |
33 +------------------+-----+-----+-----+
35 p and q are variable. For 16-bit Unicode it is sufficient to
36 choose p and q such that q+p+5 <= 16.
38 The table contains the following uint32_t words:
40 - s = upper exclusive bound for wc >> (q+p+5),
44 - 1st-level table: s offsets, pointing into the 2nd-level table,
45 - 2nd-level table: k*2^q offsets, pointing into the 3rd-level table,
46 - 3rd-level table: j*2^p words, each containing 32 bits of data.
50 wctype_table_lookup (const char *table, uint32_t wc)
52 uint32_t shift1 = ((const uint32_t *) table)[0];
53 uint32_t index1 = wc >> shift1;
54 uint32_t bound = ((const uint32_t *) table)[1];
57 uint32_t lookup1 = ((const uint32_t *) table)[5 + index1];
60 uint32_t shift2 = ((const uint32_t *) table)[2];
61 uint32_t mask2 = ((const uint32_t *) table)[3];
62 uint32_t index2 = (wc >> shift2) & mask2;
63 uint32_t lookup2 = ((const uint32_t *)(table + lookup1))[index2];
66 uint32_t mask3 = ((const uint32_t *) table)[4];
67 uint32_t index3 = (wc >> 5) & mask3;
68 uint32_t lookup3 = ((const uint32_t *)(table + lookup2))[index3];
70 return (lookup3 >> (wc & 0x1f)) & 1;
77 /* Byte tables are similar to bit tables, except that the addressing
78 unit is a single byte, and no 5 bits are used as a word index. */
81 wcwidth_table_lookup (const char *table, uint32_t wc)
83 uint32_t shift1 = ((const uint32_t *) table)[0];
84 uint32_t index1 = wc >> shift1;
85 uint32_t bound = ((const uint32_t *) table)[1];
88 uint32_t lookup1 = ((const uint32_t *) table)[5 + index1];
91 uint32_t shift2 = ((const uint32_t *) table)[2];
92 uint32_t mask2 = ((const uint32_t *) table)[3];
93 uint32_t index2 = (wc >> shift2) & mask2;
94 uint32_t lookup2 = ((const uint32_t *)(table + lookup1))[index2];
97 uint32_t mask3 = ((const uint32_t *) table)[4];
98 uint32_t index3 = wc & mask3;
99 uint8_t lookup3 = ((const uint8_t *)(table + lookup2))[index3];
108 /* Mapping tables are similar to bit tables, except that the
109 addressing unit is a single signed 32-bit word, containing the
110 difference between the desired result and the argument, and no 5
111 bits are used as a word index. */
113 static __inline uint32_t
114 wctrans_table_lookup (const char *table, uint32_t wc)
116 uint32_t shift1 = ((const uint32_t *) table)[0];
117 uint32_t index1 = wc >> shift1;
118 uint32_t bound = ((const uint32_t *) table)[1];
121 uint32_t lookup1 = ((const uint32_t *) table)[5 + index1];
124 uint32_t shift2 = ((const uint32_t *) table)[2];
125 uint32_t mask2 = ((const uint32_t *) table)[3];
126 uint32_t index2 = (wc >> shift2) & mask2;
127 uint32_t lookup2 = ((const uint32_t *)(table + lookup1))[index2];
130 uint32_t mask3 = ((const uint32_t *) table)[4];
131 uint32_t index3 = wc & mask3;
132 int32_t lookup3 = ((const int32_t *)(table + lookup2))[index3];