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2.6.6 Extra Length Field

If the match length is 257 or larger, the encoded match length token (or match length, as specified in section 2.6) value is 257, and an encoded Extra Length field follows the other match encoding components, as specified in section 2.6.7, in the bitstream.

Prefix (in binary)

Number of bits to decode

Base value to add to decoded value

0

8

257

10

10

257 + 256

110

12

257 + 256 + 1024

111

15

257

If the encoded match length token is equal to 257, it indicates the length of the match is >= 257. If this is the case, the Extra Length field is after the other match encoding components in the bitstream. If the prefix of the Extra Length field is 0, the match length is the decoded value of the next 8 bits plus 257. If the prefix is 10, the match length is the decoded value of the next 10 bits plus 257 plus 256. If the prefix is 110, the match length is the decoded value of the next 12 bits plus 257 plus 256 plus 1024. If the prefix is 111, the match length is the decoded value of the next 15 bits plus 257.

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