1/* Copyright (C) 2000-2021 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 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.
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 Lesser General Public License for more details.
14
15 You should have received a copy of the GNU Lesser General Public
16 License along with the GNU C Library; if not, see
17 <https://www.gnu.org/licenses/>. */
18
19#include <stdint.h>
20
21/* Tables indexed by a wide character are compressed through the use
22 of a multi-level lookup. The compression effect comes from blocks
23 that don't need particular data and from blocks that can share their
24 data. */
25
26/* Bit tables are accessed by cutting wc in four blocks of bits:
27 - the high 32-q-p bits,
28 - the next q bits,
29 - the next p bits,
30 - the next 5 bits.
31
32 +------------------+-----+-----+-----+
33 wc = + 32-q-p-5 | q | p | 5 |
34 +------------------+-----+-----+-----+
35
36 p and q are variable. For 16-bit Unicode it is sufficient to
37 choose p and q such that q+p+5 <= 16.
38
39 The table contains the following uint32_t words:
40 - q+p+5,
41 - s = upper exclusive bound for wc >> (q+p+5),
42 - p+5,
43 - 2^q-1,
44 - 2^p-1,
45 - 1st-level table: s offsets, pointing into the 2nd-level table,
46 - 2nd-level table: k*2^q offsets, pointing into the 3rd-level table,
47 - 3rd-level table: j*2^p words, each containing 32 bits of data.
48*/
49
50static __inline int
51__attribute ((always_inline))
52wctype_table_lookup (const char *table, uint32_t wc)
53{
54 uint32_t shift1 = ((const uint32_t *) table)[0];
55 uint32_t index1 = wc >> shift1;
56 uint32_t bound = ((const uint32_t *) table)[1];
57 if (index1 < bound)
58 {
59 uint32_t lookup1 = ((const uint32_t *) table)[5 + index1];
60 if (lookup1 != 0)
61 {
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];
66 if (lookup2 != 0)
67 {
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];
71
72 return (lookup3 >> (wc & 0x1f)) & 1;
73 }
74 }
75 }
76 return 0;
77}
78
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. */
81
82static __inline int
83__attribute ((always_inline))
84wcwidth_table_lookup (const char *table, uint32_t wc)
85{
86 uint32_t shift1 = ((const uint32_t *) table)[0];
87 uint32_t index1 = wc >> shift1;
88 uint32_t bound = ((const uint32_t *) table)[1];
89 if (index1 < bound)
90 {
91 uint32_t lookup1 = ((const uint32_t *) table)[5 + index1];
92 if (lookup1 != 0)
93 {
94 uint32_t shift2 = ((const uint32_t *) table)[2];
95 uint32_t mask2 = ((const uint32_t *) table)[3];
96 uint32_t index2 = (wc >> shift2) & mask2;
97 uint32_t lookup2 = ((const uint32_t *)(table + lookup1))[index2];
98 if (lookup2 != 0)
99 {
100 uint32_t mask3 = ((const uint32_t *) table)[4];
101 uint32_t index3 = wc & mask3;
102 uint8_t lookup3 = ((const uint8_t *)(table + lookup2))[index3];
103
104 return lookup3;
105 }
106 }
107 }
108 return 0xff;
109}
110
111/* Mapping tables are similar to bit tables, except that the
112 addressing unit is a single signed 32-bit word, containing the
113 difference between the desired result and the argument, and no 5
114 bits are used as a word index. */
115
116static __inline uint32_t
117__attribute ((always_inline))
118wctrans_table_lookup (const char *table, uint32_t wc)
119{
120 uint32_t shift1 = ((const uint32_t *) table)[0];
121 uint32_t index1 = wc >> shift1;
122 uint32_t bound = ((const uint32_t *) table)[1];
123 if (index1 < bound)
124 {
125 uint32_t lookup1 = ((const uint32_t *) table)[5 + index1];
126 if (lookup1 != 0)
127 {
128 uint32_t shift2 = ((const uint32_t *) table)[2];
129 uint32_t mask2 = ((const uint32_t *) table)[3];
130 uint32_t index2 = (wc >> shift2) & mask2;
131 uint32_t lookup2 = ((const uint32_t *)(table + lookup1))[index2];
132 if (lookup2 != 0)
133 {
134 uint32_t mask3 = ((const uint32_t *) table)[4];
135 uint32_t index3 = wc & mask3;
136 int32_t lookup3 = ((const int32_t *)(table + lookup2))[index3];
137
138 return wc + lookup3;
139 }
140 }
141 }
142 return wc;
143}
144