Commodore Amiga - Page 69

·
,
i Fill bit-plane with $FFOOFFOO to produce strzpes
MOVE.L #$21000,Al
MOVE.L
#$FFOOFFOO,DO
MOVE.W #2000,Dl
LOOP:
MOVE.L DO,(Al)+
SUBQ.W
#l,Dl
BNE
LOOP
,
i Set up Copper list at $20000
MOVE.L
LEA
CLOOP: MOVE.L
CMPI.L
BNE
,
#$20000,Al
COPPERL,A2
(A2),(Al)+
#$FFFFFFFE,(A2)+
CLOOP
i Point Copper at Copper list
-,
MOVE.L
MOVE."V
i Start DMA
,
MOVE.W
BRA
#$20000,COPILCH(AO)
COP JMP1 (AO),DO
#$8380,DMACON(AO)
i This is the data for the Copper list.
COPPERL:
DC.W
DC.W
DC.W
$OOEO,$0002
$OOE2,$1000
$FFFF ,$FFFE
iPoint at beginning of bit-plane
i We will write $FFOOFFOO long words
j 2000 long words = 8000 bytes
i Write a long word
iDecrement counter
iLooP until-bit-plane is filled
iPoint
at Copper list destination
jPoint
A2 at Copper list data
iMove a word
iCheck for last longword of Copper list
iLooP until entire copper list is moved
i Write to Copper location register
iForce
copper to $20000
iEnable bit-plane and Copper DMA
;
Go do next task
iMove $0002 to address $OEO
i (BPL1PTHj
jMove $1000 to address $OE2
j (BPL1PTLj
jEnd
of Copper list
Th.e second example sets up a high-resolution, interlaced display with one bit-plane. The
equates are the same as the previous example so they aren't repeated here.
LEA CUSTOM,AO
jAddress of custom chips
56 Playfield Hardware