mirror of
https://github.com/lscharen/iigs-game-engine.git
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Add routine to do horizontal displacement of BG1
This commit is contained in:
Lucas Scharenbroich
parent
c5eb84ea37
commit
9cdba9a537
@ -1,37 +1,37 @@
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; Initialization and setup routines for the second background
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; Initialization and setup routines for the second background
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_InitBG1
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_InitBG1
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jsr _ApplyBG1YPos
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jsr _ApplyBG1YPos
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jsr _ApplyBG1XPos
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jsr _ApplyBG1XPos
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rts
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rts
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SetBG1XPos
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SetBG1XPos
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cmp BG1StartX
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cmp BG1StartX
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beq :out ; Easy, if nothing changed, then nothing changes
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beq :out ; Easy, if nothing changed, then nothing changes
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ldx BG1StartX ; Load the old value (but don't save it yet)
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ldx BG1StartX ; Load the old value (but don't save it yet)
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sta BG1StartX ; Save the new position
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sta BG1StartX ; Save the new position
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lda #DIRTY_BIT_BG1_X
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lda #DIRTY_BIT_BG1_X
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tsb DirtyBits ; Check if the value is already dirty, if so exit
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tsb DirtyBits ; Check if the value is already dirty, if so exit
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bne :out ; without overwriting the original value
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bne :out ; without overwriting the original value
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stx OldBG1StartX ; First change, so preserve the value
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stx OldBG1StartX ; First change, so preserve the value
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:out rts
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:out rts
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SetBG1YPos
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SetBG1YPos
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cmp BG1StartY
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cmp BG1StartY
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beq :out ; Easy, if nothing changed, then nothing changes
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beq :out ; Easy, if nothing changed, then nothing changes
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ldx BG1StartY ; Load the old value (but don't save it yet)
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ldx BG1StartY ; Load the old value (but don't save it yet)
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sta BG1StartY ; Save the new position
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sta BG1StartY ; Save the new position
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lda #DIRTY_BIT_BG1_Y
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lda #DIRTY_BIT_BG1_Y
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tsb DirtyBits ; Check if the value is already dirty, if so exit
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tsb DirtyBits ; Check if the value is already dirty, if so exit
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bne :out ; without overwriting the original value
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bne :out ; without overwriting the original value
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stx OldBG1StartY ; First change, so preserve the value
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stx OldBG1StartY ; First change, so preserve the value
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:out rts
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:out rts
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; Everytime either BG1 or BG0 X-position changes, we have to update the direct page values. We
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; Everytime either BG1 or BG0 X-position changes, we have to update the direct page values. We
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@ -41,248 +41,344 @@ SetBG1YPos
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;
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;
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; Note: This routine can be optimized as an unrolled loop of PEI instructions
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; Note: This routine can be optimized as an unrolled loop of PEI instructions
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_ApplyBG1XPos
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_ApplyBG1XPos
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lda BG1StartX
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lda BG1StartX
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jsr Mod164
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jsr Mod164
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sta BG1StartXMod164
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sta BG1StartXMod164
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lda #162
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lda #162
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sec
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sec
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sbc StartXMod164
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sbc StartXMod164
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bpl *+6
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bpl *+6
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clc
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clc
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adc #164
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adc #164
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clc
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clc
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adc BG1StartXMod164
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adc BG1StartXMod164
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cmp #164
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cmp #164
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bcc *+5
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bcc *+5
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sbc #164
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sbc #164
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tay
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tay
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phd ; save the direct page because we are going to switch to the
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phd ; save the direct page because we are going to switch to the
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lda BlitterDP ; blitter direct page space and fill in the addresses
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lda BlitterDP ; blitter direct page space and fill in the addresses
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tcd
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tcd
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ldx #162
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ldx #162
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:loop
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:loop
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tya
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tya
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clc
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clc
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adc affine,x
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adc affine,x
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sta 00,x ; store the value
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sta 00,x ; store the value
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dey
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dey
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dey
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dey
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bpl :nowrap
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bpl :nowrap
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tya
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tya
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clc
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clc
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adc #164
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adc #164
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tay
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tay
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:nowrap
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:nowrap
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dex
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dex
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dex
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dex
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bpl :loop
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bpl :loop
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pld
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pld
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rts
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rts
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affine ds 164
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affine ds 164
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; Pass accumulator to set every (A / 256) pitch
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; Pass accumulator to set every (A / 256) pitch
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SetAffine
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SetAffine
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ldx #0
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ldx #0
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ldy #0
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ldy #0
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and #$00FF
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and #$00FF
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pha ; step size
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pha ; step size
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pea $0000
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pea $0000
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:loop lda 1,s
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:loop lda 1,s
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clc
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clc
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adc 3,s
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adc 3,s
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cmp #256
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cmp #256
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bcc :skip
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bcc :skip
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tya
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tya
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clc
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clc
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adc #256 ; Move to next BG1 line
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adc #256 ; Move to next BG1 line
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tay
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tay
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:skip and #$00FF ; always clamp to 256
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:skip and #$00FF ; always clamp to 256
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sta 1,s
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sta 1,s
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tya
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tya
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sta affine,x
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sta affine,x
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inx
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inx
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inx
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inx
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cpx #164
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cpx #164
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bcc :loop
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bcc :loop
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pla
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pla
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pla
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pla
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rts
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rts
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_ClearBG1Buffer
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_ClearBG1Buffer
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phb
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phb
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pha
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pha
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sep #$20
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sep #$20
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lda BG1DataBank
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lda BG1DataBank
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pha
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pha
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plb
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plb
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rep #$20
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rep #$20
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pla
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pla
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ldx #0
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ldx #0
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:loop
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:loop
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sta: $0000,x
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sta: $0000,x
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inc
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inc
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inx
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inx
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inx
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inx
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cpx #0
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cpx #0
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bne :loop
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bne :loop
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plb
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plb
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rts
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rts
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; Everytime either BG1 or BG0 Y-position changes, we have to update the Y-register
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; Everytime either BG1 or BG0 Y-position changes, we have to update the Y-register
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; value in all of the code fields (within the visible screen)
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; value in all of the code fields (within the visible screen)
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_ApplyBG1YPos
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_ApplyBG1YPos
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:virt_line equ tmp0
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:virt_line equ tmp0
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:lines_left equ tmp1
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:lines_left equ tmp1
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:draw_count equ tmp2
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:draw_count equ tmp2
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:ytbl_idx equ tmp3
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:ytbl_idx equ tmp3
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lda BG1StartY
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lda BG1StartY
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jsr Mod208
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jsr Mod208
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sta BG1StartYMod208
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sta BG1StartYMod208
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sta :ytbl_idx ; Start copying from the first entry in the table
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sta :ytbl_idx ; Start copying from the first entry in the table
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lda StartYMod208 ; This is the base line of the virtual screen
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lda StartYMod208 ; This is the base line of the virtual screen
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sta :virt_line ; Keep track of it
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sta :virt_line ; Keep track of it
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lda ScreenHeight
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lda ScreenHeight
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sta :lines_left
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sta :lines_left
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:loop
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:loop
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lda :virt_line
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lda :virt_line
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asl
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asl
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tax
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tax
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ldal BTableLow,x ; Get the address of the first code field line
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ldal BTableLow,x ; Get the address of the first code field line
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tay
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tay
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sep #$20
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sep #$20
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ldal BTableHigh,x
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ldal BTableHigh,x
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pha
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pha
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plb ; This is the bank that will receive the updates
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plb ; This is the bank that will receive the updates
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rep #$20
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rep #$20
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lda :virt_line
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lda :virt_line
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and #$000F
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and #$000F
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eor #$FFFF
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eor #$FFFF
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inc
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inc
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clc
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clc
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adc #16
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adc #16
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min :lines_left
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min :lines_left
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sta :draw_count ; Do this many lines
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sta :draw_count ; Do this many lines
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asl
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asl
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tax
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tax
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lda :ytbl_idx ; Read from this location in the BG1YTable
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lda :ytbl_idx ; Read from this location in the BG1YTable
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asl
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asl
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jsr CopyBG1YTableToBG1Addr
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jsr CopyBG1YTableToBG1Addr
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lda :virt_line ; advance to the virtual line after the segment we just
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lda :virt_line ; advance to the virtual line after the segment we just
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clc ; filled in
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clc ; filled in
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adc :draw_count
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adc :draw_count
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sta :virt_line
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sta :virt_line
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lda :ytbl_idx ; advance the index into the YTable
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lda :ytbl_idx ; advance the index into the YTable
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adc :draw_count
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adc :draw_count
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sta :ytbl_idx
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sta :ytbl_idx
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lda :lines_left ; subtract the number of lines we just completed
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lda :lines_left ; subtract the number of lines we just completed
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sec
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sec
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sbc :draw_count
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sbc :draw_count
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sta :lines_left
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sta :lines_left
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jne :loop
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jne :loop
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phk
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phk
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plb
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plb
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rts
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rts
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; Unrolled copy routine to move BG1YTable entries into BG1_ADDR position.
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; Unrolled copy routine to move BG1YTable entries into BG1_ADDR position.
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;
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;
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; A = intect into the BG1YTable array (x2)
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; A = index into the BG1YTable array (x2)
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; Y = starting line * $1000
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; Y = starting line * $1000
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; X = number of lines (x2)
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; X = number of lines (x2)
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CopyBG1YTableToBG1Addr
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CopyBG1YTableToBG1Addr
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jmp (:tbl,x)
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jmp (:tbl,x)
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:tbl da :none
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:tbl da :none
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da :do01,:do02,:do03,:do04
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da :do01,:do02,:do03,:do04
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da :do05,:do06,:do07,:do08
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da :do05,:do06,:do07,:do08
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da :do09,:do10,:do11,:do12
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da :do09,:do10,:do11,:do12
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da :do13,:do14,:do15,:do16
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da :do13,:do14,:do15,:do16
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:do15 tax
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:do15 tax
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bra :x15
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bra :x15
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:do14 tax
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:do14 tax
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bra :x14
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bra :x14
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:do13 tax
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:do13 tax
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bra :x13
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bra :x13
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:do12 tax
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:do12 tax
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bra :x12
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bra :x12
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:do11 tax
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:do11 tax
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bra :x11
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bra :x11
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:do10 tax
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:do10 tax
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bra :x10
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bra :x10
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:do09 tax
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:do09 tax
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bra :x09
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bra :x09
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:do08 tax
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:do08 tax
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bra :x08
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bra :x08
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:do07 tax
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:do07 tax
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bra :x07
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bra :x07
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:do06 tax
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:do06 tax
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bra :x06
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bra :x06
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:do05 tax
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:do05 tax
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bra :x05
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bra :x05
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:do04 tax
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:do04 tax
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bra :x04
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bra :x04
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:do03 tax
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:do03 tax
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bra :x03
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bra :x03
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:do02 tax
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:do02 tax
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bra :x02
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bra :x02
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:do01 tax
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:do01 tax
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bra :x01
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bra :x01
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:do16 tax
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:do16 tax
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ldal BG1YTable+30,x
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ldal BG1YTable+30,x
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sta BG1_ADDR+$F000,y
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sta BG1_ADDR+$F000,y
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:x15 ldal BG1YTable+28,x
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:x15 ldal BG1YTable+28,x
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sta BG1_ADDR+$E000,y
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sta BG1_ADDR+$E000,y
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:x14 ldal BG1YTable+26,x
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:x14 ldal BG1YTable+26,x
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sta BG1_ADDR+$D000,y
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sta BG1_ADDR+$D000,y
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:x13 ldal BG1YTable+24,x
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:x13 ldal BG1YTable+24,x
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sta BG1_ADDR+$C000,y
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sta BG1_ADDR+$C000,y
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:x12 ldal BG1YTable+22,x
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:x12 ldal BG1YTable+22,x
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sta BG1_ADDR+$B000,y
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sta BG1_ADDR+$B000,y
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:x11 ldal BG1YTable+20,x
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:x11 ldal BG1YTable+20,x
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sta BG1_ADDR+$A000,y
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sta BG1_ADDR+$A000,y
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:x10 ldal BG1YTable+18,x
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:x10 ldal BG1YTable+18,x
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sta BG1_ADDR+$9000,y
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sta BG1_ADDR+$9000,y
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:x09 ldal BG1YTable+16,x
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:x09 ldal BG1YTable+16,x
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sta BG1_ADDR+$8000,y
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sta BG1_ADDR+$8000,y
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:x08 ldal BG1YTable+14,x
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:x08 ldal BG1YTable+14,x
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sta BG1_ADDR+$7000,y
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sta BG1_ADDR+$7000,y
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:x07 ldal BG1YTable+12,x
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:x07 ldal BG1YTable+12,x
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sta BG1_ADDR+$6000,y
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sta BG1_ADDR+$6000,y
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:x06 ldal BG1YTable+10,x
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:x06 ldal BG1YTable+10,x
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sta BG1_ADDR+$5000,y
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sta BG1_ADDR+$5000,y
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:x05 ldal BG1YTable+08,x
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:x05 ldal BG1YTable+08,x
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sta: BG1_ADDR+$4000,y
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sta: BG1_ADDR+$4000,y
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:x04 ldal BG1YTable+06,x
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:x04 ldal BG1YTable+06,x
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sta BG1_ADDR+$3000,y
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sta BG1_ADDR+$3000,y
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:x03 ldal BG1YTable+04,x
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:x03 ldal BG1YTable+04,x
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sta BG1_ADDR+$2000,y
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sta BG1_ADDR+$2000,y
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:x02 ldal BG1YTable+02,x
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:x02 ldal BG1YTable+02,x
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sta BG1_ADDR+$1000,y
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sta BG1_ADDR+$1000,y
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:x01 ldal BG1YTable+00,x
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:x01 ldal BG1YTable+00,x
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sta: BG1_ADDR+$0000,y
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sta: BG1_ADDR+$0000,y
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:none rts
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:none rts
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; Unrolled copy routine to move BG1YTable entries into BG1_ADDR position with an additional
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; shift
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;
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; A = index into the BG1YTable array (x2)
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; Y = starting line * $1000
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; X = number of lines (x2)
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CopyBG1YTableToBG1Addr2
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jmp (:tbl,x)
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:tbl da :none
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da :do01,:do02,:do03,:do04
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da :do05,:do06,:do07,:do08
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da :do09,:do10,:do11,:do12
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da :do13,:do14,:do15,:do16
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:do15 tax
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bra :x15
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:do14 tax
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bra :x14
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:do13 tax
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bra :x13
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:do12 tax
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bra :x12
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:do11 tax
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bra :x11
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:do10 tax
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bra :x10
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:do09 tax
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bra :x09
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:do08 tax
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bra :x08
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:do16 tax
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ldal BG1YTable+30,x
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adcl BG1YOffsetTable+30,x
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sta BG1_ADDR+$F000,y
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:x15 ldal BG1YTable+28,x
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adcl BG1YOffsetTable+28,x
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sta BG1_ADDR+$E000,y
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||||||
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:x14 ldal BG1YTable+26,x
|
||||||
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adcl BG1YOffsetTable+26,x
|
||||||
|
sta BG1_ADDR+$D000,y
|
||||||
|
:x13 ldal BG1YTable+24,x
|
||||||
|
adcl BG1YOffsetTable+24,x
|
||||||
|
sta BG1_ADDR+$C000,y
|
||||||
|
:x12 ldal BG1YTable+22,x
|
||||||
|
adcl BG1YOffsetTable+22,x
|
||||||
|
sta BG1_ADDR+$B000,y
|
||||||
|
:x11 ldal BG1YTable+20,x
|
||||||
|
adcl BG1YOffsetTable+20,x
|
||||||
|
sta BG1_ADDR+$A000,y
|
||||||
|
:x10 ldal BG1YTable+18,x
|
||||||
|
adcl BG1YOffsetTable+18,x
|
||||||
|
sta BG1_ADDR+$9000,y
|
||||||
|
:x09 ldal BG1YTable+16,x
|
||||||
|
adcl BG1YOffsetTable+16,x
|
||||||
|
sta BG1_ADDR+$8000,y
|
||||||
|
:x08 ldal BG1YTable+14,x
|
||||||
|
adcl BG1YOffsetTable+14,x
|
||||||
|
sta BG1_ADDR+$7000,y
|
||||||
|
:x07 ldal BG1YTable+12,x
|
||||||
|
adcl BG1YOffsetTable+12,x
|
||||||
|
sta BG1_ADDR+$6000,y
|
||||||
|
:x06 ldal BG1YTable+10,x
|
||||||
|
adcl BG1YOffsetTable+10,x
|
||||||
|
sta BG1_ADDR+$5000,y
|
||||||
|
:x05 ldal BG1YTable+08,x
|
||||||
|
adcl BG1YOffsetTable+08,x
|
||||||
|
sta: BG1_ADDR+$4000,y
|
||||||
|
:x04 ldal BG1YTable+06,x
|
||||||
|
adcl BG1YOffsetTable+06,x
|
||||||
|
sta BG1_ADDR+$3000,y
|
||||||
|
:x03 ldal BG1YTable+04,x
|
||||||
|
adcl BG1YOffsetTable+04,x
|
||||||
|
sta BG1_ADDR+$2000,y
|
||||||
|
:x02 ldal BG1YTable+02,x
|
||||||
|
adcl BG1YOffsetTable+02,x
|
||||||
|
sta BG1_ADDR+$1000,y
|
||||||
|
:x01 ldal BG1YTable+00,x
|
||||||
|
adcl BG1YOffsetTable+00,x
|
||||||
|
sta: BG1_ADDR+$0000,y
|
||||||
|
:none rts
|
||||||
|
:do07 tax
|
||||||
|
bra :x07
|
||||||
|
:do06 tax
|
||||||
|
bra :x06
|
||||||
|
:do05 tax
|
||||||
|
bra :x05
|
||||||
|
:do04 tax
|
||||||
|
bra :x04
|
||||||
|
:do03 tax
|
||||||
|
bra :x03
|
||||||
|
:do02 tax
|
||||||
|
bra :x02
|
||||||
|
:do01 tax
|
||||||
|
bra :x01
|
||||||
|
|
||||||
|
|
||||||
|
|
||||||
|
|
||||||
|
|
||||||
|
|||||||
@ -238,5 +238,6 @@ BG1YTable lup 208
|
|||||||
]step = ]step+256
|
]step = ]step+256
|
||||||
--^
|
--^
|
||||||
|
|
||||||
|
BG1YOffsetTable ds 208*2*2
|
||||||
|
|
||||||
|
|
||||||
|
|||||||
Loading…
Reference in New Issue
Block a user