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—base:dictionary_compression [2022-08-14 12:10] (current) – created martin_piper
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 +Full source and example code is in here: https://github.com/martinpiper/C64Public/tree/master/DictionaryCompression
 +
 +
 +A variant of literal/copy compression (LZMPiE) that uses an extra common dictionary  (hence LZMPiED) calculated from multiple input files, to reduce overall compressed data size.
 +
 +The build for this tool is also a good demonstration on how to unit test 6502 code along with java code.
 +
 +Command line parameters:
 +
 +    <dictionary size in bytes (decimal)> <output file name> <start offset in files (skip start bytes) (decimal)> [input files]
 +    
 +
 +
 +Example usage:
 +
 +    java -jar target\DictionaryCompression-1.0-SNAPSHOT-jar-with-dependencies.jar 1024 target/compressed 2 TestData/Mule.prg TestData/MeanStreak.prg TestData/Lobster.prg TestData/Dinosaur_Disco.prg "TestData/Turrican remixed.prg" TestData/Nintendo.prg TestData/WizballGuitar.prg
 +
 +Which equals 11,745 bytes
 +
 +Compare this with the result of using LZMPi to compress each file individually:
 +
 +    ..\bin\LZMPi.exe -c TestData/Mule.prg target/compressed_Mule.prg.cmp2
 +    ..\bin\LZMPi.exe -c TestData/MeanStreak.prg target/compressed_MeanStreak.prg.cmp2
 +    ..\bin\LZMPi.exe -c TestData/Lobster.prg target/compressed_Lobster.prg.cmp2
 +    ..\bin\LZMPi.exe -c TestData/Dinosaur_Disco.prg target/compressed_Dinosaur_Disco.prg.cmp2
 +    ..\bin\LZMPi.exe -c "TestData/Turrican remixed.prg" "target/compressed_Turrican remixed.prg.cmp2"
 +    ..\bin\LZMPi.exe -c TestData/Nintendo.prg target/compressed_Nintendo.prg.cmp2
 +    ..\bin\LZMPi.exe -c TestData/WizballGuitar.prg target/compressed_WizballGuitar.prg.cmp2
 +    dir target\*.cmp2
 +
 +Which equals 13,088 bytes
 +
 +The dictionary compression is 1,343 bytes smaller.
 +
 +
 +
 +=== Demo ===
 +
 +
 +
 +To assemble the demo, first run the command line about in "Example usage" to produce the compressed output files.
 +
 +6502 asm source to decompression is in: asm\DictionaryDecompression.a
 +
 +Demo source (ACME format) is in: asm\Demo.a
 +
 +It can be assembled using: BuildIt.bat
 +
 +Assembled demo prg file is in: target\Demo.prg
 +
 +The dictionary is at $c000 so if you're using a memory viewer it shows when it is read. The compressed data is much lower in memory at around $a50. The decompression address is $8000
  
base/dictionary_compression.txt · Last modified: 2022-08-14 12:10 by martin_piper

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