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CODE1b
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1989-01-01
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906b
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31 lines
SPEEDY BOBS
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1) The first area you should
concentrate on optimising is the screen
clear routine. How you may ask, I use
the blitter so isnt that fast enough?
Well the blitter when clearing areas
only uses one channel, thus most of the
processor time is left free. This is
often used to perform lengthy
calculations with the processor whilst
the blitter is busy, during which time
the processor runs at almost top speed.
We can also use this time to clear part
of the screen with the processor. The
fastest way is to use a MOVEM.L
instruction
eg. Suppose the blitter is clearing
the top part of the screen, and a0
points to its start
Lea Screensize(a0),a0
Movem.l d0-d7/a1-a6,-(a7)
Movem.l Blank(pc),d0-d7/a1-a6
Movem.l d0-d7/a1-a6,-(a0)
......................... n times
Movem.l d0-d7/a1-a6,-(a0)