Official Hex/ASM/Etc. Help Thread

;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
;
; Homing Pipe Cannon
;	by MarioFanGamer
;
; This sprite is a recreation of a barrel cannon from
; Donkey Kong Country 3 which will follow the player
; once entered until the latter lands on the ground.
; It is blocked by walls which allows you to limit its
; movement.
; Do note that you still can shoot fireballs and use the
; cape you implement patches which disable them under
; certain situations.
;
; Using extra bytes: No
;
; Extra property byte 1: Vertical speed of the player
;	when getting shot.
;
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;

; If using the disable fireball flag patch,
; set that one to the freeRAM set in the patch
!DisableFireballs = 0

!ShootSound = $09			; The sound to play when you get shot
!ShootBank = $1DFC|!addr	;

!PrepareShootTime = $10		; The time the cannon awaits in the prepare state

; Graphics
Tiles:
db $80,$85,$87,$89

XOffsets:
db $00,$10,$00,$10

YOffsets:
db $00,$00,$10,$10

; Internal defines

; The state of the cannon
!CannonState = !C2
; 0: Stationary but ready
; 1: Prepare to shoot
; 2: Following the player

; How long must the cannon wait until it can catch the player?
!TimerDisable = !1540

; This is simply used to run the desired interaction points
; The sprite itself doesn't apply any kind of movement on its own.
DummySpeed:
db $10,$F0

print "MAIN ",pc
	PHB
	PHK
	PLB
	JSR Main
	PLB
RTL

Main:
	JSR Graphics			; Graphics
	
	LDA !14C8,x				; Default stuff.
	EOR #$08				;
	ORA $9D					;
	BNE .Return				;
							;
	%SubOffScreen()			; A is already zero.
							;
	LDA !CannonState,x		; Get current cannon state.
	DEC						;
	BEQ .PrepareShoot		; If Mario is in cannon...
	DEC						;
	BNE .NotMoving			; If cannon isn't moving...
							;
	LDA $72					; Stop cannon if player is on ground.
	BNE .InAir				;
	STZ !CannonState,x		;
.InAir:						;
							;
	; LDA !B6,x				;
	; BPL .NormalPos			;
	; LDA !E4,x				;
	; PHA						;
	; SEC : SBC #$01			;
	; STA !E4,x				;
	; LDA !14E0,x				;
	; PHA						;
	; SBC #$00				;
	; STA !14E0,x				;
; .NormalPos:					;
							;
	JSL $019138|!bank		; Run block interaction.
							;
	LDY #$00				; SubHorzPos with offset.
	LDA !14E0,x				;
	XBA						;
	LDA !E4,x				;
	REP #$20				;
	CLC : ADC #$0010		; Centre of sprite
	STA $00					;
	LDA $94					;
	CLC : ADC #$0008		; Centre of Mario
	CMP $00					;
	SEP #$20				;
	BCS .RightOfCannon		;
	INY						;
.RightOfCannon:				;
							;
	LDA DummySpeed,y		; Set speed so interaction points run.
	STA !B6,x				; (Speed doesn't get actually applied, btw.)
							;
	LDA !1588,x				; Is the cannon blocked in a direction?
	AND #$03				;
	BNE .NotMoving			; If so, don't move it.
							;
	LDA $94					;
	SEC : SBC #$08			; Mario's position offset
	STA !E4,x				;
	LDA $95					;
	SBC #$00				;
	STA !14E0,x				;
							;
.NotMoving:					;
	LDA !TimerDisable,x		;
	BNE .NoInteraction		;
	JSL $01A7DC|!bank		;
	BCC .NoInteraction		;
	LDA #$01				; Set state
	STA !CannonState,x		;
	LDA #!PrepareShootTime	; Timer until cannon shoots
	STA !TimerDisable,x		;
	JSR SpawnContactGraphics; Like in DKC3!
.NoInteraction:				;
.Return:					;
RTS							;
							;
.PrepareShoot:				;
	LDA #$FF				; Hide player (and Yoshi even not riding...)
	STA $78					;
							;
	LDA !D8,x				; Put player in cannon
	SEC : SBC #$0B			;
	STA $96					;
	LDA !14D4,x				;
	SBC #$00				;
	STA $97					;
	LDA !E4,x				;
	CLC : ADC #$08			;
	STA $94					;
	LDA !14E0,x				;
	ADC #$00				;
	STA $95					;
							;
	STZ $7B					; Remove speed of player.
	STZ $7D					;
							;
if !DisableFireballs		;
	LDA #$01				; Disable fireball shooting if possible.
	STA !DisableFireballs	;
endif						;
							;
	LDA !TimerDisable,x		; Ready to shoot?
	BNE .Return2			;
							;
	LDA #$10				; Prevent cannon from catching the player
	STA !TimerDisable,x		; right after shooting
							;
	LDA !extra_prop_1,x		; Give it some speed!
	STA $7D					;
	INC !CannonState,x		; Set cannon to moving.
							;
	LDA #!ShootSound		; Cannon shot sound
	STA !ShootBank			;
							;
if !DisableFireballs		;
	STZ !DisableFireballs	; Enable shooting fireballs
endif						;
							;
	LDA #$0B				; Set Mario to jumping frame.
	STA $72					;
							;
	LDA #$08				; Spawn some appropriate smoke.
	STA $00					;
	LDA #$F8				;
	STA $01					;
	LDA #$1B				;
	STA $02					;
	LDA #$01				;
	%SpawnSmoke()			;
.Return2:					;
RTS							;


;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
; Simple 32x32 GFX routine
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;


Graphics:					;
	%GetDrawInfo()			;
							;
	LDA !15F6,x				; Get sprite properties with level mode priority.
	ORA $64					;
	STA $02					;
							;
	LDX #$03				;
.Loop						;
	LDA $00					; Code is really self-explanatory
	CLC : ADC XOffsets,x	; Especially since the graphics are static
	STA $0300|!addr,y		;
	LDA $01					;
	CLC : ADC YOffsets,x	;
	STA $0301|!addr,y		;
	LDA Tiles,x				;
	STA $0302|!addr,y		;
	LDA $02					;
	STA $0303|!addr,y		;
	INY #4					;
	DEX						;
	BPL .Loop				;
							;
	LDX $15E9|!addr			; Restore sprite index
	LDY #$02				; 16x16 tiles
	LDA #$03				; Four objects
	%FinishOAMWrite()		;
RTS							;


;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
; Spawn contact graphics
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;


SpawnContactGraphics:		;
	LDY #$03				; Loop through every smoke slot
.Loop						;
	LDA $17C0|!addr,y		;
	BEQ .EmptySlot			;
	DEY						;
	BPL .Loop				;
RTS							;
							;
.EmptySlot:					;
	LDA #$02				; Set type (contact graphics)
	STA $17C0|!addr,y		;
	LDA $D3					; Offset graphics
	CLC : ADC #$10			;
	STA $17C4|!addr,y		;
	LDA $D1					;
	STA $17C8|!addr,y		;
	LDA #$08				; Set duration
	STA $17CC|!addr,y		;
RTS							;