09-15-2011, 09:59 AM
boriel Wrote:I have heard of using PUSH to POKE memory faster (supossedly faster than LD (HL), ... sequence).
Oh certainly, yes - if you look at some of the other stuff I've done, I've used it. The 2X2 tile print thing was done that way, as was one version of fourspriter. It's got potential.
This routine optionally uses xor to do OVER1 printing, which you need to use to put down multiple characters. I suppose you could build all the blocks in a buffer, but push/pop is best for a linear copy (similar to ldir - pop from one place, then push to another. If the stack pointer goes the right way, that helps too. Have to remember that half of the sequence it probably goes backwards. I think some people have even had data stored in reverse order to work with this.
Anyway, push doesn't really play nicely with AND/OR/XOR of data, so probably not the best choice for this routine. Works well for anything that doesn't mind what it over writes, and for anything that fits perfectly into character squares as well. So long as they are 2 bytes (or multiple of 2) wide! (push is 16 bits).