Hiscore name packing...Save the CD32's NVRAM!

[mcgeezer]

I came up against this before and put it on the back burner, basically I'm after the fastest (time to develop or acquire) a packer/unpacker that will crunch a hiscore table.

The table is structured simply like this:

RECORD_TABLE:	rept	MAX_LEVELS		
		dc.b	"LEO",$ff		; 0 = level number, only anything >0 is saved = 0 is default in game.
		dc.w	0                      ; record lap time
		dc.w	0                      ; record track time
		endr

There are 32 levels... so that is 32*8 = 256 bytes which needs 26 NVRAM blocks..

In CD32 terms this means that is a quarter of the NVRAM.

In terms of the data, there's only 37 combinations in the name (A-Z 0-9 <SPACE CHAR> )
In the record lap and track times, these are frame ticks... so they probably won't go above 10 bits each.

Are there any simple packers I can use to pack the table down, or am I looking at rolling my own (which will be a pain in the arse)? Or should this be the latest coding challenge to reduce it as much as possible. wink wink

Cheers,
Geezer

[StingRay]

First thing I'd try is using one of the available crunchers (such as CrunchMania) to see how much they crunch that kind of data. If crunching ratio is good enough, only thing needed is adding the decruncher code. Decrunching should be done very quick as the file isn't large.

If crunching ratio is not good, one can still think of alternative solutions.

[DanScott]

I wouldn't actually use a packer to pack it, as you just can't guarantee the entropy of that kind of data.

It's probably worth just trying to store the data as a bit stream in as few bits as possible

[jotd]

as Dan said. Encode/decode the data as a bitstream with only used bits. Easy with masks & shifts (as you already know).

Then try to pack it using any available packer, and if the size is smaller, use the packed version else use the unpacked version.

(if you have only one player and the name is the same, the packing will save data )