IRQ Installer

[groepaz]

I am curious... is there a practical reason for why this has to be fully relocatable? Or is it just for the challenge?

[chysn]

Anyhow, here's a slightly smaller version, with the roles of X and Y reversed. Interrupts are disabled just around the critical section. The "GetPC" routine probably gets used more than once in a bigger example, so I used $03/$04 as scratch pad - with the offset added to Y:X with TXA and TYA (instead of doing STX $03, STY $04 as yet another temporary store in between):

Yeah, nice!

I was able to shave off one byte by removing

Code: Select all

.2020  8A        TXA

due to this already having been done in the FAC2 routine.

I am curious... is there a practical reason for why this has to be fully relocatable? Or is it just for the challenge?

I'm not sure yet, really. I'm just going to have it around in case something comes up later.

[Mike]

Good morning!

I was able to shave off one byte [...]

Yeah, it was around 1 A.M. local time when I wrote this code. At this time of day, such things inevitably slip through.

...

[chysn]

For me, the difference between a high-level language and machine language is that, in my machine language code, I keep finding optimizations for a much longer time, pretty much whenever I seriously inspect it. I always imagine that there's this perfectly-efficient version of what I want to do that takes flawless advantage of every trick out there, and all the laws of physics and thermodynamics, that I probably wouldn't even recognize as a "program," and that's only half as long as what I wrote.

[groepaz]

Stared at it for a while, looking for an opportunity to shave off another byte with an illegal opcode - but it seems to be quite optimal now

[chysn]

Stared at it for a while, looking for an opportunity to shave off another byte with an illegal opcode - but it seems to be quite optimal now

Thanks for taking a look!

I should take some time to learn the illegal opcodes. My geek buddies and I discovered some of them in middle school, but we never wrote anything down.

[groepaz]

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i have spent a lot of time on researching them and proving/verifying how they work in the past years... i think by now the most complete document on the matter can be found here
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