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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. | |
4 | ||
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. | |
9 | ||
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. | |
14 | ||
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. */ | |
19 | ||
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 | |
23 | data. */ | |
24 | ||
25 | /* Bit tables are accessed by cutting wc in four blocks of bits: | |
26 | - the high 32-q-p bits, | |
27 | - the next q bits, | |
28 | - the next p bits, | |
29 | - the next 5 bits. | |
30 | ||
31 | +------------------+-----+-----+-----+ | |
32 | wc = + 32-q-p-5 | q | p | 5 | | |
33 | +------------------+-----+-----+-----+ | |
34 | ||
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. | |
37 | ||
38 | The table contains the following uint32_t words: | |
39 | - q+p+5, | |
40 | - s = upper exclusive bound for wc >> (q+p+5), | |
41 | - p+5, | |
42 | - 2^q-1, | |
43 | - 2^p-1, | |
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. | |
47 | */ | |
48 | ||
49 | static __inline int | |
50 | wctype_table_lookup (const char *table, uint32_t wc) | |
51 | { | |
52 | uint32_t shift1 = ((const uint32_t *) table)[0]; | |
53 | uint32_t index1 = wc >> shift1; | |
54 | uint32_t bound = ((const uint32_t *) table)[1]; | |
55 | if (index1 < bound) | |
56 | { | |
57 | uint32_t lookup1 = ((const uint32_t *) table)[5 + index1]; | |
58 | if (lookup1 != 0) | |
59 | { | |
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]; | |
64 | if (lookup2 != 0) | |
65 | { | |
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]; | |
69 | ||
70 | return (lookup3 >> (wc & 0x1f)) & 1; | |
71 | } | |
72 | } | |
73 | } | |
74 | return 0; | |
75 | } | |
76 | ||
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. */ | |
79 | ||
80 | static __inline int | |
81 | wcwidth_table_lookup (const char *table, uint32_t wc) | |
82 | { | |
83 | uint32_t shift1 = ((const uint32_t *) table)[0]; | |
84 | uint32_t index1 = wc >> shift1; | |
85 | uint32_t bound = ((const uint32_t *) table)[1]; | |
86 | if (index1 < bound) | |
87 | { | |
88 | uint32_t lookup1 = ((const uint32_t *) table)[5 + index1]; | |
89 | if (lookup1 != 0) | |
90 | { | |
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]; | |
95 | if (lookup2 != 0) | |
96 | { | |
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]; | |
100 | ||
101 | return lookup3; | |
102 | } | |
103 | } | |
104 | } | |
105 | return 0xff; | |
106 | } | |
107 | ||
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. */ | |
112 | ||
113 | static __inline uint32_t | |
114 | wctrans_table_lookup (const char *table, uint32_t wc) | |
115 | { | |
116 | uint32_t shift1 = ((const uint32_t *) table)[0]; | |
117 | uint32_t index1 = wc >> shift1; | |
118 | uint32_t bound = ((const uint32_t *) table)[1]; | |
119 | if (index1 < bound) | |
120 | { | |
121 | uint32_t lookup1 = ((const uint32_t *) table)[5 + index1]; | |
122 | if (lookup1 != 0) | |
123 | { | |
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]; | |
128 | if (lookup2 != 0) | |
129 | { | |
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]; | |
133 | ||
134 | return wc + lookup3; | |
135 | } | |
136 | } | |
137 | } | |
138 | return wc; | |
139 | } |