Thread: Copying between arrays problem

Hi Guys,
I'm doing a 1Mb memory dump like this:

Code:

for (int i = 0; i < 0x00100000; i++) {
dump[i] = *(chipmemory+i);
} // i

Then I save the 1Mb "dump" array to a file, and the file contains the data I expect.

The problem arises when I try to write data back to the array beginning at the "chipmemory" pointer:

Code:

    unsigned char msga[18] = "SOME MODIFIED DATA";


    int address = 172378;
    for (int i = 0; i < 18; i++) {
    *(chipmemory+address) = msga[i];
    address++;
    } // i

Is this the correct way to write back to an address 172378 bytes
from the "chipmemory" pointer? or is my code broken somewhere else?
Cheers, Art.

Hi,
I'm not trying to write the whole 1Mb back to chipmemory.
Just the string (in this example) starting at address 172378 in chipmemory,
which was it's address in the 1Mb dump.

So the syntax is fine?
It's got me beat then..

I tried this, which is explicit:

Code:

  
   memcpy(chipmemory+172378, msga, 18);
    memcpy(chipmemory+172396, msgb, 25);
    memcpy(chipmemory+172466, msgc, 22);
    memcpy(chipmemory+172488, msgd, 18);

I just keep calling it before and after the disk has loaded.
I might try writing to the memory this way, and then doing the dump again,
but the scroll text isn't changing.

After doing the memcpy to copy the message to the chipmemory, try copying it back to make sure it's really writing to the chipmemory.

Also, it's possible that those locations are only temporarily used for display purposes and the actual locations of those messages could be elsewhere. Have you tried searching for all instances of "AMIGA HAS STARTED" in the chip memory to make sure there isn't another copy somewhere else?

Is chipmemory declared as an array of unsigned char?
If it is, your code looks like it should work.

But if your emulator is emulating ROM, maybe it's refusing to let you write.
Did you declare chipmemory? Or is it in a header provided by the emulator?
It's quite possible to declare ROM writable (not const), but you still can't write it.

Originally Posted by rcgldr

After doing the memcpy to copy the message to the chipmemory, try copying it back to make sure it's really writing to the chipmemory.

Also, it's possible that those locations are only temporarily used for display purposes and the actual locations of those messages could be elsewhere. Have you tried searching for all instances of "AMIGA HAS STARTED" in the chip memory to make sure there isn't another copy somewhere else?

Yeah, I did mention there are no other instances of the messages.
I am dumping the emulated computer's entire RAM.

I have has success with it, but still don't know what I was doing wrong.
I will just save a copy of the working program and hold onto it!