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1 user currently in Rom Hacking:  hukka |
| Acmlm's Board - I2 Archive - Rom Hacking - another ASM-question... |
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FloBo Koopa Level: 17  Posts: 79/101 EXP: 20723 For next: 4020 Since: 09-11-04 Since last post: 3 days Last activity: 13 hours |
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| 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...  |
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ExKay Somebody set up us the bomb! Level: 50 Posts: 923/1114 EXP: 908268 For next: 39049 Since: 03-15-04 From: Hannover, Germany Since last post: 14 hours Last activity: 1 hour |
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Change the hex address to EA, it's a NOP which means No Operation and won't execute the code.  |
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FloBo Koopa Level: 17 Posts: 80/101 EXP: 20723 For next: 4020 Since: 09-11-04 Since last post: 3 days Last activity: 13 hours |
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| I'll try this... thnx. btw, it was you who posed this question already, wasn't it? |
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ExKay Somebody set up us the bomb! Level: 50 Posts: 924/1114 EXP: 908268 For next: 39049 Since: 03-15-04 From: Hannover, Germany Since last post: 14 hours Last activity: 1 hour |
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Nope, I never posted something about ASM.  Jedenfalls, kein Problem. |
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FloBo Koopa Level: 17 Posts: 81/101 EXP: 20723 For next: 4020 Since: 09-11-04 Since last post: 3 days Last activity: 13 hours |
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| 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? |
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ExKay Somebody set up us the bomb! Level: 50 Posts: 926/1114 EXP: 908268 For next: 39049 Since: 03-15-04 From: Hannover, Germany Since last post: 14 hours Last activity: 1 hour |
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| 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. |
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Gideon Zhi Red Tektite Level: 13  Posts: 52/79 EXP: 10265 For next: 2 Since: 04-02-05 Since last post: 47 days Last activity: 2 days |
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| 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 |
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Setzer Popo Level: 36  Posts: 416/532 EXP: 290182 For next: 17928 Since: 04-22-04 From: Not Florida. because I'm going to sink it. Since last post: 5 hours Last activity: 48 min. |
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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. |
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FloBo Koopa Level: 17 Posts: 82/101 EXP: 20723 For next: 4020 Since: 09-11-04 Since last post: 3 days Last activity: 13 hours |
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| 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?! |
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Bio Buster Beetle Level: 27  Posts: 125/458 EXP: 107144 For next: 9015 Since: 07-06-05 From: a laboratory somewhere... Waiting to be completed Since last post: 8 hours Last activity: 5 hours |
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| he being refeiring to 65c816 oppcode tutorial here a link http://freewebtown.com/illegalmove/65816ref.hlp |
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FloBo Koopa Level: 17 Posts: 83/101 EXP: 20723 For next: 4020 Since: 09-11-04 Since last post: 3 days Last activity: 13 hours |
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| thnx, bio^^ | |||
MathOnNapkins Math n' Hacks Level: 67  Posts: 2131/2189 EXP: 2495887 For next: 96985 Since: 03-18-04 From: Base Tourian Since last post: 1 hour Last activity: 32 min. |
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| 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. |
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HyperLamer <||bass> and this was the soloution i thought of that was guarinteed to piss off the greatest amount of people Sesshomaru Tamaranian Level: 118 Posts: 6453/8210 EXP: 18171887 For next: 211027 Since: 03-15-04 From: Canada, w00t! LOL FAD Since last post: 2 hours Last activity: 2 hours |
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| It's also useful when you need to remove a single opcode. Jumps won't fit in one byte. |
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MathOnNapkins Math n' Hacks Level: 67 Posts: 2134/2189 EXP: 2495887 For next: 96985 Since: 03-18-04 From: Base Tourian Since last post: 1 hour Last activity: 32 min. |
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| Sure they will... (RTS), (RTI), (RTL). You just won't like the result |
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HyperLamer <||bass> and this was the soloution i thought of that was guarinteed to piss off the greatest amount of people Sesshomaru Tamaranian Level: 118 Posts: 6480/8210 EXP: 18171887 For next: 211027 Since: 03-15-04 From: Canada, w00t! LOL FAD Since last post: 2 hours Last activity: 2 hours |
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| Returning jumps don't count! |
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MathOnNapkins Math n' Hacks Level: 67 Posts: 2136/2189 EXP: 2495887 For next: 96985 Since: 03-18-04 From: Base Tourian Since last post: 1 hour Last activity: 32 min. |
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| 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. |
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HyperLamer <||bass> and this was the soloution i thought of that was guarinteed to piss off the greatest amount of people Sesshomaru Tamaranian Level: 118 Posts: 6493/8210 EXP: 18171887 For next: 211027 Since: 03-15-04 From: Canada, w00t! LOL FAD Since last post: 2 hours Last activity: 2 hours |
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| But that's not one byte. |
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