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111 lines
1.7 KiB
ArmAsm
111 lines
1.7 KiB
ArmAsm
; Square Wave Pattern
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; by Vince `deater` Weaver
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; zero page locations
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HGR_SHAPE = $1A
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HGR_SHAPE2 = $1B
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HGR_BITS = $1C
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GBASL = $26
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GBASH = $27
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A5H = $45
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XREG = $46
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YREG = $47
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; C0-CF should be clear
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; D0-DF?? D0-D5 = HGR scratch?
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HGR_DX = $D0 ; HGLIN
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HGR_DX2 = $D1 ; HGLIN
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HGR_DY = $D2 ; HGLIN
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HGR_QUADRANT = $D3
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HGR_E = $D4
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HGR_E2 = $D5
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HGR_X = $E0
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HGR_X2 = $E1
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HGR_Y = $E2
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HGR_COLOR = $E4
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HGR_HORIZ = $E5
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HGR_SCALE = $E7
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HGR_SHAPE_TABLE = $E8
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HGR_SHAPE_TABLE2= $E9
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HGR_COLLISIONS = $EA
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HGR_ROTATION = $F9
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FRAME = $FC
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FRAMEH = $FD
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XPOS = $FE
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YPOS = $FF
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; ROM calls
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HGR2 = $F3D8
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HGR = $F3E2
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HPOSN = $F411
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DRAW0 = $F601
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XDRAW0 = $F65D
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XDRAW1 = $F661
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RESTORE = $FF3F
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.zeropage
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.globalzp rot_smc
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square_wave:
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; $E7
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.byte $0A ; harmless ASL but also size of HGR_SCALE
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; as we load this at $E7
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; lda #10
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; sta HGR_SCALE
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; $E8,$E9,$EA (HGR_COLLISIONS=$F3)
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jsr HGR2 ; Hi-res, full screen ; 3
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; Y=0, A=0 after this call
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; A and Y are 0 here.
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; X is left behind by the boot process?
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; tya
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; tax ; load X with 0
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; ldy #0
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; ldx #00
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; lda #00
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jsr HPOSN ; set screen position to X= (y,x) Y=(a)
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; saves X,Y,A to zero page
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; after Y= orig X/7
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; A and X are ??
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pattern_loop:
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ldx #<pattern_table ; point to bottom byte of shape address
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ldy #>pattern_table ; point to top byte of shape address
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; ROT in A
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; this will be 0 2nd time through loop, arbitrary otherwise
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rot_smc:
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lda #1 ; rotation (ROT=)
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jsr XDRAW0 ; XDRAW 1 AT X,Y
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; Both A and X are 0 at exit
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; Z flag set on exit
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; Y varies
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inc HGR_BITS
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; lda HGR_COLLISIONS
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bne pattern_loop
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inc rot_smc+1
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jsr $F3F6 ; clear screen to HGR_BITS
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jmp pattern_loop
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pattern_table:
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.byte 37,53,0
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