BUG: Inside functions wait until does not work

[ZiwKerman]

To reproduce run the following script

    declare function bugtest1 {

        print "waiting for 3 seconds".
        wait 3.
        print "done!".

        declare t to time:seconds + 5.

        print "waiting until time:seconds > t = time:seconds + 5".
        wait until time:seconds > t.
        print "done 5!".
    }

    bugtest1().

The second wait finishes instantly.

[Dunbaratu]

wait until is implemented as a trigger.

Just to give an idea, here's how complex it is now:

at the top it makes this trigger:

push $time     ------.  <-- $wait-0000003 is a variable with this instruction's address location in it.
push "seconds"       |
getmember            |--- from your expression
push $t              |      "time:seconds < t"
gt             ------'
br.zero 4
endwait  // changes the CPU state back to "Running"
push $wait-0000003  // id of this trigger, i.e. the 3rd trigger the compiler made.
removeytrigger
EOF

Then down in the body where the wait statement actually existed, it turns that trigger on with:

push $wait-0000003 // id of this trigger
addtrigger true  // 'true' means "do turn on the CPU's Wait state".

So it sets the CPU's state to Waiting due to the 'true' parameter to addtrigger, and waits for the trigger to turn it back off again.

What's causing the problem is the fact that the trigger's scope is outside the scope of the function, so it's not allowed to see the functions' variables in its expression check. (it's probably falling back to a more global $t instead of the local one).

I see no reason at all for this to be implemented on the back of the already beleaguered trigger system, with its upper limit on instructions allowed and so on, when you could just do all the logic right there inline in the code like so:

wait 0.0000001
push $time     ------.
push "seconds"       |
getmember            |--- from your expression
push $t              |      "time:seconds < t"
gt             ------'
br.zero -6  // jump negative 6 instructions (up to wait 0.0000001)).

So it basically just spins in a loop forever checking the expression right there in the inline code, but in a way that only loops once per update rather than busy polling.

So much cleaner. Doing this will also solve issue #688, as it is caused by accidentally triggering the "trigger" logic when it should have not done so (using a zero wait makes the system think it's a WAIT UNTIL when it isn't).

[Dunbaratu]

actually I think I got the gt/lt 's backward in my above examples typed out manually, but you get the gist of it.

[Dunbaratu]

Fixed when PR #726 got merged.