mirror of
https://github.com/lscharen/iigs-game-engine.git
synced 2024-06-07 11:29:33 +00:00
136 lines
2.7 KiB
ArmAsm
136 lines
2.7 KiB
ArmAsm
MoveLeft
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clc
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adc StartX ; Increment the virtual X-position
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jsr SetBG0XPos
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lda StartX
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lsr
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jsr SetBG1XPos
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jsr DoFrame
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rts
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MoveRight
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pha
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lda StartX
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sec
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sbc 1,s
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bpl *+5
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lda #0
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jsr SetBG0XPos
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lda StartX
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lsr
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jsr SetBG1XPos
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jsr DoFrame
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pla
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rts
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MoveUp
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clc
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adc StartY ; Increment the virtual Y-position
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jsr SetBG0YPos
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lda StartY
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lsr
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jsr SetBG1YPos
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jsr DoFrame
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rts
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MoveDown
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pha
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lda StartY
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sec
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sbc 1,s
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bpl *+5
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lda #0
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jsr SetBG0YPos
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lda StartY
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lsr
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jsr SetBG1YPos
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jsr DoFrame
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pla
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rts
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; Very simple, scroll as fast as possible
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oldOneSecondCounter ds 2
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frameCount ds 2
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Demo
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lda OneSecondCounter
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sta oldOneSecondCounter
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stz frameCount
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:loop
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lda #1
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jsr MoveLeft
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inc frameCount
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ldal KBD_STROBE_REG
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bit #$0080
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beq :nokey
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and #$007F
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cmp #'s'
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bne :nokey
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pla
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rts
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:nokey
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lda OneSecondCounter
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cmp oldOneSecondCounter
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beq :loop
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sta oldOneSecondCounter
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lda ScreenWidth
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cmp #150
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bcs :loop
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lda #FPSStr
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ldx #0 ; top-left corner
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ldy #$7777
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jsr DrawString
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lda frameCount
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ldx #4*4
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jsr DrawWord
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stz frameCount
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bra :loop
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FPSStr str 'FPS'
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