| User | Post |
HyperLamer
Posts: 6493/8210 |
But that's not one byte. |
MathOnNapkins
Posts: 2136/2189 |
Oh yeah? I've seen jump tables that are generated with RTS:
REP #$30
LDA INDEX
ASL A
TAY
LDA JUMPTABLE, Y
PHA
SEP #$30
RTS
very hard to spot from just casually looking at a routine. |
HyperLamer
Posts: 6480/8210 |
Returning jumps don't count!  |
MathOnNapkins
Posts: 2134/2189 |
Sure they will... (RTS), (RTI), (RTL). You just won't like the result |
HyperLamer
Posts: 6453/8210 |
It's also useful when you need to remove a single opcode. Jumps won't fit in one byte.  |
MathOnNapkins
Posts: 2131/2189 |
If you ask me, NOP is a waste of space
While you are more or less correct, there are some things that you simply must use a NOP for on an snes. If you want to do hardware divide or multiply, for instance, you have to wait a set number of cycles to get the result back from the onboard circuitry. So if you have to wait 8 cycles, you will use 4 NOPs, since they take 2 cycles a piece. |
FloBo
Posts: 83/101 |
thnx, bio^^ |
Bio
Posts: 125/458 |
he being refeiring to 65c816 oppcode tutorial
here a link
http://freewebtown.com/illegalmove/65816ref.hlp |
FloBo
Posts: 82/101 |
It's always just a few bytes to be filled, so it won't make the whole thing too slow... also i needed it just for a tiny self-written little tool that does all that filling automatically... calculating the next jump-to position would be a too much effort for the little advantage you may get. Anyway, thanks for your help, Gideon
@ice man: what document are you talking about? jay's asm-tutorial?! |
Setzer
Posts: 416/532 |
If you ask me, NOP is a waste of space  just JMP to the address you need it to go too, it sounds alot simpler to me, and alot more efficient. unless, say, you only have a few bytes that you'd have to bypass. |
Gideon Zhi
Posts: 52/79 |
Another option, if there's a _lot_ of space you're NOPing through, is to add in a Branch Always or a JMP to the address of the next executed instruction. Your game'll execute faster with one JMP or a BRA rather than ten NOPs |
ExKay
Posts: 926/1114 |
Nope, d4s once told me that EA is a NOP and seeing that I have an 65c816 reference with all the opcodes, that's why I knew that. |
FloBo
Posts: 81/101 |
Heyhey^^ It works!! Many thanks to you, Ice Man Dankeschön!!!
Well, then how do you know about this? Did you use your holidays to learn ASM? |
ExKay
Posts: 924/1114 |
Nope, I never posted something about ASM.
Jedenfalls, kein Problem. |
FloBo
Posts: 80/101 |
I'll try this... thnx.
btw, it was you who posed this question already, wasn't it? |
ExKay
Posts: 923/1114 |
Change the hex address to EA, it's a NOP which means No Operation and won't execute the code. |
FloBo
Posts: 79/101 |
Hey there. I think there's been a thread like this some time ago but I actually can't seem to find it anymore...
Anyway here's my question: I have some space left within my SNES-rom and want to fill it with some hex-characters (for I don't want to rewrite all pointers coming afterwards...). The problem is, that they're all read as asm-instructions by the snes.... So is there any asm-instuction (and the according hex-value) that simply doesn't do ANYTHING???
Thanx in advance, FloBo... |
hukka
