Calculate the memory and t-states that Z80 code takes

So …

I’ve been writing quite a bit of code of late (and certainly no blog posts). I’ve been focusing on getting my display update code as efficient as possible. So I wanted to examine my code to see what the space/time trade-off was in terms of memory consumption and number of processor cycles used.

I talked a little about space/time trade-offs in an earlier post on calculating screen positions, in that post I manually calculated the t-states using a document I found online.

When I was writing production Z80 code my old assembler (OCP’s Full screen editor assembler) used to be able to output the information that I needed as part of the assembly process. A quick look at my current tooling shows it doesn’t give me the functionality I need.

Of course then …

I went to work and wrote an online z80 t-state analyser.

I have included as many of the undocumented Z80 instructions that I am aware of and have run it against several large online code bases (manic miner etc) and it handles them without issues.

It’s easy to use, paste in your z80 assembly code and it’ll automatically process it. Give it a go and let me know if it’s of any use (If you see any red lines, please let me know as that’s an unrecognised instruction).

I’m looking to extend the app to produce syntax highlighted code with t-states for use in blogs and articles. if you think that’s a decent idea, or have features you’d like to see then contact me via twitter or discord.

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