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1 | /* Copyright (C) 2000-2024 Free Software Foundation, Inc. | |
2 | This file is part of the GNU C Library. | |
3 | ||
4 | The GNU C Library is free software; you can redistribute it and/or | |
5 | modify it under the terms of the GNU Lesser General Public | |
6 | License as published by the Free Software Foundation; either | |
7 | version 2.1 of the License, or (at your option) any later version. | |
8 | ||
9 | The GNU C Library is distributed in the hope that it will be useful, | |
10 | but WITHOUT ANY WARRANTY; without even the implied warranty of | |
11 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU | |
12 | Lesser General Public License for more details. | |
13 | ||
14 | You should have received a copy of the GNU Lesser General Public | |
15 | License along with the GNU C Library; if not, see | |
16 | <https://www.gnu.org/licenses/>. */ | |
17 | ||
18 | #include <stdint.h> | |
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 blocks 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 | __attribute ((always_inline)) | |
51 | wctype_table_lookup (const char *table, uint32_t wc) | |
52 | { | |
53 | uint32_t shift1 = ((const uint32_t *) table)[0]; | |
54 | uint32_t index1 = wc >> shift1; | |
55 | uint32_t bound = ((const uint32_t *) table)[1]; | |
56 | if (index1 < bound) | |
57 | { | |
58 | uint32_t lookup1 = ((const uint32_t *) table)[5 + index1]; | |
59 | if (lookup1 != 0) | |
60 | { | |
61 | uint32_t shift2 = ((const uint32_t *) table)[2]; | |
62 | uint32_t mask2 = ((const uint32_t *) table)[3]; | |
63 | uint32_t index2 = (wc >> shift2) & mask2; | |
64 | uint32_t lookup2 = ((const uint32_t *)(table + lookup1))[index2]; | |
65 | if (lookup2 != 0) | |
66 | { | |
67 | uint32_t mask3 = ((const uint32_t *) table)[4]; | |
68 | uint32_t index3 = (wc >> 5) & mask3; | |
69 | uint32_t lookup3 = ((const uint32_t *)(table + lookup2))[index3]; | |
70 | ||
71 | return (lookup3 >> (wc & 0x1f)) & 1; | |
72 | } | |
73 | } | |
74 | } | |
75 | return 0; | |
76 | } | |
77 | ||
78 | /* Byte tables are similar to bit tables, except that the addressing | |
79 | unit is a single byte, and no 5 bits are used as a word index. */ | |
80 | ||
81 | static __inline int | |
82 | __attribute ((always_inline)) | |
83 | wcwidth_table_lookup (const char *table, uint32_t wc) | |
84 | { | |
85 | uint32_t shift1 = ((const uint32_t *) table)[0]; | |
86 | uint32_t index1 = wc >> shift1; | |
87 | uint32_t bound = ((const uint32_t *) table)[1]; | |
88 | if (index1 < bound) | |
89 | { | |
90 | uint32_t lookup1 = ((const uint32_t *) table)[5 + index1]; | |
91 | if (lookup1 != 0) | |
92 | { | |
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]; | |
97 | if (lookup2 != 0) | |
98 | { | |
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]; | |
102 | ||
103 | return lookup3; | |
104 | } | |
105 | } | |
106 | } | |
107 | return 0xff; | |
108 | } | |
109 | ||
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. */ | |
114 | ||
115 | static __inline uint32_t | |
116 | __attribute ((always_inline)) | |
117 | wctrans_table_lookup (const char *table, uint32_t wc) | |
118 | { | |
119 | uint32_t shift1 = ((const uint32_t *) table)[0]; | |
120 | uint32_t index1 = wc >> shift1; | |
121 | uint32_t bound = ((const uint32_t *) table)[1]; | |
122 | if (index1 < bound) | |
123 | { | |
124 | uint32_t lookup1 = ((const uint32_t *) table)[5 + index1]; | |
125 | if (lookup1 != 0) | |
126 | { | |
127 | uint32_t shift2 = ((const uint32_t *) table)[2]; | |
128 | uint32_t mask2 = ((const uint32_t *) table)[3]; | |
129 | uint32_t index2 = (wc >> shift2) & mask2; | |
130 | uint32_t lookup2 = ((const uint32_t *)(table + lookup1))[index2]; | |
131 | if (lookup2 != 0) | |
132 | { | |
133 | uint32_t mask3 = ((const uint32_t *) table)[4]; | |
134 | uint32_t index3 = wc & mask3; | |
135 | int32_t lookup3 = ((const int32_t *)(table + lookup2))[index3]; | |
136 | ||
137 | return wc + lookup3; | |
138 | } | |
139 | } | |
140 | } | |
141 | return wc; | |
142 | } |