File: wchar-lookup.h

package info (click to toggle)
glibc 2.28-8
  • links: PTS, VCS
  • area: main
  • in suites: buster, experimental, sid
  • size: 271,788 kB
  • sloc: ansic: 1,008,637; asm: 259,607; makefile: 11,271; sh: 10,477; python: 6,910; cpp: 4,992; perl: 2,258; awk: 2,005; yacc: 290; pascal: 182; sed: 73
file content (143 lines) | stat: -rw-r--r-- 4,751 bytes parent folder | download | duplicates (4)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
/* Copyright (C) 2000-2018 Free Software Foundation, Inc.
   This file is part of the GNU C Library.
   Contributed by Bruno Haible <haible@clisp.cons.org>, 2000.

   The GNU C Library is free software; you can redistribute it and/or
   modify it under the terms of the GNU Lesser General Public
   License as published by the Free Software Foundation; either
   version 2.1 of the License, or (at your option) any later version.

   The GNU C Library is distributed in the hope that it will be useful,
   but WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
   Lesser General Public License for more details.

   You should have received a copy of the GNU Lesser General Public
   License along with the GNU C Library; if not, see
   <http://www.gnu.org/licenses/>.  */

#include <stdint.h>

/* Tables indexed by a wide character are compressed through the use
   of a multi-level lookup.  The compression effect comes from blocks
   that don't need particular data and from blocks that can share their
   data.  */

/* Bit tables are accessed by cutting wc in four blocks of bits:
   - the high 32-q-p bits,
   - the next q bits,
   - the next p bits,
   - the next 5 bits.

	    +------------------+-----+-----+-----+
     wc  =  +     32-q-p-5     |  q  |  p  |  5  |
	    +------------------+-----+-----+-----+

   p and q are variable.  For 16-bit Unicode it is sufficient to
   choose p and q such that q+p+5 <= 16.

   The table contains the following uint32_t words:
   - q+p+5,
   - s = upper exclusive bound for wc >> (q+p+5),
   - p+5,
   - 2^q-1,
   - 2^p-1,
   - 1st-level table: s offsets, pointing into the 2nd-level table,
   - 2nd-level table: k*2^q offsets, pointing into the 3rd-level table,
   - 3rd-level table: j*2^p words, each containing 32 bits of data.
*/

static __inline int
__attribute ((always_inline))
wctype_table_lookup (const char *table, uint32_t wc)
{
  uint32_t shift1 = ((const uint32_t *) table)[0];
  uint32_t index1 = wc >> shift1;
  uint32_t bound = ((const uint32_t *) table)[1];
  if (index1 < bound)
    {
      uint32_t lookup1 = ((const uint32_t *) table)[5 + index1];
      if (lookup1 != 0)
	{
	  uint32_t shift2 = ((const uint32_t *) table)[2];
	  uint32_t mask2 = ((const uint32_t *) table)[3];
	  uint32_t index2 = (wc >> shift2) & mask2;
	  uint32_t lookup2 = ((const uint32_t *)(table + lookup1))[index2];
	  if (lookup2 != 0)
	    {
	      uint32_t mask3 = ((const uint32_t *) table)[4];
	      uint32_t index3 = (wc >> 5) & mask3;
	      uint32_t lookup3 = ((const uint32_t *)(table + lookup2))[index3];

	      return (lookup3 >> (wc & 0x1f)) & 1;
	    }
	}
    }
  return 0;
}

/* Byte tables are similar to bit tables, except that the addressing
   unit is a single byte, and no 5 bits are used as a word index.  */

static __inline int
__attribute ((always_inline))
wcwidth_table_lookup (const char *table, uint32_t wc)
{
  uint32_t shift1 = ((const uint32_t *) table)[0];
  uint32_t index1 = wc >> shift1;
  uint32_t bound = ((const uint32_t *) table)[1];
  if (index1 < bound)
    {
      uint32_t lookup1 = ((const uint32_t *) table)[5 + index1];
      if (lookup1 != 0)
	{
	  uint32_t shift2 = ((const uint32_t *) table)[2];
	  uint32_t mask2 = ((const uint32_t *) table)[3];
	  uint32_t index2 = (wc >> shift2) & mask2;
	  uint32_t lookup2 = ((const uint32_t *)(table + lookup1))[index2];
	  if (lookup2 != 0)
	    {
	      uint32_t mask3 = ((const uint32_t *) table)[4];
	      uint32_t index3 = wc & mask3;
	      uint8_t lookup3 = ((const uint8_t *)(table + lookup2))[index3];

	      return lookup3;
	    }
	}
    }
  return 0xff;
}

/* Mapping tables are similar to bit tables, except that the
   addressing unit is a single signed 32-bit word, containing the
   difference between the desired result and the argument, and no 5
   bits are used as a word index.  */

static __inline uint32_t
__attribute ((always_inline))
wctrans_table_lookup (const char *table, uint32_t wc)
{
  uint32_t shift1 = ((const uint32_t *) table)[0];
  uint32_t index1 = wc >> shift1;
  uint32_t bound = ((const uint32_t *) table)[1];
  if (index1 < bound)
    {
      uint32_t lookup1 = ((const uint32_t *) table)[5 + index1];
      if (lookup1 != 0)
	{
	  uint32_t shift2 = ((const uint32_t *) table)[2];
	  uint32_t mask2 = ((const uint32_t *) table)[3];
	  uint32_t index2 = (wc >> shift2) & mask2;
	  uint32_t lookup2 = ((const uint32_t *)(table + lookup1))[index2];
	  if (lookup2 != 0)
	    {
	      uint32_t mask3 = ((const uint32_t *) table)[4];
	      uint32_t index3 = wc & mask3;
	      int32_t lookup3 = ((const int32_t *)(table + lookup2))[index3];

	      return wc + lookup3;
	    }
	}
    }
  return wc;
}