Path: utzoo!utgpu!news-server.csri.toronto.edu!cs.utexas.edu!sdd.hp.com!mips!pacbell.com!tandem!zorch!amiga0!mykes From: mykes@amiga0.SF-Bay.ORG (Mike Schwartz) Newsgroups: comp.sys.amiga.programmer Subject: Re: Block Moves Blits Message-ID: Date: 30 Jun 91 20:52:53 GMT References: Organization: Amiga makes it possible Lines: 35 In article peterm@am.dsir.govt.nz (Peter McGavin) writes: >In article >Mike Schwartz writes: >>Qblit forces you to reload the blitter registers over and over > >Nope. One call to QBlit() can perform multiple blits, and you need only >reload the registers that change for the 2nd and subsequent blits. See >the description of "function" on page 380 of the 1.3 L&D RKM. > >>Also, again, you need to do OwnBlitter() if you want to keep the blitter >>registers loaded with the numbers you want. > >Again, nope (if you use QBlit() right). > >Furthermore, QBlit() has the advantage of not blocking your task when >someone else already owns the blitter. So it is easier to keep both the >CPU and blitter busy at the same time with QBlit() than with OwnBlitter(). >-- >Peter McGavin. (srwmpnm@wnv.dsir.govt.nz or peterm@am.dsir.govt.nz) No matter what the RKM says, QBlit() doesn't perform as you indicate. It clearly states in my RKM that QSBlit() overrides the QBlit fifo, meaning that your blitter registers could be trashed. It also isn't clear from the RKM whether someone else can do an OwnBlitter() and get the blitter in the midst of QBlitting. In the many areas where the RKM isn't clear like this, CBM seems to indicate that you shouldn't rely on the behavior of the OS routines... In other words, if you assume that the blitter registers are going to be the same as when you last QBlitted a plane, your code might work on YOUR machine with YOUR applications, but not on mine. -- **************************************************** * I want games that look like Shadow of the Beast * * but play like Leisure Suit Larry. * ****************************************************