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From: avery@puff.WISC.EDU (Aaron Avery)
Newsgroups: comp.sys.amiga
Subject: Using the blittler directly
Message-ID: <555@puff.WISC.EDU>
Date: Tue, 17-Mar-87 07:12:50 EST
Article-I.D.: puff.555
Posted: Tue Mar 17 07:12:50 1987
Date-Received: Wed, 18-Mar-87 06:30:35 EST
Distribution: comp
Organization: U of Wisconsin CS Dept
Lines: 18


     I have written a 68000 assembly language program that performs a certain
mathematical algorithm. I realized that there are certain portions of this
algorithm which the blitter can accomplish far more efficiently than the
68000 can. I'd like to modify my program to make use of the blitter, but
so far, I haven't had much luck getting it to do anything. Has anyone out 
there used the blitter directly (using its registers)? Should I disable
interrupts, or will it even make a difference? Could someone please tell
me which direction (left, right) the blitter shifts bits? (I'll eventually
find out by trial and error, but it doesn't hurt to know beforehand)
If anyone can tell me if there are certain ways to make the blitter function
faster (performing the same operation), please let me know. I haven't even
been able to disable interrupts from assembly, either using the DISABLE
macro or otherwise. I think this may be my problem using the blitter, as
I think the copper uses it during the vertical retrace. Thanks.

Aaron Avery ({caip, allegra, seismo, harvard, ihnp4}!uwvax!puff!avery)
	    (avery@puff.wisc.edu)