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/* 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;
}
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