Compression Unpackers (Prog8)

[badmai]

I was testing different compression methods, maybe useful to someone.

LZSA A2(what the cx-16 uses in kernal)
LZSA A1
LZ4 (used -12 so it's "HC")
RLE - just a standard run length
SAL/ZX0 - used the salavdor compressor

From the screenshot....Times are in jiffies cause i'm not sure about another timing method on the cx16 yet
Load - lower is better, how long to load the data
Size - file size
CRC - of the packed data
Unpack - lower is better, how long did it take to unpack
Check - crc of the unpacked data, should match the "IMAGE.BIN" (60408)

*Screenshot is using sdcard, so should match close to real hardware

Included source code (Prog8), and sdcard version

LOAD"TEST.PRG",8,1
RUN

Links to the great projects this is testing:

LZSA
https://github.com/emmanuel-marty/lzsa/tree/master

LZ4
https://github.com/lz4/lz4

Salavdor
https://github.com/emmanuel-marty/salvador

[desertfish]

- the LZSA decompression is that using the kernal routine or did you write a decompressor for that as well?
- wow that Salvador is super tiny compressed size and very fast decompression!
- I don't see the prog8 source code in the zip file...

[badmai]

Yes that is the kernal routine, why I decided to do these tests, so slow!!

I just downloaded to test, it's in a folder called "PROG8_SRC" ?

yes I should say salvador is the packer, the method is called ZX0

[desertfish]

I was dumb, somehow I glossed over the src folder, dunno why that happened. thanks.

why is the ZX0 one so fast though? in this graph it is only average

https://introspec.retroscene.org/compre ... 210128.png

[badmai]

I'm not sure really this was a 1 sample test, just to test the compressor and unpack some data

if you do some tests make sure you use the "-classic" flag, I missed that and the unpacker was trying to unpack v2

Edit- Give me a few minutes, I'll post all my setting used so we are on the same page....

[badmai]

here are the parameters for each packer I used for testing:

lzsa -f2 -r -m5 image.bin IMAGE.LZA

lz4 -12 image.bin IMAGE.LZ4

lzsa -f1 -r -m5 image.bin IMAGE.LZ1

salvador -classic -v image.bin IMAGE.SAL

[badmai]

revisiting some compression tests...
I compressed some 64x64 @4bit sprite frames trying to decompress real time


Original: 2048 bytes per frame or 16K for all
most frames compressed to under 600 bytes
16384 to 3704 bytes for all frames

Decompress seems to take about 1/2 a frame for a single sprite

note:
I modified the decompress routine to also write to vera memory for the sprite
Since we don't have random access to video memory, a ram buffer is required for the decompressed size
as the buffer is filled, it also fills vera memory

Demo shows 3 sprites animated only using 2K instead of 16K for all frames loaded to VRAM
*You can press ESC to exit demo


Try It Now!

[desertfish]

in the sprite code above, why is there a custom written decompression routine? Can't it use the one built into rom ?

[badmai]

Speed, LZSA1-m5 is alot faster to unpack and I wanted to test the fastest I currently have.
The ROM routine would work fine, just not the fastest option.

[desertfish]

aha it's a different compression format, I didn't notice that.