pucrunch

A fork of pucrunch which includes source for unpacking on the BBC Micro.

Packing your data

Once the executable is built, packing your data down is very easy and is achieved from the command line:

./pucrunch -d -c0 -l0x900 -s BIN/SOURCE.DAT BIN/DEST.DAT

The few flags of note here are -l which tells it the address to unpack to, and -c0 to tell the cruncher we're not on a C64!

Unpacking your data

Now the data is packed, you'll need to include the decruncher into your sources, which I've modified to assemble under BeebASM; see uncrunch-bbc.asm. Then all that remains is for you to unpack the data.

The routine will unpack to the address specified on the cruncher command line, but that's just a few bytes into the header data so should be easy enough to change on the fly.

For example, to unpack the data we packed in the command line above:

ORG &70
.LZPOS	EQUW &9e	; 2 ZeroPage temporaries
.bitstr	EQUB &fb	; 1 temporary (does not need to be ZP)

ORG &1900
{
.start:
    CLC
    LDX #HI(packedData+2)
    LDY #LO(packedData+2)
    JSR unpack
    BCC unpackOK
    
    ; If C flag set, there has been an error
    LDA #70
    JSR &FFEE
    JSR &FFE7
    RTS
    
    ; At this stage 0x900 will contain our unpacked data!
.unpackOK:
    LDA #48
    JSR &FFEE
    JSR &FFE7
    RTS
.end:
}

INCLUDE "uncrunch-bbc.asm"

.packedData:
INCBIN "BIN/DEST.DAT"

Summary

pucrunch is a handy little cruncher for 8 bit micros and is very easy to use. I've not investigated the options too much on the crunching side of things but for my purposes it's been very useful.