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 Lesser General Public
7 License as published by the Free Software Foundation; either
8 version 2.1 of the 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 Lesser General Public License for more details.
15 You should have received a copy of the GNU Lesser General Public
16 License along with the GNU C Library; if not, write to the Free
17 Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
22 /* Tables indexed by a wide character are compressed through the use
23 of a multi-level lookup. The compression effect comes from blocks
24 that don't need particular data and from blocks that can share their
27 /* Bit tables are accessed by cutting wc in four blocks of bits:
28 - the high 32-q-p bits,
33 +------------------+-----+-----+-----+
34 wc = + 32-q-p-5 | q | p | 5 |
35 +------------------+-----+-----+-----+
37 p and q are variable. For 16-bit Unicode it is sufficient to
38 choose p and q such that q+p+5 <= 16.
40 The table contains the following uint32_t words:
42 - s = upper exclusive bound for wc >> (q+p+5),
46 - 1st-level table: s offsets, pointing into the 2nd-level table,
47 - 2nd-level table: k*2^q offsets, pointing into the 3rd-level table,
48 - 3rd-level table: j*2^p words, each containing 32 bits of data.
52 wctype_table_lookup (const char *table, uint32_t wc)
54 uint32_t shift1 = ((const uint32_t *) table)[0];
55 uint32_t index1 = wc >> shift1;
56 uint32_t bound = ((const uint32_t *) table)[1];
59 uint32_t lookup1 = ((const uint32_t *) table)[5 + index1];
62 uint32_t shift2 = ((const uint32_t *) table)[2];
63 uint32_t mask2 = ((const uint32_t *) table)[3];
64 uint32_t index2 = (wc >> shift2) & mask2;
65 uint32_t lookup2 = ((const uint32_t *)(table + lookup1))[index2];
68 uint32_t mask3 = ((const uint32_t *) table)[4];
69 uint32_t index3 = (wc >> 5) & mask3;
70 uint32_t lookup3 = ((const uint32_t *)(table + lookup2))[index3];
72 return (lookup3 >> (wc & 0x1f)) & 1;
79 /* Byte tables are similar to bit tables, except that the addressing
80 unit is a single byte, and no 5 bits are used as a word index. */
83 wcwidth_table_lookup (const char *table, uint32_t wc)
85 uint32_t shift1 = ((const uint32_t *) table)[0];
86 uint32_t index1 = wc >> shift1;
87 uint32_t bound = ((const uint32_t *) table)[1];
90 uint32_t lookup1 = ((const uint32_t *) table)[5 + index1];
93 uint32_t shift2 = ((const uint32_t *) table)[2];
94 uint32_t mask2 = ((const uint32_t *) table)[3];
95 uint32_t index2 = (wc >> shift2) & mask2;
96 uint32_t lookup2 = ((const uint32_t *)(table + lookup1))[index2];
99 uint32_t mask3 = ((const uint32_t *) table)[4];
100 uint32_t index3 = wc & mask3;
101 uint8_t lookup3 = ((const uint8_t *)(table + lookup2))[index3];
110 /* Mapping tables are similar to bit tables, except that the
111 addressing unit is a single signed 32-bit word, containing the
112 difference between the desired result and the argument, and no 5
113 bits are used as a word index. */
115 static __inline uint32_t
116 wctrans_table_lookup (const char *table, uint32_t wc)
118 uint32_t shift1 = ((const uint32_t *) table)[0];
119 uint32_t index1 = wc >> shift1;
120 uint32_t bound = ((const uint32_t *) table)[1];
123 uint32_t lookup1 = ((const uint32_t *) table)[5 + index1];
126 uint32_t shift2 = ((const uint32_t *) table)[2];
127 uint32_t mask2 = ((const uint32_t *) table)[3];
128 uint32_t index2 = (wc >> shift2) & mask2;
129 uint32_t lookup2 = ((const uint32_t *)(table + lookup1))[index2];
132 uint32_t mask3 = ((const uint32_t *) table)[4];
133 uint32_t index3 = wc & mask3;
134 int32_t lookup3 = ((const int32_t *)(table + lookup2))[index3];