97 lines
1.1 KiB
ArmAsm
97 lines
1.1 KiB
ArmAsm
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; Handle alien laser
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; uses laser1 slot
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; should handle multiple at once?
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;laser1_out: .byte $0
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;laser1_start: .byte $0
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;laser1_end: .byte $0
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;laser1_y: .byte $0
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;laser1_direction: .byte $0
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;laser1_count: .byte $0
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;=========================
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; fire alien laser
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;=========================
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; which alien in X
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fire_alien_laser:
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lda laser1_out
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bne done_fire_alien_laser
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lda alien_x,X
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sta COLLISION_X
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lda alien_y,X
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sta COLLISION_Y
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; activate laser slot
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inc laser1_out
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; reset count
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lda #0
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sta laser1_count
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; set y
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; assume for now no crouching
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lda alien_y,X
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clc
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adc #4
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sta laser1_y
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; set direction
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lda alien_direction,X
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sta laser1_direction
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beq alien_laser_left
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bne alien_laser_right
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; set x
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alien_laser_left:
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stx LASER_TEMP
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jsr calc_gun_left_collision
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ldx LASER_TEMP
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lda alien_x,X
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sec
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sbc #2
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sta laser1_end
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sec
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sbc #10
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sta laser1_start
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jmp done_fire_alien_laser
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alien_laser_right:
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stx LASER_TEMP
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jsr calc_gun_right_collision
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ldx LASER_TEMP
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lda alien_x,X
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clc
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adc #5
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sta laser1_start
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clc
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adc #10
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sta laser1_end
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done_fire_alien_laser:
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rts
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