a chip8 stack implementation
copy until the #tests# secion into your program, removing the stack-buffer label and memory
call push to save registers v0 - vd to the stack
call pop to restore registers v0 - vd from the stack
if you attempt to pop from an empty stack or push to a full stack, you will hit an Octo breakpoint - if your environment does not support these (or you don't care to be warned) then remove lines 50 and 70.
you can allocate as much memory as you want to the stack by
copy/pasting line 25. HOWEVER make sure to increase the stack
size in increments of 14 and be sure to update :stacklimit to
reflect the new size.
in order to save as many registers as possible, register ve is
used as a temporary register to load the stack pointer. This means
that pseudo comparisons (<, <=, >, >=) are unusable to check stack
boundaries. If you attempt to save a fewer number of registers to
the stack manually, you risk jumping over the hardcoded stack
boundaries.
using push and pop is fairly memory intensive, so this won't
perform well on hardware-emulating speeds.
TLDR
- only use push and pop to save registers to the stack
- be prepared to up your emulated cpu cycles