Question about P96 bitmap locking but mostly about timer.device

[hceline]

I'm trying to fix an old program that accesses graphics memory on RTG without taking any locks.
I've read the autodocs for both ChyberGraphics and Picasso96 and found lots of code examples.
But none of the examples I can find has any error-handling if they fail to acquire the lock.
Either they they just skip the whole operation on the bitmap, or they just do their thing anyway with cached pointers or other dubious tricks.
In the program in question I got a routine that can't do the former. It would make for a bad user experience as it's handling bitmap dragging with mouse.

I automatically went for a while-loop as in the following pseudo-code.

lock=LockBitmap()
while(not lock)
    {
    Delay(SomeTime)
    lock=LockBitmap()
    }
DoWork()
UnlockBitmap(lock)

But I lack the information needed to decide on the length of "SomeTime" and the choice of Delay()/TimeDelay() and eventually what timer.device UNIT to use in this case.
I do not want "SomeTime" to be unrealistically short, wasting cycles banging the lock to often. But I also want it short enough that the user-interface does not feel unnecessarily laggy if the lock fails.
If my window is open on "Workbench Screen" on a lightly loaded system and I'm maximally unlucky, trying the lock just as the OS/P96 has made a blocking lock, how long must I expect to wait? And what is the best delay-function/timer-source for this case? Anything else I'm missing?

-Hagbard Celine

[Thomas Richter]

Originally Posted by hceline

But none of the examples I can find has any error-handling if they fail to acquire the lock.

There is not really much to handle. If locking fails, then because the bitmap is not a P96 bitmap - the call itself blocks until the bitmap is available. Hence, error handling should just avoid drawing to anything because that "anything" passed in was nothing the function would be able to handle in first place and you cannot render on either.


Thus, a single "if" would be sufficient. If the lock is NULL, do not do anything.

[hceline]

Ok, thank you.