;; #LAYOUT# M65 KERNAL_1 #TAKE
;; #LAYOUT# *   *        #IGNORE

; Helper routines for DMAgic usage

; See:
; - https://c65gs.blogspot.com/2019/03/auto-detecting-required-revision-of.html
; - https://c65gs.blogspot.com/2018/01/improving-dmagic-controller-interface.html


m65_dmagic_oper_fill:

	; To configure job parameters, use:
	; - M65_DMAJOB_SIZE_*
	; - M65_DMAJOB_DST_*
	; - .A - byte for filling
	; Afterwards, consider M65_DMAJOB_DST_2 and M65_DMAJOB_*_3 destroyed.

	; Set fill address
	
	sta M65_DMAJOB_SRC_0

	; Set operation type

	lda #$03                           ; operation: FILL
	sta M65_DMAGIC_LIST+6

	; Put this into M65_DMAJOB_SRC_2 too - to make sure flags (4 most significant bits) are cleared

	sta M65_DMAJOB_SRC_2

	; Adapt the addresses, launch the job

	jsr m65_dmagic_adapt_dst
	bra m65_dmagic_launch

m65_dmagic_oper_copy:

	; To configure job parameters, use:
	; - M65_DMAJOB_SIZE_*
	; - M65_DMAJOB_SRC_*
	; - M65_DMAJOB_DST_*
	; Afterwards, consider M65_DMAJOB_*_2 and M65_DMAJOB_*_3 destroyed.

	; Set operation type

	lda #$00                           ; operation: COPY
	sta M65_DMAGIC_LIST+6

	; Adapt the addresses, launch the job

	jsr m65_dmagic_adapt_src
	jsr m65_dmagic_adapt_dst

	; XXX possibly prepare separate version for the opposite direction  - change direction
	;     by setting bit 6 of M65_DMAJOB_*_2

	; FALLTROUGH

m65_dmagic_launch:

	; Launch the DMA list

	lda #$00
	sta DMA_ADDRBANK                   ; $D702
	sta DMA_ADDRMB                     ; $D704

	lda #>M65_DMAGIC_LIST
	sta DMA_ADDRMSB                    ; $D701
	lda #<M65_DMAGIC_LIST
	sta DMA_ETRIG                      ; $D705

	rts


m65_dmagic_adapt_src:

	; We need to adapt the addresses:
	; - M65_DMAJOB_SRC_2 - contain bits 16-23, should contain 16-19
	; - M65_DMAJOB_SRC_3 - contain bits 24-27, should contain 20-27

	lda M65_DMAJOB_SRC_2
	pha

	asl
	rol M65_DMAJOB_SRC_3 
	asl
	rol M65_DMAJOB_SRC_3
	asl
	rol M65_DMAJOB_SRC_3
	asl
	rol M65_DMAJOB_SRC_3

	pla
	and #%00001111
	sta M65_DMAJOB_SRC_2

	rts


m65_dmagic_adapt_dst:

	; We need to adapt the addresses:
	; - M65_DMAJOB_DST_2 - contain bits 16-23, should contain 16-19
	; - M65_DMAJOB_DST_3 - contain bits 24-27, should contain 20-27

	lda M65_DMAJOB_DST_2
	pha

	asl
	rol M65_DMAJOB_DST_3 
	asl
	rol M65_DMAJOB_DST_3
	asl
	rol M65_DMAJOB_DST_3
	asl
	rol M65_DMAJOB_DST_3

	pla
	and #%00001111
	sta M65_DMAJOB_DST_2

	rts


m65_dmagic_init:

	; Set common job parameters

	lda #$0A
	sta M65_DMAGIC_LIST+0              ; <- $0A = use F018A list format (it is shorter by 1 byte)
	lda #$80
	sta M65_DMAGIC_LIST+1              ; <- $80 = next byte is highest 8 bits of source address
	inc
	sta M65_DMAGIC_LIST+3              ; <- $81 = next byte is highest 8 bits of destination address

	lda #$00
	sta M65_DMAGIC_LIST+5              ; <- end of options

	; Modulo is never used - thus our list is 15 bytes, not 17

	rts