The Tor Browser: intl/icu/source/common/ucnv_ext.h@fc2d59ddac77 (annotated)

intl/icu/source/common/ucnv_ext.h@fc2d59ddac77 (annotated)

intl/icu/source/common/ucnv_ext.h

Wed, 31 Dec 2014 07:22:50 +0100

author: Michael Schloh von Bennewitz <michael@schloh.com>
date: Wed, 31 Dec 2014 07:22:50 +0100
branch: TOR_BUG_3246
changeset 4: fc2d59ddac77
permissions: -rw-r--r--

Correct previous dual key logic pending first delivery installment.

 /*
 ******************************************************************************
 *
 *   Copyright (C) 2003-2013, International Business Machines
 *   Corporation and others.  All Rights Reserved.
 *
 ******************************************************************************
 *   file name:  ucnv_ext.h
 *   encoding:   US-ASCII
 *   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 {
     UCNV_EXT_INDEXES_LENGTH,            /* 0 */
     UCNV_EXT_TO_U_INDEX,                /* 1 */
     UCNV_EXT_TO_U_LENGTH,
     UCNV_EXT_TO_U_UCHARS_INDEX,
     UCNV_EXT_TO_U_UCHARS_LENGTH,
     UCNV_EXT_FROM_U_UCHARS_INDEX,       /* 5 */
     UCNV_EXT_FROM_U_VALUES_INDEX,
     UCNV_EXT_FROM_U_LENGTH,
     UCNV_EXT_FROM_U_BYTES_INDEX,
     UCNV_EXT_FROM_U_BYTES_LENGTH,
     UCNV_EXT_FROM_U_STAGE_12_INDEX,     /* 10 */
     UCNV_EXT_FROM_U_STAGE_1_LENGTH,
     UCNV_EXT_FROM_U_STAGE_12_LENGTH,
     UCNV_EXT_FROM_U_STAGE_3_INDEX,
     UCNV_EXT_FROM_U_STAGE_3_LENGTH,
     UCNV_EXT_FROM_U_STAGE_3B_INDEX,
     UCNV_EXT_FROM_U_STAGE_3B_LENGTH,
     UCNV_EXT_COUNT_BYTES,               /* 17 */
     UCNV_EXT_COUNT_UCHARS,
     UCNV_EXT_FLAGS,
     UCNV_EXT_RESERVED_INDEX,            /* 20, moves with additional indexes */
     UCNV_EXT_SIZE=31,
     UCNV_EXT_INDEXES_MIN_LENGTH=32
 };
 /* get the pointer to an extension array from indexes[index] */
 #define UCNV_EXT_ARRAY(indexes, index, itemType) \
     ((const itemType *)((const char *)(indexes)+(indexes)[index]))
 #define UCNV_GET_MAX_BYTES_PER_UCHAR(indexes) \
     ((indexes)[UCNV_EXT_COUNT_BYTES]&0xff)
 /* 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 24
 #define UCNV_EXT_TO_U_VALUE_MASK 0xffffff
 #define UCNV_EXT_TO_U_MIN_CODE_POINT 0x1f0000
 #define UCNV_EXT_TO_U_MAX_CODE_POINT 0x2fffff
 #define UCNV_EXT_TO_U_ROUNDTRIP_FLAG ((uint32_t)1<<23)
 #define UCNV_EXT_TO_U_INDEX_MASK 0x3ffff
 #define UCNV_EXT_TO_U_LENGTH_SHIFT 18
 #define UCNV_EXT_TO_U_LENGTH_OFFSET 12
 /* maximum number of indexed UChars */
 #define UCNV_EXT_MAX_UCHARS 19
 #define UCNV_EXT_TO_U_MAKE_WORD(byte, value) (((uint32_t)(byte)<<UCNV_EXT_TO_U_BYTE_SHIFT)|(value))
 #define UCNV_EXT_TO_U_GET_BYTE(word) ((word)>>UCNV_EXT_TO_U_BYTE_SHIFT)
 #define UCNV_EXT_TO_U_GET_VALUE(word) ((word)&UCNV_EXT_TO_U_VALUE_MASK)
 #define UCNV_EXT_TO_U_IS_PARTIAL(value) ((value)<UCNV_EXT_TO_U_MIN_CODE_POINT)
 #define UCNV_EXT_TO_U_GET_PARTIAL_INDEX(value) (value)
 #define UCNV_EXT_TO_U_IS_ROUNDTRIP(value) (((value)&UCNV_EXT_TO_U_ROUNDTRIP_FLAG)!=0)
 #define UCNV_EXT_TO_U_MASK_ROUNDTRIP(value) ((value)&~UCNV_EXT_TO_U_ROUNDTRIP_FLAG)
 /* use after masking off the roundtrip flag */
 #define UCNV_EXT_TO_U_IS_CODE_POINT(value) ((value)<=UCNV_EXT_TO_U_MAX_CODE_POINT)
 #define UCNV_EXT_TO_U_GET_CODE_POINT(value) ((value)-UCNV_EXT_TO_U_MIN_CODE_POINT)
 #define UCNV_EXT_TO_U_GET_INDEX(value) ((value)&UCNV_EXT_TO_U_INDEX_MASK)
 #define UCNV_EXT_TO_U_GET_LENGTH(value) (((value)>>UCNV_EXT_TO_U_LENGTH_SHIFT)-UCNV_EXT_TO_U_LENGTH_OFFSET)
 /* 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 2
 #define UCNV_EXT_STAGE_3_GRANULARITY 4
 /* trie access, returns the stage 3 value=index to stage 3b; s1Index=c>>10 */
 #define UCNV_EXT_FROM_U(stage12, stage3, s1Index, c) \
     (stage3)[ ((int32_t)(stage12)[ (stage12)[s1Index] +(((c)>>4)&0x3f) ]<<UCNV_EXT_STAGE_2_LEFT_SHIFT) +((c)&0xf) ]
 #define UCNV_EXT_FROM_U_LENGTH_SHIFT 24
 #define UCNV_EXT_FROM_U_ROUNDTRIP_FLAG ((uint32_t)1<<31)
 #define UCNV_EXT_FROM_U_GOOD_ONE_WAY_FLAG 0x40000000
 #define UCNV_EXT_FROM_U_STATUS_MASK 0xc0000000
 #define UCNV_EXT_FROM_U_RESERVED_MASK 0x20000000
 #define UCNV_EXT_FROM_U_DATA_MASK 0xffffff
 /* special value for "no mapping" to <subchar1> (impossible roundtrip to 0 bytes, value 01) */
 #define UCNV_EXT_FROM_U_SUBCHAR1 0x80000001
 /* at most 3 bytes in the lower part of the value */
 #define UCNV_EXT_FROM_U_MAX_DIRECT_LENGTH 3
 /* maximum number of indexed bytes */
 #define UCNV_EXT_MAX_BYTES 0x1f
 #define UCNV_EXT_FROM_U_IS_PARTIAL(value) (((value)>>UCNV_EXT_FROM_U_LENGTH_SHIFT)==0)
 #define UCNV_EXT_FROM_U_GET_PARTIAL_INDEX(value) (value)
 #define UCNV_EXT_FROM_U_IS_ROUNDTRIP(value) (((value)&UCNV_EXT_FROM_U_ROUNDTRIP_FLAG)!=0)
 #define UCNV_EXT_FROM_U_MASK_ROUNDTRIP(value) ((value)&~UCNV_EXT_FROM_U_ROUNDTRIP_FLAG)
 /* get length; masks away all other bits */
 #define UCNV_EXT_FROM_U_GET_LENGTH(value) (int32_t)(((value)>>UCNV_EXT_FROM_U_LENGTH_SHIFT)&UCNV_EXT_MAX_BYTES)
 /* get bytes or bytes index */
 #define UCNV_EXT_FROM_U_GET_DATA(value) ((value)&UCNV_EXT_FROM_U_DATA_MASK)
 #endif
 #endif

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intl/icu/source/common/ucnv_ext.h@fc2d59ddac77 (annotated)

intl/icu/source/common/ucnv_ext.h