190 lines
2.9 KiB
ArmAsm
190 lines
2.9 KiB
ArmAsm
; Rotating Gears
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; by Vince `deater` Weaver
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; 138 bytes -- original for Apple II bot
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; 134 bytes -- only set SCALE once
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; 131 bytes -- unecessary var set, change jmp to bra
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; 110 bytes -- move draw_scene to a function
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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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ROTATION = $FA
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SMALLER = $FB
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CURRENT_ROT = $FF
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; Soft Switches
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PAGE1 = $C054 ; Page1
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PAGE2 = $C055 ; Page2
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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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WAIT = $FCA8 ;; delay 1/2(26+27A+5A^2) us
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RESTORE = $FF3F
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gears:
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;============================
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; scene 1
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;============================
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jsr HGR ; Hi-res, full screen ; 3
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; Y=0, A=0 after this call
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lda #8
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sta HGR_SCALE
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lda #1
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sta CURRENT_ROT
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sty SMALLER ; init to 0
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jsr draw_scene
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;===================
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; scene2
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;===================
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jsr HGR2 ; set to hires PAGE2, full screen
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; Y=0, A=0 after
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lda #<gear2_table ; draw alternate gear
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sta which_smc+1
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jsr draw_scene
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;===================
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; rotate forever
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;===================
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; just page flipping with a delay
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rotate_it:
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bit PAGE1
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lda #255
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jsr WAIT
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bit PAGE2
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lda #255
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jsr WAIT
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beq rotate_it ; bra
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;=========================
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; draw scene
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;=========================
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; Y must be 0 at entry
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draw_scene:
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; Y is zero from HGR
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ldx #110
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lda #10
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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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ldy #32
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jsr draw_gear
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ldy #0
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ldx #235
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lda #100
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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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inc SMALLER
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ldy #16
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jsr draw_gear
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dec SMALLER
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rts
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;===============================
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;===============================
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;===============================
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;===============================
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draw_gear:
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sty ROTATION
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gear1_loop:
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inc CURRENT_ROT
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inc CURRENT_ROT
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; inc rot_smc+1
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; inc rot_smc+1
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lda SMALLER
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beq not_smaller
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inc CURRENT_ROT
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inc CURRENT_ROT
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; inc rot_smc+1
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; inc rot_smc+1
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not_smaller:
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which_smc:
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ldx #<gear1_table ; point to bottom byte of shape address
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ldy #>gear1_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 ; ROT=0
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lda CURRENT_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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dec ROTATION
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bne gear1_loop
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rts
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gear1_table:
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.byte $25,$35,$00 ; 37,53,0
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gear2_table:
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.byte $2c,$2e,$00 ; 44,46,0
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