452 lines
17 KiB
C
452 lines
17 KiB
C
/*
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******************************************************************************
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*
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* Copyright (C) 2003, International Business Machines
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* Corporation and others. All Rights Reserved.
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*
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******************************************************************************
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* file name: ucnv_ext.h
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* encoding: US-ASCII
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* tab size: 8 (not used)
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* indentation:4
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*
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* created on: 2003jun13
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* created by: Markus W. Scherer
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*
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* Conversion extensions
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*/
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#ifndef __UCNV_EXT_H__
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#define __UCNV_EXT_H__
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#include "unicode/utypes.h"
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#include "unicode/ucnv.h"
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/*
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* See icuhtml/design/conversion/conversion_extensions.html
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*
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* Conversion extensions serve two purposes:
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* 1. They support m:n mappings.
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* 2. They support extension-only conversion files that are used together
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* with the regular conversion data in base files.
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*
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* A base file may contain an extension table (explicitly requested or
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* implicitly generated for m:n mappings), but its extension table is not
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* used when an extension-only file is used.
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*
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* It is an error if a base file contains any regular (not extension) mapping
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* from the same sequence as a mapping in the extension file
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* because the base mapping would hide the extension mapping.
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*
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*
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* Data for conversion extensions:
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*
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* One set of data structures per conversion direction (to/from Unicode).
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* The data structures are sorted by input units to allow for binary search.
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* Input sequences of more than one unit are handled like contraction tables
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* in collation:
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* The lookup value of a unit points to another table that is to be searched
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* for the next unit, recursively.
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*
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* For conversion from Unicode, the initial code point is looked up in
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* a 3-stage trie for speed,
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* with an additional table of unique results to save space.
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*
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* Long output strings are stored in separate arrays, with length and index
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* in the lookup tables.
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* Output results also include a flag distinguishing roundtrip from
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* (reverse) fallback mappings.
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*
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* Input Unicode strings must not begin or end with unpaired surrogates
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* to avoid problems with matches on parts of surrogate pairs.
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*
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* Mappings from multiple characters (code points or codepage state
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* table sequences) must be searched preferring the longest match.
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* For this to work and be efficient, the variable-width table must contain
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* all mappings that contain prefixes of the multiple characters.
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* If an extension table is built on top of a base table in another file
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* and a base table entry is a prefix of a multi-character mapping, then
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* this is an error.
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*
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*
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* Implementation note:
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*
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* Currently, the parser and several checks in the code limit the number
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* of UChars or bytes in a mapping to
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* UCNV_EXT_MAX_UCHARS and UCNV_EXT_MAX_BYTES, respectively,
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* which are output value limits in the data structure.
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*
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* For input, this is not strictly necessary - it is a hard limit only for the
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* buffers in UConverter that are used to store partial matches.
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*
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* Input sequences could otherwise be arbitrarily long if partial matches
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* need not be stored (i.e., if a sequence does not span several buffers with too
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* many units before the last buffer), although then results would differ
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* depending on whether partial matches exceed the limits or not,
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* which depends on the pattern of buffer sizes.
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*
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*
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* Data structure:
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*
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* int32_t indexes[>=32];
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*
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* Array of indexes and lengths etc. The length of the array is at least 32.
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* The actual length is stored in indexes[0] to be forward compatible.
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*
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* Each index to another array is the number of bytes from indexes[].
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* Each length of an array is the number of array base units in that array.
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*
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* Some of the structures may not be present, in which case their indexes
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* and lengths are 0.
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*
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* Usage of indexes[i]:
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* [0] length of indexes[]
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*
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* // to Unicode table
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* [1] index of toUTable[] (array of uint32_t)
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* [2] length of toUTable[]
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* [3] index of toUUChars[] (array of UChar)
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* [4] length of toUUChars[]
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*
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* // from Unicode table, not for the initial code point
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* [5] index of fromUTableUChars[] (array of UChar)
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* [6] index of fromUTableValues[] (array of uint32_t)
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* [7] length of fromUTableUChars[] and fromUTableValues[]
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* [8] index of fromUBytes[] (array of char)
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* [9] length of fromUBytes[]
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*
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* // from Unicode trie for initial-code point lookup
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* [10] index of fromUStage12[] (combined array of uint16_t for stages 1 & 2)
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* [11] length of stage 1 portion of fromUStage12[]
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* [12] length of fromUStage12[]
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* [13] index of fromUStage3[] (array of uint16_t indexes into fromUStage3b[])
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* [14] length of fromUStage3[]
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* [15] index of fromUStage3b[] (array of uint32_t like fromUTableValues[])
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* [16] length of fromUStage3b[]
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*
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* [17] Bit field containing numbers of bytes:
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* 31..24 reserved, 0
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* 23..16 maximum input bytes
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* 15.. 8 maximum output bytes
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* 7.. 0 maximum bytes per UChar
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*
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* [18] Bit field containing numbers of UChars:
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* 31..24 reserved, 0
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* 23..16 maximum input UChars
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* 15.. 8 maximum output UChars
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* 7.. 0 maximum UChars per byte
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*
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* [19]..[30] reserved, 0
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* [31] number of bytes for the entire extension structure
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* [>31] reserved; there are indexes[0] indexes
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*
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*
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* uint32_t toUTable[];
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*
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* Array of byte/value pairs for lookups for toUnicode conversion.
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* The array is partitioned into sections like collation contraction tables.
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* Each section contains one word with the number of following words and
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* a default value for when the lookup in this section yields no match.
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*
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* A section is sorted in ascending order of input bytes,
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* allowing for fast linear or binary searches.
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* The builder may store entries for a contiguous range of byte values
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* (compare difference between the first and last one with count),
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* which then allows for direct array access.
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* The builder should always do this for the initial table section.
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*
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* Entries may have 0 values, see below.
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* No two entries in a section have the same byte values.
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*
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* Each uint32_t contains an input byte value in bits 31..24 and the
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* corresponding lookup value in bits 23..0.
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* Interpret the value as follows:
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* if(value==0) {
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* no match, see below
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* } else if(value<0x1f0000) {
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* partial match - use value as index to the next toUTable section
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* and match the next unit; (value indexes toUTable[value])
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* } else {
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* if(bit 23 set) {
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* roundtrip;
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* } else {
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* fallback;
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* }
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* unset value bit 23;
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* if(value<=0x2fffff) {
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* (value-0x1f0000) is a code point; (BMP: value<=0x1fffff)
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* } else {
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* bits 17..0 (value&0x3ffff) is an index to
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* the result UChars in toUUChars[]; (0 indexes toUUChars[0])
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* length of the result=((value>>18)-12); (length=0..19)
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* }
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* }
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*
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* The first word in a section contains the number of following words in the
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* input byte position (bits 31..24, number=1..0xff).
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* The value of the initial word is used when the current byte is not found
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* in this section.
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* If the value is not 0, then it represents a result as above.
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* If the value is 0, then the search has to return a shorter match with an
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* earlier default value as the result, or result in "unmappable" even for the
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* initial bytes.
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* If the value is 0 for the initial toUTable entry, then the initial byte
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* does not start any mapping input.
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*
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*
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* UChar toUUChars[];
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*
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* Contains toUnicode mapping results, stored as sequences of UChars.
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* Indexes and lengths stored in the toUTable[].
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*
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*
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* UChar fromUTableUChars[];
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* uint32_t fromUTableValues[];
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*
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* The fromUTable is split into two arrays, but works otherwise much like
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* the toUTable. The array is partitioned into sections like collation
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* contraction tables and toUTable.
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* A row in the table consists of same-index entries in fromUTableUChars[]
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* and fromUTableValues[].
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*
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* Interpret a value as follows:
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* if(value==0) {
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* no match, see below
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* } else if(value<=0xffffff) { (bits 31..24 are 0)
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* partial match - use value as index to the next fromUTable section
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* and match the next unit; (value indexes fromUTable[value])
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* } else {
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* if(value==0x80000001) {
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* return no mapping, but request for <subchar1>;
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* }
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* if(bit 31 set) {
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* roundtrip;
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* } else {
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* fallback;
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* }
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* // bits 30..29 reserved, 0
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* length=(value>>24)&0x1f; (bits 28..24)
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* if(length==1..3) {
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* bits 23..0 contain 1..3 bytes, padded with 00s on the left;
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* } else {
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* bits 23..0 (value&0xffffff) is an index to
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* the result bytes in fromUBytes[]; (0 indexes fromUBytes[0])
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* }
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* }
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*
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* The first pair in a section contains the number of following pairs in the
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* UChar position (16 bits, number=1..0xffff).
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* The value of the initial pair is used when the current UChar is not found
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* in this section.
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* If the value is not 0, then it represents a result as above.
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* If the value is 0, then the search has to return a shorter match with an
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* earlier default value as the result, or result in "unmappable" even for the
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* initial UChars.
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*
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* If the from Unicode trie is present, then the from Unicode search tables
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* are not used for initial code points.
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* In this case, the first entries (index 0) in the tables are not used
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* (reserved, set to 0) because a value of 0 is used in trie results
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* to indicate no mapping.
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*
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*
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* uint16_t fromUStage12[];
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*
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* Stages 1 & 2 of a trie that maps an initial code point.
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* Indexes in stage 1 are all offset by the length of stage 1 so that the
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* same array pointer can be used for both stages.
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* If (c>>10)>=(length of stage 1) then c does not start any mapping.
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* Same bit distribution as for regular conversion tries.
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*
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*
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* uint16_t fromUStage3[];
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* uint32_t fromUStage3b[];
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*
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* Stage 3 of the trie. The first array simply contains indexes to the second,
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* which contains words in the same format as fromUTableValues[].
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* Use a stage 3 granularity of 4, which allows for 256k stage 3 entries,
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* and 16-bit entries in stage 3 allow for 64k stage 3b entries.
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* The stage 3 granularity means that the stage 2 entry needs to be left-shifted.
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*
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* Two arrays are used because it is expected that more than half of the stage 3
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* entries will be zero. The 16-bit index stage 3 array saves space even
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* considering storing a total of 6 bytes per non-zero entry in both arrays
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* together.
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* Using a stage 3 granularity of >1 diminishes the compactability in that stage
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* but provides a larger effective addressing space in stage 2.
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* All but the final result stage use 16-bit entries to save space.
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*
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* fromUStage3b[] contains a zero for "no mapping" at its index 0,
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* and may contain UCNV_EXT_FROM_U_SUBCHAR1 at index 1 for "<subchar1> SUB mapping"
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* (i.e., "no mapping" with preference for <subchar1> rather than <subchar>),
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* and all other items are unique non-zero results.
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*
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* The default value of a fromUTableValues[] section that is referenced
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* _directly_ from a fromUStage3b[] item may also be UCNV_EXT_FROM_U_SUBCHAR1,
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* but this value must not occur anywhere else in fromUTableValues[]
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* because "no mapping" is always a property of a single code point,
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* never of multiple.
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*
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*
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* char fromUBytes[];
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*
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* Contains fromUnicode mapping results, stored as sequences of chars.
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* Indexes and lengths stored in the fromUTableValues[].
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*/
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enum {
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UCNV_EXT_INDEXES_LENGTH, /* 0 */
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UCNV_EXT_TO_U_INDEX, /* 1 */
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UCNV_EXT_TO_U_LENGTH,
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UCNV_EXT_TO_U_UCHARS_INDEX,
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UCNV_EXT_TO_U_UCHARS_LENGTH,
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UCNV_EXT_FROM_U_UCHARS_INDEX, /* 5 */
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UCNV_EXT_FROM_U_VALUES_INDEX,
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UCNV_EXT_FROM_U_LENGTH,
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UCNV_EXT_FROM_U_BYTES_INDEX,
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UCNV_EXT_FROM_U_BYTES_LENGTH,
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UCNV_EXT_FROM_U_STAGE_12_INDEX, /* 10 */
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UCNV_EXT_FROM_U_STAGE_1_LENGTH,
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UCNV_EXT_FROM_U_STAGE_12_LENGTH,
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UCNV_EXT_FROM_U_STAGE_3_INDEX,
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UCNV_EXT_FROM_U_STAGE_3_LENGTH,
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UCNV_EXT_FROM_U_STAGE_3B_INDEX,
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UCNV_EXT_FROM_U_STAGE_3B_LENGTH,
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UCNV_EXT_COUNT_BYTES, /* 17 */
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UCNV_EXT_COUNT_UCHARS,
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UCNV_EXT_RESERVED_INDEX, /* 19, moves with additional indexes */
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UCNV_EXT_SIZE=31,
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UCNV_EXT_INDEXES_MIN_LENGTH=32
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};
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/* get the pointer to an extension array from indexes[index] */
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#define UCNV_EXT_ARRAY(indexes, index, itemType) \
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((const itemType *)((const char *)(indexes)+(indexes)[index]))
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#define UCNV_GET_MAX_BYTES_PER_UCHAR(indexes) \
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((indexes)[UCNV_EXT_COUNT_BYTES]&0xff)
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/* internal API ------------------------------------------------------------- */
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U_CFUNC UBool
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ucnv_extInitialMatchToU(UConverter *cnv, const int32_t *cx,
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int32_t firstLength,
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const char **src, const char *srcLimit,
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UChar **target, const UChar *targetLimit,
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int32_t **offsets, int32_t srcIndex,
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UBool flush,
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UErrorCode *pErrorCode);
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U_CFUNC UChar32
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ucnv_extSimpleMatchToU(const int32_t *cx,
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const char *source, int32_t length,
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UBool useFallback);
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U_CFUNC void
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ucnv_extContinueMatchToU(UConverter *cnv,
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UConverterToUnicodeArgs *pArgs, int32_t srcIndex,
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UErrorCode *pErrorCode);
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U_CFUNC UBool
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ucnv_extInitialMatchFromU(UConverter *cnv, const int32_t *cx,
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UChar32 cp,
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const UChar **src, const UChar *srcLimit,
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char **target, const char *targetLimit,
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int32_t **offsets, int32_t srcIndex,
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UBool flush,
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UErrorCode *pErrorCode);
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U_CFUNC int32_t
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ucnv_extSimpleMatchFromU(const int32_t *cx,
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UChar32 cp, uint32_t *pValue,
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UBool useFallback);
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U_CFUNC void
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ucnv_extContinueMatchFromU(UConverter *cnv,
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UConverterFromUnicodeArgs *pArgs, int32_t srcIndex,
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UErrorCode *pErrorCode);
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U_CFUNC void
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ucnv_extGetUnicodeSet(const UConverter *cnv,
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USet *set,
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UConverterUnicodeSet which,
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UErrorCode *pErrorCode);
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/* toUnicode helpers -------------------------------------------------------- */
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#define UCNV_EXT_TO_U_BYTE_SHIFT 24
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#define UCNV_EXT_TO_U_VALUE_MASK 0xffffff
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#define UCNV_EXT_TO_U_MIN_CODE_POINT 0x1f0000
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#define UCNV_EXT_TO_U_MAX_CODE_POINT 0x2fffff
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#define UCNV_EXT_TO_U_ROUNDTRIP_FLAG ((uint32_t)1<<23)
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#define UCNV_EXT_TO_U_INDEX_MASK 0x3ffff
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#define UCNV_EXT_TO_U_LENGTH_SHIFT 18
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#define UCNV_EXT_TO_U_LENGTH_OFFSET 12
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/* maximum number of indexed UChars */
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#define UCNV_EXT_MAX_UCHARS 19
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#define UCNV_EXT_TO_U_MAKE_WORD(byte, value) (((uint32_t)(byte)<<UCNV_EXT_TO_U_BYTE_SHIFT)|(value))
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#define UCNV_EXT_TO_U_GET_BYTE(word) ((word)>>UCNV_EXT_TO_U_BYTE_SHIFT)
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#define UCNV_EXT_TO_U_GET_VALUE(word) ((word)&UCNV_EXT_TO_U_VALUE_MASK)
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#define UCNV_EXT_TO_U_IS_PARTIAL(value) ((value)<UCNV_EXT_TO_U_MIN_CODE_POINT)
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#define UCNV_EXT_TO_U_GET_PARTIAL_INDEX(value) (value)
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#define UCNV_EXT_TO_U_IS_ROUNDTRIP(value) (((value)&UCNV_EXT_TO_U_ROUNDTRIP_FLAG)!=0)
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#define UCNV_EXT_TO_U_MASK_ROUNDTRIP(value) ((value)&~UCNV_EXT_TO_U_ROUNDTRIP_FLAG)
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/* use after masking off the roundtrip flag */
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#define UCNV_EXT_TO_U_IS_CODE_POINT(value) ((value)<=UCNV_EXT_TO_U_MAX_CODE_POINT)
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#define UCNV_EXT_TO_U_GET_CODE_POINT(value) ((value)-UCNV_EXT_TO_U_MIN_CODE_POINT)
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#define UCNV_EXT_TO_U_GET_INDEX(value) ((value)&UCNV_EXT_TO_U_INDEX_MASK)
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#define UCNV_EXT_TO_U_GET_LENGTH(value) (((value)>>UCNV_EXT_TO_U_LENGTH_SHIFT)-UCNV_EXT_TO_U_LENGTH_OFFSET)
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/* fromUnicode helpers ------------------------------------------------------ */
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/* most trie constants are shared with ucnvmbcs.h */
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/* see similar utrie.h UTRIE_INDEX_SHIFT and UTRIE_DATA_GRANULARITY */
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#define UCNV_EXT_STAGE_2_LEFT_SHIFT 2
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#define UCNV_EXT_STAGE_3_GRANULARITY 4
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/* trie access, returns the stage 3 value=index to stage 3b; s1Index=c>>10 */
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#define UCNV_EXT_FROM_U(stage12, stage3, s1Index, c) \
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(stage3)[ ((int32_t)(stage12)[ (stage12)[s1Index] +(((c)>>4)&0x3f) ]<<UCNV_EXT_STAGE_2_LEFT_SHIFT) +((c)&0xf) ]
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#define UCNV_EXT_FROM_U_LENGTH_SHIFT 24
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#define UCNV_EXT_FROM_U_ROUNDTRIP_FLAG ((uint32_t)1<<31)
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#define UCNV_EXT_FROM_U_RESERVED_MASK 0x60000000
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#define UCNV_EXT_FROM_U_DATA_MASK 0xffffff
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/* special value for "no mapping" to <subchar1> (impossible roundtrip to 0 bytes, value 01) */
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#define UCNV_EXT_FROM_U_SUBCHAR1 0x80000001
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/* at most 3 bytes in the lower part of the value */
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#define UCNV_EXT_FROM_U_MAX_DIRECT_LENGTH 3
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/* maximum number of indexed bytes */
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#define UCNV_EXT_MAX_BYTES 0x1f
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#define UCNV_EXT_FROM_U_IS_PARTIAL(value) (((value)>>UCNV_EXT_FROM_U_LENGTH_SHIFT)==0)
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#define UCNV_EXT_FROM_U_GET_PARTIAL_INDEX(value) (value)
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#define UCNV_EXT_FROM_U_IS_ROUNDTRIP(value) (((value)&UCNV_EXT_FROM_U_ROUNDTRIP_FLAG)!=0)
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#define UCNV_EXT_FROM_U_MASK_ROUNDTRIP(value) ((value)&~UCNV_EXT_FROM_U_ROUNDTRIP_FLAG)
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/* use after masking off the roundtrip flag */
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#define UCNV_EXT_FROM_U_GET_LENGTH(value) (int32_t)(((value)>>UCNV_EXT_FROM_U_LENGTH_SHIFT)&UCNV_EXT_MAX_BYTES)
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/* get bytes or bytes index */
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#define UCNV_EXT_FROM_U_GET_DATA(value) ((value)&UCNV_EXT_FROM_U_DATA_MASK)
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#endif
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