Saukav is a generalization algorithm from zx7b. Basically is for advanced users,
because the decompression routine is generated by the compressor.

When you compress a file with saukav.exe, a file called d.asm is generated with
the decompression code. For this reason is recommended to process multiple
files in the same command line call. All these files will be compressed with
the same variant.

This generalization contains 2*9*2= 36 different compression codings, each one
can be speed optimized with 5 variants, so a total of 180 decompression routines
are available.

The first parameter is the flow. Can be backward or forward. It's important for
pass the parameters in the routine call. For example if we hava a compressed
buffer at $8000 with lenght $1000 and uncompressed buffer at $4000 with lenght
$1b00, we have this code is flow is forward:

        ld      hl, $8000
        ld      de, $4000
        call    sauk

And this one is flow is backward:

        ld      hl, $8fff
        ld      de, $5aff
        call    sauk

The second parameter is the optimization speed. It's a number between 0 and 4.
It doesn't affect to the compression algorithm. It's only for the size of
the decompressor and the decompression speed.
Lower values means shorter and slower decompression routine. Higher values
accelerate the speed but with a bigger decompressor.

The third parameter is offset encoding. It's a number between 0 and 8. It fixes
the window size for LZ77 algorithm. The generated window is between 256 and 32896
bytes following this formula: window size= 2^(offset+7)+128. Lower values
generally are better for small files and higher values for big files.

The fourth parameter is the gamma function. It's a number between 0 and 1. Basically
you choose between 2 different gamma functions. This function is a fixed huffman
code to assign the length of the matches. Some files compress better with one
gamma function and there is not a generic rule to choose the best one.

The user can choose between the first 2 parameters or fix all parameters. If you
fix only the first 2 parameters (flow and speed), the compressor will try all 18
variations for the other 2 (offset and gamma) and choose the one with offers
better compression ratio for all files you specified. Also you can fix all 4
parameters, but not necessarily you'll choose the best algorithm.

For example when you call with these parameters:

saukav b1o4g0 inputfile.ext

You'll have exactly the same zx7b variant. That's the generated inputfile.ext.skv is
the same file that zx7b generates.

But it's recommended to fix only flow and speed. This way your results will be better.
Remember use the same call if you plan to uncompress different files with the same
code:

saukav f2 input1.scr input2.scr input3.scr

Then in your code you'll have something like:

        ld      hl, pfile1
        ld      de, $4000
        call    sauk
        call    pause
        ld      hl, pfile2
        ld      de, $4000
        call    sauk
        call    pause
        ld      hl, pfile3
        ld      de, $4000
        call    sauk
...
        include "d.asm"
pfile1: incbin  "input1.scr.skv"
pfile2: incbin  "input2.scr.skv"
pfile3: incbin  "input3.scr.skv"

I recommend use first zx7b. Switch to saukav only when you have some experience with zx7b.

Created by Antonio José Villena Godoy, 2017
Creative Commons Licensed by SA
https://creativecommons.org/licenses/by-sa/4.0/legalcode