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Diffstat (limited to 'deps/icu-small/source/common/ucptrie_impl.h')
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diff --git a/deps/icu-small/source/common/ucptrie_impl.h b/deps/icu-small/source/common/ucptrie_impl.h new file mode 100644 index 00000000000..1fe6a18ac53 --- /dev/null +++ b/deps/icu-small/source/common/ucptrie_impl.h @@ -0,0 +1,289 @@ +// © 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 0x54726933 +#define UCPTRIE_OE_SIG 0x33697254 + +/** + * Header data for the binary, memory-mappable representation of a UCPTrie/CodePointTrie. + * @internal + */ +struct UCPTrieHeader { + /** "Tri3" in big-endian US-ASCII (0x54726933) */ + uint32_t signature; + + /** + * Options bit field: + * Bits 15..12: Data length bits 19..16. + * Bits 11..8: Data null block offset bits 19..16. + * Bits 7..6: UCPTrieType + * Bits 5..3: Reserved (0). + * Bits 2..0: UCPTrieValueWidth + */ + uint16_t options; + + /** Total length of the index tables. */ + uint16_t indexLength; + + /** Data length bits 15..0. */ + uint16_t dataLength; + + /** Index-3 null block offset, 0x7fff or 0xffff if none. */ + uint16_t index3NullOffset; + + /** Data null block offset bits 15..0, 0xfffff if none. */ + uint16_t dataNullOffset; + + /** + * First code point of the single-value range ending with U+10ffff, + * rounded up and then shifted right by UCPTRIE_SHIFT_2. + */ + uint16_t shiftedHighStart; +}; + +/** + * Constants for use with UCPTrieHeader.options. + * @internal + */ +enum { + UCPTRIE_OPTIONS_DATA_LENGTH_MASK = 0xf000, + UCPTRIE_OPTIONS_DATA_NULL_OFFSET_MASK = 0xf00, + UCPTRIE_OPTIONS_RESERVED_MASK = 0x38, + UCPTRIE_OPTIONS_VALUE_BITS_MASK = 7, + /** + * 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. + */ + UCPTRIE_NO_INDEX3_NULL_OFFSET = 0x7fff, + UCPTRIE_NO_DATA_NULL_OFFSET = 0xfffff +}; + +// Internal constants. +enum { + /** The length of the BMP index table. 1024=0x400 */ + UCPTRIE_BMP_INDEX_LENGTH = 0x10000 >> UCPTRIE_FAST_SHIFT, + + UCPTRIE_SMALL_LIMIT = 0x1000, + UCPTRIE_SMALL_INDEX_LENGTH = UCPTRIE_SMALL_LIMIT >> UCPTRIE_FAST_SHIFT, + + /** Shift size for getting the index-3 table offset. */ + UCPTRIE_SHIFT_3 = 4, + + /** Shift size for getting the index-2 table offset. */ + UCPTRIE_SHIFT_2 = 5 + UCPTRIE_SHIFT_3, + + /** Shift size for getting the index-1 table offset. */ + UCPTRIE_SHIFT_1 = 5 + UCPTRIE_SHIFT_2, + + /** + * Difference between two shift sizes, + * for getting an index-2 offset from an index-3 offset. 5=9-4 + */ + UCPTRIE_SHIFT_2_3 = UCPTRIE_SHIFT_2 - UCPTRIE_SHIFT_3, + + /** + * Difference between two shift sizes, + * for getting an index-1 offset from an index-2 offset. 5=14-9 + */ + UCPTRIE_SHIFT_1_2 = UCPTRIE_SHIFT_1 - UCPTRIE_SHIFT_2, + + /** + * Number of index-1 entries for the BMP. (4) + * This part of the index-1 table is omitted from the serialized form. + */ + UCPTRIE_OMITTED_BMP_INDEX_1_LENGTH = 0x10000 >> UCPTRIE_SHIFT_1, + + /** Number of entries in an index-2 block. 32=0x20 */ + UCPTRIE_INDEX_2_BLOCK_LENGTH = 1 << UCPTRIE_SHIFT_1_2, + + /** Mask for getting the lower bits for the in-index-2-block offset. */ + UCPTRIE_INDEX_2_MASK = UCPTRIE_INDEX_2_BLOCK_LENGTH - 1, + + /** Number of code points per index-2 table entry. 512=0x200 */ + UCPTRIE_CP_PER_INDEX_2_ENTRY = 1 << UCPTRIE_SHIFT_2, + + /** Number of entries in an index-3 block. 32=0x20 */ + UCPTRIE_INDEX_3_BLOCK_LENGTH = 1 << UCPTRIE_SHIFT_2_3, + + /** Mask for getting the lower bits for the in-index-3-block offset. */ + UCPTRIE_INDEX_3_MASK = UCPTRIE_INDEX_3_BLOCK_LENGTH - 1, + + /** Number of entries in a small data block. 16=0x10 */ + UCPTRIE_SMALL_DATA_BLOCK_LENGTH = 1 << UCPTRIE_SHIFT_3, + + /** Mask for getting the lower bits for the in-small-data-block offset. */ + UCPTRIE_SMALL_DATA_MASK = UCPTRIE_SMALL_DATA_BLOCK_LENGTH - 1 +}; + +typedef UChar32 +UCPTrieGetRange(const void *trie, UChar32 start, + UCPMapValueFilter *filter, const void *context, uint32_t *pValue); + +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 http://site.icu-project.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 |