// © 2016 and later: Unicode, Inc. and others. // License & terms of use: http://www.unicode.org/copyright.html /* ****************************************************************************** * * Copyright (C) 2003-2013, International Business Machines * Corporation and others. All Rights Reserved. * ****************************************************************************** * file name: ucnv_ext.h * encoding: UTF-8 * tab size: 8 (not used) * indentation:4 * * created on: 2003jun13 * created by: Markus W. Scherer * * Conversion extensions */ #ifndef __UCNV_EXT_H__ #define __UCNV_EXT_H__ #include "unicode/utypes.h" #if !UCONFIG_NO_CONVERSION #include "unicode/ucnv.h" #include "ucnv_cnv.h" /* * See icuhtml/design/conversion/conversion_extensions.html * * Conversion extensions serve three purposes: * 1. They support m:n mappings. * 2. They support extension-only conversion files that are used together * with the regular conversion data in base files. * 3. They support mappings with more complicated meta data, * for example "good one-way" mappings (|4). * * A base file may contain an extension table (explicitly requested or * implicitly generated for m:n mappings), but its extension table is not * used when an extension-only file is used. * * It is an error if a base file contains any regular (not extension) mapping * from the same sequence as a mapping in the extension file * because the base mapping would hide the extension mapping. * * * Data for conversion extensions: * * One set of data structures per conversion direction (to/from Unicode). * The data structures are sorted by input units to allow for binary search. * Input sequences of more than one unit are handled like contraction tables * in collation: * The lookup value of a unit points to another table that is to be searched * for the next unit, recursively. * * For conversion from Unicode, the initial code point is looked up in * a 3-stage trie for speed, * with an additional table of unique results to save space. * * Long output strings are stored in separate arrays, with length and index * in the lookup tables. * Output results also include a flag distinguishing roundtrip from * (reverse) fallback mappings. * * Input Unicode strings must not begin or end with unpaired surrogates * to avoid problems with matches on parts of surrogate pairs. * * Mappings from multiple characters (code points or codepage state * table sequences) must be searched preferring the longest match. * For this to work and be efficient, the variable-width table must contain * all mappings that contain prefixes of the multiple characters. * If an extension table is built on top of a base table in another file * and a base table entry is a prefix of a multi-character mapping, then * this is an error. * * * Implementation note: * * Currently, the parser and several checks in the code limit the number * of UChars or bytes in a mapping to * UCNV_EXT_MAX_UCHARS and UCNV_EXT_MAX_BYTES, respectively, * which are output value limits in the data structure. * * For input, this is not strictly necessary - it is a hard limit only for the * buffers in UConverter that are used to store partial matches. * * Input sequences could otherwise be arbitrarily long if partial matches * need not be stored (i.e., if a sequence does not span several buffers with too * many units before the last buffer), although then results would differ * depending on whether partial matches exceed the limits or not, * which depends on the pattern of buffer sizes. * * * Data structure: * * int32_t indexes[>=32]; * * Array of indexes and lengths etc. The length of the array is at least 32. * The actual length is stored in indexes[0] to be forward compatible. * * Each index to another array is the number of bytes from indexes[]. * Each length of an array is the number of array base units in that array. * * Some of the structures may not be present, in which case their indexes * and lengths are 0. * * Usage of indexes[i]: * [0] length of indexes[] * * // to Unicode table * [1] index of toUTable[] (array of uint32_t) * [2] length of toUTable[] * [3] index of toUUChars[] (array of UChar) * [4] length of toUUChars[] * * // from Unicode table, not for the initial code point * [5] index of fromUTableUChars[] (array of UChar) * [6] index of fromUTableValues[] (array of uint32_t) * [7] length of fromUTableUChars[] and fromUTableValues[] * [8] index of fromUBytes[] (array of char) * [9] length of fromUBytes[] * * // from Unicode trie for initial-code point lookup * [10] index of fromUStage12[] (combined array of uint16_t for stages 1 & 2) * [11] length of stage 1 portion of fromUStage12[] * [12] length of fromUStage12[] * [13] index of fromUStage3[] (array of uint16_t indexes into fromUStage3b[]) * [14] length of fromUStage3[] * [15] index of fromUStage3b[] (array of uint32_t like fromUTableValues[]) * [16] length of fromUStage3b[] * * [17] Bit field containing numbers of bytes: * 31..24 reserved, 0 * 23..16 maximum input bytes * 15.. 8 maximum output bytes * 7.. 0 maximum bytes per UChar * * [18] Bit field containing numbers of UChars: * 31..24 reserved, 0 * 23..16 maximum input UChars * 15.. 8 maximum output UChars * 7.. 0 maximum UChars per byte * * [19] Bit field containing flags: * (extension table unicodeMask) * 1 UCNV_HAS_SURROGATES flag for the extension table * 0 UCNV_HAS_SUPPLEMENTARY flag for the extension table * * [20]..[30] reserved, 0 * [31] number of bytes for the entire extension structure * [>31] reserved; there are indexes[0] indexes * * * uint32_t toUTable[]; * * Array of byte/value pairs for lookups for toUnicode conversion. * The array is partitioned into sections like collation contraction tables. * Each section contains one word with the number of following words and * a default value for when the lookup in this section yields no match. * * A section is sorted in ascending order of input bytes, * allowing for fast linear or binary searches. * The builder may store entries for a contiguous range of byte values * (compare difference between the first and last one with count), * which then allows for direct array access. * The builder should always do this for the initial table section. * * Entries may have 0 values, see below. * No two entries in a section have the same byte values. * * Each uint32_t contains an input byte value in bits 31..24 and the * corresponding lookup value in bits 23..0. * Interpret the value as follows: * if(value==0) { * no match, see below * } else if(value<0x1f0000) { * partial match - use value as index to the next toUTable section * and match the next unit; (value indexes toUTable[value]) * } else { * if(bit 23 set) { * roundtrip; * } else { * fallback; * } * unset value bit 23; * if(value<=0x2fffff) { * (value-0x1f0000) is a code point; (BMP: value<=0x1fffff) * } else { * bits 17..0 (value&0x3ffff) is an index to * the result UChars in toUUChars[]; (0 indexes toUUChars[0]) * length of the result=((value>>18)-12); (length=0..19) * } * } * * The first word in a section contains the number of following words in the * input byte position (bits 31..24, number=1..0xff). * The value of the initial word is used when the current byte is not found * in this section. * If the value is not 0, then it represents a result as above. * If the value is 0, then the search has to return a shorter match with an * earlier default value as the result, or result in "unmappable" even for the * initial bytes. * If the value is 0 for the initial toUTable entry, then the initial byte * does not start any mapping input. * * * UChar toUUChars[]; * * Contains toUnicode mapping results, stored as sequences of UChars. * Indexes and lengths stored in the toUTable[]. * * * UChar fromUTableUChars[]; * uint32_t fromUTableValues[]; * * The fromUTable is split into two arrays, but works otherwise much like * the toUTable. The array is partitioned into sections like collation * contraction tables and toUTable. * A row in the table consists of same-index entries in fromUTableUChars[] * and fromUTableValues[]. * * Interpret a value as follows: * if(value==0) { * no match, see below * } else if(value<=0xffffff) { (bits 31..24 are 0) * partial match - use value as index to the next fromUTable section * and match the next unit; (value indexes fromUTable[value]) * } else { * if(value==0x80000001) { * return no mapping, but request for <subchar1>; * } * if(bit 31 set) { * roundtrip (|0); * } else if(bit 30 set) { * "good one-way" mapping (|4); -- new in ICU4C 51, _MBCSHeader.version 5.4/4.4 * } else { * normal fallback (|1); * } * // bit 29 reserved, 0 * length=(value>>24)&0x1f; (bits 28..24) * if(length==1..3) { * bits 23..0 contain 1..3 bytes, padded with 00s on the left; * } else { * bits 23..0 (value&0xffffff) is an index to * the result bytes in fromUBytes[]; (0 indexes fromUBytes[0]) * } * } * * The first pair in a section contains the number of following pairs in the * UChar position (16 bits, number=1..0xffff). * The value of the initial pair is used when the current UChar is not found * in this section. * If the value is not 0, then it represents a result as above. * If the value is 0, then the search has to return a shorter match with an * earlier default value as the result, or result in "unmappable" even for the * initial UChars. * * If the from Unicode trie is present, then the from Unicode search tables * are not used for initial code points. * In this case, the first entries (index 0) in the tables are not used * (reserved, set to 0) because a value of 0 is used in trie results * to indicate no mapping. * * * uint16_t fromUStage12[]; * * Stages 1 & 2 of a trie that maps an initial code point. * Indexes in stage 1 are all offset by the length of stage 1 so that the * same array pointer can be used for both stages. * If (c>>10)>=(length of stage 1) then c does not start any mapping. * Same bit distribution as for regular conversion tries. * * * uint16_t fromUStage3[]; * uint32_t fromUStage3b[]; * * Stage 3 of the trie. The first array simply contains indexes to the second, * which contains words in the same format as fromUTableValues[]. * Use a stage 3 granularity of 4, which allows for 256k stage 3 entries, * and 16-bit entries in stage 3 allow for 64k stage 3b entries. * The stage 3 granularity means that the stage 2 entry needs to be left-shifted. * * Two arrays are used because it is expected that more than half of the stage 3 * entries will be zero. The 16-bit index stage 3 array saves space even * considering storing a total of 6 bytes per non-zero entry in both arrays * together. * Using a stage 3 granularity of >1 diminishes the compactability in that stage * but provides a larger effective addressing space in stage 2. * All but the final result stage use 16-bit entries to save space. * * fromUStage3b[] contains a zero for "no mapping" at its index 0, * and may contain UCNV_EXT_FROM_U_SUBCHAR1 at index 1 for "<subchar1> SUB mapping" * (i.e., "no mapping" with preference for <subchar1> rather than <subchar>), * and all other items are unique non-zero results. * * The default value of a fromUTableValues[] section that is referenced * _directly_ from a fromUStage3b[] item may also be UCNV_EXT_FROM_U_SUBCHAR1, * but this value must not occur anywhere else in fromUTableValues[] * because "no mapping" is always a property of a single code point, * never of multiple. * * * char fromUBytes[]; * * Contains fromUnicode mapping results, stored as sequences of chars. * Indexes and lengths stored in the fromUTableValues[]. */ enum { … }; /* get the pointer to an extension array from indexes[index] */ #define UCNV_EXT_ARRAY(indexes, index, itemType) … #define UCNV_GET_MAX_BYTES_PER_UCHAR(indexes) … /* internal API ------------------------------------------------------------- */ U_CFUNC UBool ucnv_extInitialMatchToU(UConverter *cnv, const int32_t *cx, int32_t firstLength, const char **src, const char *srcLimit, UChar **target, const UChar *targetLimit, int32_t **offsets, int32_t srcIndex, UBool flush, UErrorCode *pErrorCode); U_CFUNC UChar32 ucnv_extSimpleMatchToU(const int32_t *cx, const char *source, int32_t length, UBool useFallback); U_CFUNC void ucnv_extContinueMatchToU(UConverter *cnv, UConverterToUnicodeArgs *pArgs, int32_t srcIndex, UErrorCode *pErrorCode); U_CFUNC UBool ucnv_extInitialMatchFromU(UConverter *cnv, const int32_t *cx, UChar32 cp, const UChar **src, const UChar *srcLimit, char **target, const char *targetLimit, int32_t **offsets, int32_t srcIndex, UBool flush, UErrorCode *pErrorCode); U_CFUNC int32_t ucnv_extSimpleMatchFromU(const int32_t *cx, UChar32 cp, uint32_t *pValue, UBool useFallback); U_CFUNC void ucnv_extContinueMatchFromU(UConverter *cnv, UConverterFromUnicodeArgs *pArgs, int32_t srcIndex, UErrorCode *pErrorCode); /* * Add code points and strings to the set according to the extension mappings. * Limitation on the UConverterSetFilter: * The filters currently assume that they are used with 1:1 mappings. * They only apply to single input code points, and then they pass through * only mappings with single-charset-code results. * For example, the Shift-JIS filter only works for 2-byte results and tests * that those 2 bytes are in the JIS X 0208 range of Shift-JIS. */ U_CFUNC void ucnv_extGetUnicodeSet(const UConverterSharedData *sharedData, const USetAdder *sa, UConverterUnicodeSet which, UConverterSetFilter filter, UErrorCode *pErrorCode); /* toUnicode helpers -------------------------------------------------------- */ #define UCNV_EXT_TO_U_BYTE_SHIFT … #define UCNV_EXT_TO_U_VALUE_MASK … #define UCNV_EXT_TO_U_MIN_CODE_POINT … #define UCNV_EXT_TO_U_MAX_CODE_POINT … #define UCNV_EXT_TO_U_ROUNDTRIP_FLAG … #define UCNV_EXT_TO_U_INDEX_MASK … #define UCNV_EXT_TO_U_LENGTH_SHIFT … #define UCNV_EXT_TO_U_LENGTH_OFFSET … /* maximum number of indexed UChars */ #define UCNV_EXT_MAX_UCHARS … #define UCNV_EXT_TO_U_MAKE_WORD(byte, value) … #define UCNV_EXT_TO_U_GET_BYTE(word) … #define UCNV_EXT_TO_U_GET_VALUE(word) … #define UCNV_EXT_TO_U_IS_PARTIAL(value) … #define UCNV_EXT_TO_U_GET_PARTIAL_INDEX(value) … #define UCNV_EXT_TO_U_IS_ROUNDTRIP(value) … #define UCNV_EXT_TO_U_MASK_ROUNDTRIP(value) … /* use after masking off the roundtrip flag */ #define UCNV_EXT_TO_U_IS_CODE_POINT(value) … #define UCNV_EXT_TO_U_GET_CODE_POINT(value) … #define UCNV_EXT_TO_U_GET_INDEX(value) … #define UCNV_EXT_TO_U_GET_LENGTH(value) … /* fromUnicode helpers ------------------------------------------------------ */ /* most trie constants are shared with ucnvmbcs.h */ /* see similar utrie.h UTRIE_INDEX_SHIFT and UTRIE_DATA_GRANULARITY */ #define UCNV_EXT_STAGE_2_LEFT_SHIFT … #define UCNV_EXT_STAGE_3_GRANULARITY … /* trie access, returns the stage 3 value=index to stage 3b; s1Index=c>>10 */ #define UCNV_EXT_FROM_U(stage12, stage3, s1Index, c) … #define UCNV_EXT_FROM_U_LENGTH_SHIFT … #define UCNV_EXT_FROM_U_ROUNDTRIP_FLAG … #define UCNV_EXT_FROM_U_GOOD_ONE_WAY_FLAG … #define UCNV_EXT_FROM_U_STATUS_MASK … #define UCNV_EXT_FROM_U_RESERVED_MASK … #define UCNV_EXT_FROM_U_DATA_MASK … /* special value for "no mapping" to <subchar1> (impossible roundtrip to 0 bytes, value 01) */ #define UCNV_EXT_FROM_U_SUBCHAR1 … /* at most 3 bytes in the lower part of the value */ #define UCNV_EXT_FROM_U_MAX_DIRECT_LENGTH … /* maximum number of indexed bytes */ #define UCNV_EXT_MAX_BYTES … #define UCNV_EXT_FROM_U_IS_PARTIAL(value) … #define UCNV_EXT_FROM_U_GET_PARTIAL_INDEX(value) … #define UCNV_EXT_FROM_U_IS_ROUNDTRIP(value) … #define UCNV_EXT_FROM_U_MASK_ROUNDTRIP(value) … /* get length; masks away all other bits */ #define UCNV_EXT_FROM_U_GET_LENGTH(value) … /* get bytes or bytes index */ #define UCNV_EXT_FROM_U_GET_DATA(value) … #endif #endif
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