How to implement alloc() in Delphi?

Question

How can I implement a stack allocation method alloc() using assembly in Delphi? It isn't even exported from msvcrt.dll the way malloc/free is.

For a start, details matter. The function is called `alloca`. Be precise. Get some ideas on how to do it from the code in Grids.pas, perhaps named StackAlloc IIRC, which I probably don't. It's dangerous to do this though. Easy to stomp on the compiler. Are you sure you need to do it. — David Heffernan, Oct 18 '15 at 11:26
@DavidHeffernan Are you sure that's the same method as the one found in GCC, MSVC? The one in Delphi requires free. But the `alloca` doesn't. — user15124, Oct 18 '15 at 11:29
@DavidHeffernan These are not the same methods. `StackAlloc` in Delphi requires `StackFree` yet the `alloca()` in C++ doesn't. — user15124, Oct 18 '15 at 11:33
I thought you wanted to allocate memory on the stack. Was I wrong? In any case, I think calling StackFree is optional. — David Heffernan, Oct 18 '15 at 11:33

score 1 · Accepted Answer · edited May 23 '17 at 12:14

1

There is a functioning implementation of StackAlloc in the graphics32 library. This supports x86 and x64 targets.

I learned this from a websearch which took me here: How to use StackAlloc in x64?

The other well known implementation that I am aware of can be found in the Grids unit of the VCL.

edited May 23 '17 at 12:14

Community

answered Oct 18 '15 at 11:33

David Heffernan

1 Answers1