[ASM & Hex] Encrypt Variable

[Koople]

Hi there,

I've been trying to write values to variables stored in the DMA RAM. I've tried calling 0806e454 to get the address of the variable and then strh to store my desired value, but this doesn't seem to work. Is there a separate store/encrypt variable function? My knowledge of how the DMA memory works is limited.

Thanks.

EDIT: just kidding, my process was correct I just had other bugs in my code.

 

[miksy91]

Hi,

Not sure if I can help, but what are you trying to accomplish exactly? Are you just trying to experiment how DMA transfer in GBA works, or do you think you have an actual need for using it? I would assume that you don't have to use DMA unless you need to load / move lots of data in the ram at the same time.

Also what comes to doing a DMA transfer, I would assume that there is some special instruction, or a set of instructions involved in using it. This is just an assumption, and I haven't really programmed with any assembly language using DMA before, so I don't really know how to use it in GBA.
But I think it would make sense if DMA transfer could be evoked using an instruction like "fetch nn bytes of data from memory address xxyyzzqq (and store them at aabbccdd ?)" at the start of DMA memory (and these nn bytes would eventually land there by the definition of what DMA transfer does). That would after all only require one memory access (= fetching this CPU instruction) rather than several for copying values one by one (= wouldn't really be much more efficient than loading values elsewhere in ram I think).