potsanity advancement

keydrop/dynamic_si_vram.asm

@@ -0,0 +1,181 @@
+
+StandItemGFXIDs = $7E07E0 ; 0x8 bytes for IDs
+StandingItemTransferGFX = $7E07E8 ; bit field for item transfers
+SICharRecID = $7E07E9 ; ID of receipt item for temp use
+SICharSource = $7E07EA ; source address of the sprite's graphics
+SIVRAMAddr = $7E07ED ; VRAM address to write the next slot to
+SIVRAMSlot = $7E07EF ; current vram slot to ask for
+SprSIChar = $7E07F0 ; standing item character for draw routine
+
+;===================================================================================================
+
+org somewhere ; todo
+
+SpriteDraw_DynamicStandingItem:
+	JSL Sprite_PrepOAMCoord_long ; 06E41C
+
+	LDA.b $00 : STA.b ($90),Y
+
+	LDA.b $01 : CMP.b #$01
+	LDA.b #$01 : ROL : STA.b ($92)
+
+	INY
+
+	REP #$21
+
+	LDA.b $02 : ADC.w #$0010
+	CMP.w #$0100
+
+	SEP #$20 : BCS .off_screen
+
+	SBC.b #$0F : STA.b ($90),Y
+
+	INY
+
+	LDA.w SprDropsItem,X : STA.b ($90),Y
+
+	INY
+
+	LDA.b $05 : STA.b ($90),Y
+
+.off_screen
+	JML SpriteDraw_Shadow_long ; 06DC5C
+
+; Call from standing/dropped items to request a free slot in VRAM in underworld
+; Enter with
+;   A = receipt ID
+;   X = sprite slot
+RequestStandingItemVRAMSlot:
+	JSR SetSISource
+	JSR GetSIVRAMSlot
+	RTL
+
+; Take 8-bit receipt ID and turn it into a 24-bit source graphics address
+; how we use this is TBD
+; we could set up a buffer of 8 24-bit addresses to reference during NMI
+; and we may or may not do decompression from here
+SetSISource:
+	STA.w SICharRecID
+	PHX ; make sure X is preserved during this
+
+	PLX
+	STA.w SICharSource+1
+	STY.w SICharSource+2 ; don't need to use Y, but just as an example
+
+	RTS
+
+GetSIVRAMSlot:
+	SEP #$30
+
+	PHX
+
+	LDA.w SIVRAMSlot : TAX
+
+	INC
+	CMP.b #$07 : BCC .fine
+
+	LDA.b #$00
+
+.fine
+	STA.w SIVRAMSlot
+
+	; flag this slot for a transfer
+	LDA.l .eightbits,X
+	ORA.l StandingItemTransferGFX
+	STA.l StandingItemTransferGFX
+
+	; set grapgics ID to look up for NMI transfer
+	LDA.w SICharRecID
+	STA.w StandItemGFXIDs,X
+
+	LDA.l .char,X
+	PLX
+
+	STA.w SprSIChar,X
+
+	RTS
+
+
+
+.char
+	db $20
+	db $22
+	db $2C
+	db $CB
+	db $E0
+	db $E5
+	db $EE
+
+.eightbits
+	db 1<<0
+	db 1<<1
+	db 1<<2
+	db 1<<3
+	db 1<<4
+	db 1<<5
+	db 1<<6
+	db 1<<7
+
+;===================================================================================================
+
+NMI_TransferSIGFX:
+	LDA.l StandingItemTransferGFX
+	BEQ .exit
+
+	REP #$20
+	AND.w #$00FF
+	STA.b $00
+
+	LDY.b #$80 : STY.w $2115
+
+	LDX.b #$00
+
+.next
+	LSR.b $00 : BEQ .done : BCC .skip
+
+	PHX
+
+	TXY
+	TXA : ASL : TAX
+
+	LDA.l .addr,X : STA.w $2116
+
+	; get source address based on ID
+	LDA.w StandItemGFXIDs,Y
+	; code
+	STA.b $04 ; source address
+	STY.w $4344 ; source bank
+
+	LDY.b #$10 ; DMA trigger
+
+	STA.w $4342 ; save address
+	LDA.w #$1801 : STA.w $4340 ; DMA type
+	LDA.w #64 : STA.w $4345 ; DMA size
+	STY.w $420B
+
+	STA.w $4345 ; DMA size again
+	CLC
+	LDA.b $04 : ADC.w #$0200 : STA.w $4344 ; assuming we've got things in squares in ROM
+	STY.w $420B
+
+	PLX
+
+.skip
+	INX
+	BRA .next
+
+
+.done
+	SEP #$20
+
+.exit
+	RTL
+
+.addr
+	dw $8800>>1
+	dw $8840>>1
+	dw $8980>>1
+	dw $9960>>1
+	dw $9C00>>1
+	dw $9CA0>>1
+	dw $9DC0>>1