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steve-chamberlin 2016-05-06 13:16:45 -07:00
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@ -5,10 +5,10 @@ The algorithm is based on the classic LZ77 compression scheme, with a sliding hi
The compressed data is a series of tokens in this format:
LIT = 00aaaaaa next aaaaaa+1 bytes are literals
BR0 = 01baaaaa backref to offset aaaaa, length b+3
EOF = 01x00000 end of file
BR1 = 10bbbaaa'aaaaaaaa backref to offset aaa'aaaaaaaa, length bbb+3
BR2 = 11bbbbba'aaaaaaaa'aaaaaaaa backref to offset a'aaaaaaaa'aaaaaaaa, length lookup_table[bbbbb]
* _LIT = 00aaaaaa = next aaaaaa+1 bytes are literals
* BR0 = 01baaaaa = backref to offset aaaaa, length b+3
* EOF = 01x00000 = end of file
* BR1 = 10bbbaaa'aaaaaaaa = backref to offset aaa'aaaaaaaa, length bbb+3
* BR2 = 11bbbbba'aaaaaaaa'aaaaaaaa = backref to offset a'aaaaaaaa'aaaaaaaa, length lookup_table[bbbbb]
The length lookup table enables encoding of backrefs up to 256 bytes in length using only 5 bits, though some longer lengths can't be encoded directly. These are encoded as two successive backrefs, each with a smaller length.