60 lines
2.3 KiB
Go
60 lines
2.3 KiB
Go
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// This file was generated by go generate; DO NOT EDIT
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package runenames
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// This file contains code common to gen.go and the package code.
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// The mapping from rune to string (i.e. offset and length in the data string)
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// is encoded as a two level table. The first level maps from contiguous rune
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// ranges [runeOffset, runeOffset+runeLength) to entries. Entries are either
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// direct (for repeated names such as "<CJK Ideograph>") or indirect (for runs
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// of unique names such as "SPACE", "EXCLAMATION MARK", "QUOTATION MARK", ...).
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//
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// Each first level table element is 64 bits. The runeOffset (21 bits) and
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// runeLength (16 bits) take the 37 high bits. The entry takes the 27 low bits,
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// with directness encoded in the least significant bit.
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//
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// A direct entry encodes a dataOffset (18 bits) and dataLength (8 bits) in the
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// data string. 18 bits is too short to encode the entire data string's length,
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// but the data string's contents are arranged so that all of the few direct
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// entries' offsets come before all of the many indirect entries' offsets.
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//
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// An indirect entry encodes a dataBase (10 bits) and a table1Offset (16 bits).
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// The table1Offset is the start of a range in the second level table. The
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// length of that range is the same as the runeLength.
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//
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// Each second level table element is 16 bits, an index into data, relative to
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// a bias equal to (dataBase << dataBaseUnit). That (bias + index) is the
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// (dataOffset + dataLength) in the data string. The dataOffset is implied by
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// the previous table element (with the same implicit bias).
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const (
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bitsRuneOffset = 21
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bitsRuneLength = 16
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bitsDataOffset = 18
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bitsDataLength = 8
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bitsDirect = 1
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bitsDataBase = 10
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bitsTable1Offset = 16
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shiftRuneOffset = 0 + bitsDirect + bitsDataLength + bitsDataOffset + bitsRuneLength
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shiftRuneLength = 0 + bitsDirect + bitsDataLength + bitsDataOffset
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shiftDataOffset = 0 + bitsDirect + bitsDataLength
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shiftDataLength = 0 + bitsDirect
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shiftDirect = 0
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shiftDataBase = 0 + bitsDirect + bitsTable1Offset
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shiftTable1Offset = 0 + bitsDirect
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maskRuneLength = 1<<bitsRuneLength - 1
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maskDataOffset = 1<<bitsDataOffset - 1
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maskDataLength = 1<<bitsDataLength - 1
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maskDirect = 1<<bitsDirect - 1
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maskDataBase = 1<<bitsDataBase - 1
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maskTable1Offset = 1<<bitsTable1Offset - 1
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dataBaseUnit = 10
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)
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