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pal_stack - Introduction to the PAL program stack
The program stack is a dynamically sized data area onto which data units can be pushed and pulled. When a register or index is pushed onto the stack, the next pull will take that item off the stack again. This item is known as the topmost item.
There is one stack per program thread. When functions are called, they will make use of the same program stack as their caller, but an internal lock will be pushed onto the stack that protects data added by the parent function. Upon return from the function, the stack is flushed up to the last internal lock, which is then removed from the stack.
The stack can also be locked programmatically, using the stack/lock command, to prevent a software bug from pulling too many items off the stack. It may also be flushed using the stack/flush command.
Data can be added to and removed from the stack using two methods.
The first, and most efficient method, is to use the special register keyword PUSH in place of a write argument, or PULL and PEEK in place of a read argument. This is described in pal_registers(5).
The second method is to make use of the dedicated stack commands, listed in pal_commands(5).
pal_commands(5), pal_registers(5),
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| PAL 1.0 | pal_stack (5) | 20 February 2007 |