Stack pointer operation (enables putting putd in `std.porth`)

[ap29600]

A simple operation that pushes a pointer to the element that is currenlty on the top of the stack.

With this functionality it's possible to allocate a temporary buffer on the stack by repeatedly pushing 0, and this enables to implement putd without a static buffer in memory, so putd can now be in the standard library.

As a sidenote, building gol.porth will now fail due to the macro name collision.

There is one drawback, and that is that this will create a discrepancy between simulation and compilation, as there is no easy way to implement this in python I think. Assuming that the stack is contiguous in memory in the bootstrapped version, there should really be no problem after that.

[mjdr]

Stack should be used for storing values that size know in compile time. ref introduces value aliasing and makes static analysis useless

[Domkeykong]

you can alternatively call the mmap syscall and get some memory, this is obviously a bit overkill but unless there isnt any malloc functionality this is the only way to not clobber any memory. Also don forget to call munmap

[ap29600]

yep, makes sense to me.

[mjdr]

here another way you can implement putd without mem

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