Re: [AD] Exorcising END_OF_MAIN for Allegro 5

["Peter Hull" <peterhull90@xxxxxxxxxx>]

Just one snag-ette - no ucontext on OS X! (it may be in 10.5, it isn't
in 10.4). Actually ucontext is defined but no make/swap/getcontext.
This is despite it being a BSD function.

More thought required!

Pete


On Mon, Jul 14, 2008 at 1:06 PM, Peter Wang <novalazy@xxxxxxxxxx> wrote:
> No, that should work.  When thread_func resumes into main, it will be
> running on main's original stack.  hijacker runs on the stack st2.
> Which leaves the stack allocated by pthread_create() wasted...
>
> Peter
>
> On 2008-07-14, Peter Hull <peterhull90@xxxxxxxxxx> wrote:
>> I'll try it. I'm not a ucontext expert either!  I think you'd need to
>> copy main's stack into the new thread first (is this possible?)
>> otherwise something like the following would fail.
>> int main()
>> {
>>  int myvar = 99;
>>  al_init();
>>  do_something_with(my_var); // crash because it's gone..!
>>  return 1;
>> }
>>
>> Pete
>>
>> On 7/14/08, Peter Wang <novalazy@xxxxxxxxxx> wrote:
>> > On 2008-07-14, Peter Hull <peterhull90@xxxxxxxxxx> wrote:
>> > > On 7/14/08, Peter Wang <novalazy@xxxxxxxxxx> wrote:
>> > > > The problem used to be that one of the Mac libraries needed to take over
>> > > > the main thread, so we had to relegate the user's code to another
>> > > > thread.  I hope it has changed.
>> > > Right, the OS will only deliver events to the main thread but in
>> > > Allegro 4 there was nowhere in the user's code where we could reliably
>> > > receive and dispatch the events. Magic main is used to run the user's
>> > > main() in a second thread. A5 uses the same design at the moment. We
>> > > could get around this if we require the user to call al_wait_for_event
>> > > regularly (which I think is not the current case) or figure out some
>> > > way to return from al_init but in a different thread (longjmp,
>> > > ucontext or similar)
>> >
>> > This is an interesting idea!
>> >
>> > Can you do something with the attached code?  This is the first time I've used
>> > ucontext so it's probably not 100% correct.  I get this output:
>> >
>> >    main entered in [b7e4e6c0]
>> >    thread_func in [b7e4db90]
>> >    main resumed in [b7e4db90]
>> >    hijacker in [b7e4e6c0]
>> >
>> > Peter
>
>
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