Use this encoder : https://www.dangermouse.net/esoteric/lenpeg.html https://www.dangermouse.net/esoteric/lenpeg.html It allows for compression to a negative,

Use this encoder : https://www.dangermouse.net/esoteric/lenpeg.html https://www.dangermouse.net/esoteric/lenpeg.html It allows for compression to a negative, unbounded number of octets. I guess you just have to run it in reverse ?