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glibc/wctype/wchar-lookup.h
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/* Copyright (C) 2000-2016 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; | |
} |