home/movement.asm

2 files changed, 134 insertions, 4 deletions

diff --git a/home/movement.asm b/home/movement.asm
new file mode 100644
index 0000000..212a4b3
--- /dev/null
+++ b/home/movement.asm
@@ -0,0 +1,129 @@
+INCLUDE "constants.asm"
+
+SECTION "Movement ROM0", ROM0 [$19d1]
+
+InitMovementBuffer::
+	ld [wMovementBufferObject], a
+	xor a
+	ld [wMovementBufferCount], a
+	ld a, BANK(wMovementBuffer)
+	ld [wMovementBufferPointerBank], a
+	ld a, LOW(wMovementBuffer)
+	ld [wMovementBufferPointerAddr], a
+	ld a, HIGH(wMovementBuffer)
+	ld [wMovementBufferPointerAddr + 1], a
+	ret
+
+DecrementMovementBufferCount::
+	ld a, [wMovementBufferCount]
+	and a
+	ret z
+	dec a
+	ld [wMovementBufferCount], a
+	ret
+
+AppendToMovementBuffer:: ; 00:19f2
+	push hl
+	push de
+	ld hl, wMovementBufferCount
+	ld e, [hl]
+	inc [hl]
+	ld d, $0
+	ld hl, wMovementBuffer
+	add hl, de
+	ld [hl], a
+	pop de
+	pop hl
+	ret
+
+AppendToMovementBufferNTimes:: ; 00:1a03
+	push af
+	ld a, c
+	and a
+	jr nz, .asm_1a0a
+	pop af
+	ret
+
+.asm_1a0a: ; 00:1a0a
+	pop af
+.asm_1a0b: ; 00:1a0b
+	call AppendToMovementBuffer
+	dec c
+	jr nz, .asm_1a0b
+	ret
+
+ComputePathToWalkToPlayer::
+	push af
+	ld a, b
+	sub d
+	ld h, LEFT
+	jr nc, .asm_1a1d
+	dec a
+	cpl
+	ld h, RIGHT
+.asm_1a1d: ; 00:1a1d
+	ld d, a
+	ld a, c
+	sub e
+	ld l, UP
+	jr nc, .asm_1a28
+	dec a
+	cpl
+	ld l, DOWN
+.asm_1a28: ; 00:1a28
+	ld e, a
+	cp d
+	jr nc, .asm_1a32
+	ld a, h
+	ld h, l
+	ld l, a
+	ld a, d
+	ld d, e
+	ld e, a
+.asm_1a32: ; 00:1a32
+	pop af
+	ld b, a
+	ld a, h
+	call .GetMovementData
+	ld c, d
+	call AppendToMovementBufferNTimes
+	ld a, l
+	call .GetMovementData
+	ld c, e
+	call AppendToMovementBufferNTimes
+	ret
+
+.GetMovementData: ; 00:1a45
+	push de
+	push hl
+	ld l, b
+	ld h, $0
+	add hl, hl
+	add hl, hl
+	ld e, a
+	ld d, $0
+	add hl, de
+	ld de, .Data
+	add hl, de
+	ld a, [hl]
+	pop hl
+	pop de
+	ret
+
+.Data: ; 00:1a58
+	db $04, $05, $06, $07
+	db $08, $09, $0a, $0b
+	db $0c, $0d, $0e, $0f
+	
+; 	slow_step DOWN
+; 	slow_step UP
+; 	slow_step LEFT
+; 	slow_step RIGHT
+; 	step DOWN
+; 	step UP
+; 	step LEFT
+; 	step RIGHT
+; 	big_step DOWN
+; 	big_step UP
+; 	big_step LEFT
+; 	big_step RIGHT
diff --git a/wram.asm b/wram.asm
index 44aa1f2..a1f2fc0 100644
--- a/wram.asm
+++ b/wram.asm
@@ -314,10 +314,11 @@ wTitleSequenceOpeningType:: ; cc38
 wDebugWarpSelection:: ; cc39
     db
 
-    ds 6
-
-wcc40:: ; cc40
-    db
+wMovementBufferCount:: db ; cc3a
+wMovementBufferObject:: db ; cc3b
+	ptrba wMovementBufferPointer ; cc3c
+wMovementBuffer:: ; cc3f
+	ds 55
 
 SECTION "CC9C", WRAM0[$CC9C]