mirror of
https://github.com/sehugg/8bitworkshop.git
synced 2024-06-15 06:29:32 +00:00
88 lines
1.2 KiB
NASM
88 lines
1.2 KiB
NASM
.arch nano8
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.org 128
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.define PADDLE_X 0
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.define PADDLE_Y 1
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.define PLAYER_X 2
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.define PLAYER_Y 3
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.define ENEMY_X 4
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.define ENEMY_Y 5
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.define ENEMY_DIR 6
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.define SPEED 7
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.define TRACKPOS_LO 8
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.define TRACKPOS_HI 9
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.define IN_HPOS $40
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.define IN_VPOS $41
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.define IN_FLAGS $42
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.define F_DISPLAY 1
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.define F_HPADDLE 2
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.define F_VPADDLE 4
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.define F_HSYNC 8
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.define F_VSYNC 16
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.define F_COLLIDE 32
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Start:
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lda 128
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sta PLAYER_X
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sta ENEMY_X
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sta ENEMY_Y
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lda 180
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sta PLAYER_Y
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zero A
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sta SPEED
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; test hpaddle flag
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DisplayLoop:
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lda F_HPADDLE
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ldb IN_FLAGS
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andrb NOP
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bz DisplayLoop
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; [vpos] -> paddle_x
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ldb IN_VPOS
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movrb A
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sta PLAYER_X
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; wait for vsync=1 then vsync=0
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lda F_VSYNC
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ldb IN_FLAGS
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WaitForVsyncOn:
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andrb NOP
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bz WaitForVsyncOn
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WaitForVsyncOff:
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andrb NOP
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bnz WaitForVsyncOff
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; check collision
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lda F_COLLIDE
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ldb IN_FLAGS
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andrb NOP
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bz NoCollision
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; load slow speed
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lda 16
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sta SPEED
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NoCollision:
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; update speed
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ldb SPEED
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movrb A
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inc A
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; don't store if == 0
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bz MaxSpeed
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sta SPEED
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MaxSpeed:
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movrb A
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lsr A
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lsr A
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lsr A
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lsr A
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; add to lo byte of track pos
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ldb TRACKPOS_LO
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addrb B
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swapab
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sta TRACKPOS_LO
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swapab
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; update enemy vert pos
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ldb ENEMY_Y
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addrb A
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sta ENEMY_Y
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jmp DisplayLoop
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reset
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