Problem with memcopy

BlitzMax Forums/BlitzMax Programming/Problem with memcopy

ImaginaryHuman

(Posted 2004) [#1]

Why doesn't Blitz compile this piece of my program, complaining on the memcopy line with the following error?:::

Compiling:BounceTestGravity.bmx
Compile Error:Unable to convert from 'Int' to 'Byte Ptr'
[/Applications/BlitzMaxSetup100/PaulsTests1/BounceTestGravity.bmx;103;5]
Build Error: failed to compile /Applications/BlitzMaxSetup100/PaulsTests1/BounceTestGravity.bmx

psource is defined with Local psource:Byte Ptr initialized with PixmapPixelPtr(img,0,0) which is a pixmap. psize is an integer size in bytes:

	txtrp:TPixmap=LockImage(txtri,0,True,True)
	Local pdest:Byte Ptr
	pdest=PixmapPixelPtr(txtrp,0,0)
	MemCopy(pdest,psource,psize)        ' problem with this!
	UnlockImage(txtri)
	DrawImage txtri,objpos[o,0],objpos[o,1]

I'm trying to do a direct memory copy from the pixel data of a regular pixmap (in memory) to the pixel data of a locked image's pixmap in video ram. If I change the memcopy to a nested for-next loop for x and y, using writepixel and readpixel, it works, but what's wrong with the memcopy line?

ImaginaryHuman

(Posted 2004) [#2]

Update ... I've found that the main problem in the entire program was using Global to define the psize variable.

Global psize:int=wid*hig*4

causes the later call to MemCopy to bomb out. None of the code is inside functions or similar, so in general the psize variable doesn't need to be global.

So I changed it to

psize:int=wid*hig*4

and it compiled and everything worked.

Of course that is after 10 million attemps to write alternative copying routines.

Hotcakes

(Posted 2004) [#3]

So... -why- didn't it like it being a Global?

ImaginaryHuman

(Posted 2004) [#4]

That I don't know. This is a pretty simple program, there are no functions so basically all the variables should be accessible to all the program. I used some Local variables for speed but those are fine, so maybe it's a bug? Setting some of the variables to global and accessing them from within the same context (ie not within a function) seems to turn the variable into 0 instead of holding the correct value.