> Allocate one magic number for "start line with space" another for "start line with asterisk" then any other number means this many of the current character and then swap character.

The galaxy brain move would be to always arbitrarily start with one character, replace the two special numbers with a single "don't output any characters, just swap" number, and then... congratulations, you just reinvented CompuServe RLE!

http://fileformats.archiveteam.org/index.php?title=CompuServ...