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Diffstat (limited to 'wctype/wchar-lookup.h')
| -rw-r--r-- | wctype/wchar-lookup.h | 139 |
1 files changed, 139 insertions, 0 deletions
diff --git a/wctype/wchar-lookup.h b/wctype/wchar-lookup.h new file mode 100644 index 0000000000..1d08492035 --- /dev/null +++ b/wctype/wchar-lookup.h @@ -0,0 +1,139 @@ +/* Copyright (C) 2000 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 Library General Public License as + published by the Free Software Foundation; either version 2 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 + Library General Public License for more details. + + You should have received a copy of the GNU Library General Public + License along with the GNU C Library; see the file COPYING.LIB. If not, + write to the Free Software Foundation, Inc., 59 Temple Place - Suite 330, + Boston, MA 02111-1307, USA. */ + +/* 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 block 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 +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 +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 +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; +} |