WTW101@PSUVM.BITNET (Bill Warner) (08/10/89)
I am copying a portion of a screen by first finding the BitMap structure of the
active screen and then Bliting it wo my own BitMap structure. I have a few
questions:
(1) Is the function BltBitMap syncronous or asyncronous? Does it call
WaitBlit?
(2) Assuming the screen I am copying is not static, would it be proper to
call Disable() or Forbid() ?
(3) When the OS is writing to the blitter, does it turn off interrupts?
I am afraid of the following: I call Disable, then BlitBitMap. But just
before I call Disable, some task starts to use the Blitter. Now when I call
BlitBitMap it waits for another task to complete its blitter operation (which
will never happen).
Chris
CJC@psuecla (bitnet)rokicki@polya.Stanford.EDU (Tomas G. Rokicki) (08/11/89)
WTW101@PSUVM.BITNET (Bill Warner) writes: > (1) Is the function BltBitMap syncronous or asyncronous? Does it call > WaitBlit? It's syncronous in that it starts by the time the call returns, but it's async in that it isn't necessarily finished by that time . . . > (2) Assuming the screen I am copying is not static, would it be proper to > call Disable() or Forbid() ? Not to my knowledge. > (3) When the OS is writing to the blitter, does it turn off interrupts? No, not to my knowledge. > I am afraid of the following: I call Disable, then BlitBitMap. But just > before I call Disable, some task starts to use the Blitter. Now when I call > BlitBitMap it waits for another task to complete its blitter operation (which > will never happen). Your fears are grounded. -tom
jesup@cbmvax.UUCP (Randell Jesup) (08/12/89)
In article <11248@polya.Stanford.EDU> rokicki@polya.Stanford.EDU (Tomas G. Rokicki) writes: >WTW101@PSUVM.BITNET (Bill Warner) writes: >> (2) Assuming the screen I am copying is not static, would it be proper to >> call Disable() or Forbid() ? > >Not to my knowledge. What you want to do is lock the layers associated with that screen. Read the chapter on layers in the RKM. You should NOT do a disable or forbid. -- Randell Jesup, Keeper of AmigaDos, Commodore Engineering. {uunet|rutgers}!cbmvax!jesup, jesup@cbmvax.cbm.commodore.com BIX: rjesup Common phrase heard at Amiga Devcon '89: "It's in there!"