// © 2017 and later: Unicode, Inc. and others. // License & terms of use: http://www.unicode.org/copyright.html // ucptrie_impl.h (modified from utrie2_impl.h) // created: 2017dec29 Markus W. Scherer #ifndef __UCPTRIE_IMPL_H__ #define __UCPTRIE_IMPL_H__ #include "unicode/ucptrie.h" #ifdef UCPTRIE_DEBUG #include "unicode/umutablecptrie.h" #endif // UCPTrie signature values, in platform endianness and opposite endianness. // The UCPTrie signature ASCII byte values spell "Tri3". #define UCPTRIE_SIG … #define UCPTRIE_OE_SIG … /** * Header data for the binary, memory-mappable representation of a UCPTrie/CodePointTrie. * @internal */ struct UCPTrieHeader { … }; // Constants for use with UCPTrieHeader.options. constexpr uint16_t UCPTRIE_OPTIONS_DATA_LENGTH_MASK = …; constexpr uint16_t UCPTRIE_OPTIONS_DATA_NULL_OFFSET_MASK = …; constexpr uint16_t UCPTRIE_OPTIONS_RESERVED_MASK = …; constexpr uint16_t UCPTRIE_OPTIONS_VALUE_BITS_MASK = …; /** * Value for index3NullOffset which indicates that there is no index-3 null block. * Bit 15 is unused for this value because this bit is used if the index-3 contains * 18-bit indexes. */ constexpr int32_t UCPTRIE_NO_INDEX3_NULL_OFFSET = …; constexpr int32_t UCPTRIE_NO_DATA_NULL_OFFSET = …; // Internal constants. /** The length of the BMP index table. 1024=0x400 */ constexpr int32_t UCPTRIE_BMP_INDEX_LENGTH = …; constexpr int32_t UCPTRIE_SMALL_LIMIT = …; constexpr int32_t UCPTRIE_SMALL_INDEX_LENGTH = …; /** Shift size for getting the index-3 table offset. */ constexpr int32_t UCPTRIE_SHIFT_3 = …; /** Shift size for getting the index-2 table offset. */ constexpr int32_t UCPTRIE_SHIFT_2 = …; /** Shift size for getting the index-1 table offset. */ constexpr int32_t UCPTRIE_SHIFT_1 = …; /** * Difference between two shift sizes, * for getting an index-2 offset from an index-3 offset. 5=9-4 */ constexpr int32_t UCPTRIE_SHIFT_2_3 = …; /** * Difference between two shift sizes, * for getting an index-1 offset from an index-2 offset. 5=14-9 */ constexpr int32_t UCPTRIE_SHIFT_1_2 = …; /** * Number of index-1 entries for the BMP. (4) * This part of the index-1 table is omitted from the serialized form. */ constexpr int32_t UCPTRIE_OMITTED_BMP_INDEX_1_LENGTH = …; /** Number of entries in an index-2 block. 32=0x20 */ constexpr int32_t UCPTRIE_INDEX_2_BLOCK_LENGTH = …; /** Mask for getting the lower bits for the in-index-2-block offset. */ constexpr int32_t UCPTRIE_INDEX_2_MASK = …; /** Number of code points per index-2 table entry. 512=0x200 */ constexpr int32_t UCPTRIE_CP_PER_INDEX_2_ENTRY = …; /** Number of entries in an index-3 block. 32=0x20 */ constexpr int32_t UCPTRIE_INDEX_3_BLOCK_LENGTH = …; /** Mask for getting the lower bits for the in-index-3-block offset. */ constexpr int32_t UCPTRIE_INDEX_3_MASK = …; /** Number of entries in a small data block. 16=0x10 */ constexpr int32_t UCPTRIE_SMALL_DATA_BLOCK_LENGTH = …; /** Mask for getting the lower bits for the in-small-data-block offset. */ constexpr int32_t UCPTRIE_SMALL_DATA_MASK = …; UCPTrieGetRange; U_CFUNC UChar32 ucptrie_internalGetRange(UCPTrieGetRange *getRange, const void *trie, UChar32 start, UCPMapRangeOption option, uint32_t surrogateValue, UCPMapValueFilter *filter, const void *context, uint32_t *pValue); #ifdef UCPTRIE_DEBUG U_CFUNC void ucptrie_printLengths(const UCPTrie *trie, const char *which); U_CFUNC void umutablecptrie_setName(UMutableCPTrie *builder, const char *name); #endif /* * Format of the binary, memory-mappable representation of a UCPTrie/CodePointTrie. * For overview information see https://icu.unicode.org/design/struct/utrie * * The binary trie data should be 32-bit-aligned. * The overall layout is: * * UCPTrieHeader header; -- 16 bytes, see struct definition above * uint16_t index[header.indexLength]; * uintXY_t data[header.dataLength]; * * The trie data array is an array of uint16_t, uint32_t, or uint8_t, * specified via the UCPTrieValueWidth when building the trie. * The data array is 32-bit-aligned for uint32_t, otherwise 16-bit-aligned. * The overall length of the trie data is a multiple of 4 bytes. * (Padding is added at the end of the index array and/or near the end of the data array as needed.) * * The length of the data array (dataLength) is stored as an integer split across two fields * of the header struct (high bits in header.options). * * The trie type can be "fast" or "small" which determines the index structure, * specified via the UCPTrieType when building the trie. * * The type and valueWidth are stored in the header.options. * There are reserved type and valueWidth values, and reserved header.options bits. * They could be used in future format extensions. * Code reading the trie structure must fail with an error when unknown values or options are set. * * Values for ASCII character (U+0000..U+007F) can always be found at the start of the data array. * * Values for code points below a type-specific fast-indexing limit are found via two-stage lookup. * For a "fast" trie, the limit is the BMP/supplementary boundary at U+10000. * For a "small" trie, the limit is UCPTRIE_SMALL_MAX+1=U+1000. * * All code points in the range highStart..U+10FFFF map to a single highValue * which is stored at the second-to-last position of the data array. * (See UCPTRIE_HIGH_VALUE_NEG_DATA_OFFSET.) * The highStart value is header.shiftedHighStart<<UCPTRIE_SHIFT_2. * (UCPTRIE_SHIFT_2=9) * * Values for code points fast_limit..highStart-1 are found via four-stage lookup. * The data block size is smaller for this range than for the fast range. * This together with more index stages with small blocks makes this range * more easily compactable. * * There is also a trie error value stored at the last position of the data array. * (See UCPTRIE_ERROR_VALUE_NEG_DATA_OFFSET.) * It is intended to be returned for inputs that are not Unicode code points * (outside U+0000..U+10FFFF), or in string processing for ill-formed input * (unpaired surrogate in UTF-16, ill-formed UTF-8 subsequence). * * For a "fast" trie: * * The index array starts with the BMP index table for BMP code point lookup. * Its length is 1024=0x400. * * The supplementary index-1 table follows the BMP index table. * Variable length, for code points up to highStart-1. * Maximum length 64=0x40=0x100000>>UCPTRIE_SHIFT_1. * (For 0x100000 supplementary code points U+10000..U+10ffff.) * * After this index-1 table follow the variable-length index-3 and index-2 tables. * * The supplementary index tables are omitted completely * if there is only BMP data (highStart<=U+10000). * * For a "small" trie: * * The index array starts with a fast-index table for lookup of code points U+0000..U+0FFF. * * The "supplementary" index tables are always stored. * The index-1 table starts from U+0000, its maximum length is 68=0x44=0x110000>>UCPTRIE_SHIFT_1. * * For both trie types: * * The last index-2 block may be a partial block, storing indexes only for code points * below highStart. * * Lookup for ASCII code point c: * * Linear access from the start of the data array. * * value = data[c]; * * Lookup for fast-range code point c: * * Shift the code point right by UCPTRIE_FAST_SHIFT=6 bits, * fetch the index array value at that offset, * add the lower code point bits, index into the data array. * * value = data[index[c>>6] + (c&0x3f)]; * * (This works for ASCII as well.) * * Lookup for small-range code point c below highStart: * * Split the code point into four bit fields using several sets of shifts & masks * to read consecutive values from the index-1, index-2, index-3 and data tables. * * If all of the data block offsets in an index-3 block fit within 16 bits (up to 0xffff), * then the data block offsets are stored directly as uint16_t. * * Otherwise (this is very unusual but possible), the index-2 entry for the index-3 block * has bit 15 (0x8000) set, and each set of 8 index-3 entries is preceded by * an additional uint16_t word. Data block offsets are 18 bits wide, with the top 2 bits stored * in the additional word. * * See ucptrie_internalSmallIndex() for details. * * (In a "small" trie, this works for ASCII and below-fast_limit code points as well.) * * Compaction: * * Multiple code point ranges ("blocks") that are aligned on certain boundaries * (determined by the shifting/bit fields of code points) and * map to the same data values normally share a single subsequence of the data array. * Data blocks can also overlap partially. * (Depending on the builder code finding duplicate and overlapping blocks.) * * Iteration over same-value ranges: * * Range iteration (ucptrie_getRange()) walks the structure from a start code point * until some code point is found that maps to a different value; * the end of the returned range is just before that. * * The header.dataNullOffset (split across two header fields, high bits in header.options) * is the offset of a widely shared data block filled with one single value. * It helps quickly skip over large ranges of data with that value. * The builder must ensure that if the start of any data block (fast or small) * matches the dataNullOffset, then the whole block must be filled with the null value. * Special care must be taken if there is no fast null data block * but a small one, which is shorter, and it matches the *start* of some fast data block. * * Similarly, the header.index3NullOffset is the index-array offset of an index-3 block * where all index entries point to the dataNullOffset. * If there is no such data or index-3 block, then these offsets are set to * values that cannot be reached (data offset out of range/reserved index offset), * normally UCPTRIE_NO_DATA_NULL_OFFSET or UCPTRIE_NO_INDEX3_NULL_OFFSET respectively. */ #endif
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