MCL/sf/os/textandloc: comparison fontservices/textshaperplugin/IcuSource/common/ucnv

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+/*
+******************************************************************************
+*
+*   Copyright (C) 2003-2004, 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 two 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.
+*
+* 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;
+*       } else {
+*         fallback;
+*       }
+*       // bits 30..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);
+U_CFUNC void
+ucnv_extGetUnicodeSet(const UConverterSharedData *sharedData,
+const USetAdder *sa,
+UConverterUnicodeSet which,
+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_RESERVED_MASK 0x60000000
+#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)
+/* use after masking off the roundtrip flag */
+#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