Hi,
I´m trying to display a pattern in a 1 bitplane screen with the following code found in Amiga Computing Mag but it results in screen garbage and not in a regular pattern as it should be.
I already tried to find the bug but with no luck :angry:
Can someone point what´s wrong in the code that results in the garbage displayed on the screen, please?
Section Screen,code_c
_LVOOpenLib EQU -552
_LVOCloseLib EQU -414
DiwStart EQU $8E
DiwStop EQU $90
DDFStart EQU $92
DDFStop EQU $94
BplCon0 EQU $100
BplCon1 EQU $102
Col0 EQU $180
Col1 EQU $182
BPL1PTH EQU $E0
BPL1PTL EQU $E2
move.l #scr,d0 ;Load address of our screen in d0
move.w d0,pl1l ;Load low scr addr in Copper list
swap d0 ;Swap address in d0
move.w d0,pl1h ;Load high scr addr in Copper list
move.l 4.w,a6 ;ExecBase
move.l #0,d0
lea GfxName,a1
jsr _LVOOpenLib(a6) ;Open GFX library
move.l d0,a1
move.l 38(a1),WB ;Store WB Copper addr
move.l 4.w,a6
jsr _LVOCloseLib(a6) ;Close GFX library
move.l #CopList,$DFF080 ;Load Copper list in Copper
Loop: btst #6,$BFE001 ;Test left mouse button
bne Loop ;If not pressed keep in loop
move.l WB,$DFF080 ;Restore WB Copper
rts
CopList: dc.w DiwStart,$2C81 ;Top left corner of the scr
dc.w DiwStop,$2CC1 ;Bottom right corner scr
dc.w DDFStart,$38 ;Data fetch start
dc.w DDFStop,$D0 ;Data fetch stop
dc.w BplCon0,$1000 ;Set 1 bitplane lo-res scr
dc.w BplCon1,$0 ;No horizontal offset
dc.w Col0,$0 ;Black background color
dc.w Col1,$FFF ;White foreground color
dc.w BPL1PTH ;Bitplane low high word
pl1h
dc.w 0
dc.w BPL1PTL ;Bitplane low word
pl1l
dc.w 0
dc.w $FFFF,$FFFE ;End of copper list
WB dc.l 0
scr dcb.b 8000,$55 ;Block of 8000 bytes of a pattern
GfxName dc.b "graphics.library",0
