Allocate Memory on Stack

[Shield]

Hello Gents

Does anyone know a way of allocating memory on the stack
in the way the C-function 'alloca' does?

I figure that it's only possible with ASM (if it is even possible without compiler assistance), though I'd very much prefer
something standard like *foo = AllocateStackMemory(16).


Any thoughts are appreciated, thanks.

[Fred]

You should be able to do it with a structure of size 'X' (not tested, but you see the idea):

Code: Select all

Structure StackMemory16
  a.b[16]
EndStructure

Procedure a()
  *mem = @stackmem.StackMemory16
EndProcedure

Combine that with a macro to create your structure automatically depending of the size (if it's a fixed one), and it should be OK.

[Shield]

Oh wow, that's some smart trick.
Maybe with some macro magic I could be able to come up with something.

Thanks, Fred!

[Thunder93]

We often enough have to resort to tricks with PB.

[idle]

might need to resort to asm as it requires a constant or immediate value for the size

Code: Select all

Macro AllocateStackMemory(ptr,_size) 
   Structure stackmem_#_size
     a.a[_size]
   EndStructure
   ptr = @stackmem.stackmem_#_size
EndMacro 

Structure bArray
  a.a[0]
EndStructure   

Procedure foo() 
  Protected *foo.bArray 
  AllocateStackMemory(*foo,16)
  For a = 0 To 15
    *foo\a[a] = a 
  Next 
   For a = 0 To 15 
     Debug *foo\a[a] 
  Next 
EndProcedure   

foo()
foo()