svanteb@sluga.UUCP (Svante Berglund) (12/02/88)
Is it anyone out there who knows how the blitter nasty function works.
Me and a friend are making some games for the amiga,but when we tried to
speed up the games by turn on blitter nasty,we didn't see any change
at all.
In the hardware manual it say's that if you turn on blitter nasty,the
processor will have no(almost) time at all,and if that's true then
we wouldn't have to do a Blitter-Ready-Loop before starting with the
next bitplane.
I would really appreciate if anyone could answer...............
reply,mail or send a letter to:
Svante Berglund
Sorvagen 10
780 24 Idkerberget
SWEDEN.
joke of today(Is it a bird,Is it a plane,No It's a Pershing Missile heading
for FREEDOM.....)......greetings from BAAL THE GOD............rokicki@polya.Stanford.EDU (Tomas G. Rokicki) (12/03/88)
Is it anyone out there who knows how the blitter nasty function works. Me and a friend are making some games for the amiga,but when we tried to speed up the games by turn on blitter nasty,we didn't see any change at all. Normally, the blitter runs essentially full-out, unless the processor has been blocked from a memory access for so many consecutive cycles (3?), in which case the processor is given a single cycle. The nasty mode just makes sure the processor doesn't even get these cycles. In the hardware manual it say's that if you turn on blitter nasty,the processor will have no(almost) time at all,and if that's true then we wouldn't have to do a Blitter-Ready-Loop before starting with the next bitplane. Not really true; many blitter functions (line draw and many `normal' blits) don't use all possible DMA cycles. Line draw, for instance, does a single read and a single write every four possible memory cycles. The processor could get in on the other cycles. A blitter-ready loop would only be unnecessary if the blitter were in a mode where all possible DMA cycles are taken (a three-source one-destination blit, for instance), blitter nasty was used, and the processor was doing fetches from CHIP RAM. In other words, almost never, and I would certainly never recommend it. -tom