Timothy Flynn 7447a91d7e LibCompress: Decode non-self-referencing back-references in one shot ...

We currently decode back-references one byte at a time, while writing
that byte back out to the output buffer. This is only necessary when the
back-reference refers to itself, i.e. when the back-reference distance
is less than its length. In other cases, we can read the entire back-
reference block in one shot.

Using the "enwik8" file as a test (100MB uncompressed, commonly used in
benchmarks: https://www.mattmahoney.net/dc/enwik8.zip), decompression
time decreases from:

    5.8s to 4.89s on Serenity (cold)
    2.3s to 1.72s on Serenity (warm)
    1.6s to 1.06s on Linux

2023-03-29 13:22:11 +01:00

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