flate: Improve level 1-3 compression #678
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Use 5 byte hash instead of 4 byte hash. This improves compression in most cases and will also yield faster decompression. Little to no performance impact. Before/after: ``` file out level insize outsize millis nyc-taxi-data-10M.csv gzkp 1 3325605752 922273214 14065 225.49 nyc-taxi-data-10M.csv gzkp 1 3325605752 846471964 14564 217.76 nyc-taxi-data-10M.csv gzkp 2 3325605752 883782053 15683 202.22 nyc-taxi-data-10M.csv gzkp 2 3325605752 815766227 15057 210.63 nyc-taxi-data-10M.csv gzkp 3 3325605752 878726683 17308 183.24 nyc-taxi-data-10M.csv gzkp 3 3325605752 807241782 17184 184.56 nyc-taxi-data-10M.csv gzkp 4 3325605752 789447233 20651 153.57 nyc-taxi-data-10M.csv gzkp 4 3325605752 789447233 20862 152.02 file out level insize outsize millis mb/s enwik9 gzkp 1 1000000000 382781160 5713 166.90 enwik9 gzkp 1 1000000000 374131553 5926 160.90 enwik9 gzkp 2 1000000000 371351753 6131 155.55 enwik9 gzkp 2 1000000000 361881529 6007 158.74 enwik9 gzkp 3 1000000000 364881746 6891 138.39 enwik9 gzkp 3 1000000000 355065173 7043 135.39 enwik9 gzkp 4 1000000000 342732211 8339 114.36 enwik9 gzkp 4 1000000000 342732211 8327 114.52 ```
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Use 5 byte hash instead of 4 byte hash.
This improves compression in most cases and will also yield faster decompression. Little to no performance impact.
Before/after: