[fpc-pascal] Coroutines and VirtualAlloc

Michael Van Canneyt michael at freepascal.org
Wed Apr 19 11:49:00 CEST 2017

On Wed, 19 Apr 2017, Sven Barth via fpc-pascal wrote:

> Am 19.04.2017 11:26 schrieb "Ryan Joseph" <ryan at thealchemistguild.com>:
>>> On Apr 19, 2017, at 4:14 PM, Sven Barth via fpc-pascal <
> fpc-pascal at lists.freepascal.org> wrote:
>>> Those functions simply store (setjmp) and restore (longjmp) register
> values (and setjmp also returns the value passed to longjmp if it had been
> reached by a longjmp). Nothing more, nothing less. So while the stack
> register while be changed, the contents on the stack will not.
>> Why doesn’t “i” in my example increment? The value keeps going back to 1
> even after I used += 1 so its like the old copy of the stack before the
> jump got pushed back on top and it started over. I don’t understand how
> assembly works but I thought it would just start over and the state of the
> stack in that function would still be the same as before so I could keep
> adding 1 every pass.
> Ah, I didn't catch that earlier. Probably "i" is kept in a register due to
> optimization. You should check the generated assembler code to be sure.

Glad we responded the same thing :)


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