Other Link Movement Functions (WIP)

[vulcandth]

LinkMovementCheckRoomInBuffer::
; Input: hl: ring buffer to store in.
; Output: de: Pointer to Head, Sets Z flag if no room.
; clobbers hl, a
	dec hl
	ld a, [hld]
	ld e, a
	ld a, [hld]
	ld d, a

	ld a, [hld]
	ld h, [hl]
	ld l, a

	ld a, l
	sub e
	ld l, a
	ld a, h
	sbc d
	ld h, a

	ld a, l
	cp 1 ; Sets Z flag if no room.
	ret

LinkMovementStoreByte::
	; Input: a: Byte to store, hl: ring buffer to store in. 
	; Output: Z flag if no room.
	; clobbers hl, de, b
	ld b, a
	push hl
	call LinkMovementCheckRoomInBuffer
	pop hl
	ret z

	inc de
	push hl
	ld a, 16
	add l
	ld l, a
	adc h
	sub l
	cp d
	jr nz, .continue
	ld a, l
	cp e
	jr nz, .continue
	ld hl, -16
	add de, hl
.continue
	pop hl

	dec hl
	ld a, e
	ld [hld], a
	ld a, d
	ld [hl], a
	ld a, b
	ld [de], a
	ret

LinkMovementCheckBufferEmpty::
; Input: hl: ring buffer to store in.
; Output: hl: Pointer to Head, Sets Z flag if no room.
; clobbers hl, a
	dec hl
	ld a, [hld]
	ld e, a
	ld a, [hld]
	ld d, a

	ld a, [hld]
	ld h, [hl]
	ld l, a

	ld a, e
	sub l
	ld e, a
	ld a, d
	sbc h
	ld d, a

	ld a, e
	cp 1 ; Sets Z flag if no room.
	ret

LinkMovementGetByte::
	; Input: hl: ring buffer to get byte from
	; Output: a: byte from buffer, Z flag if buffer is empty
	; clobbers hl, de, b
	push hl
	call LinkMovementCheckBufferEmpty
	pop de
	ret z

	dec 
	
	; WIP

	ret