1 files changed, 36 insertions, 0 deletions
diff --git a/home/oam.asm b/home/oam.asm
new file mode 100644
index 00000000..8a940d97
--- /dev/null
+++ b/home/oam.asm
@@ -0,0 +1,36 @@
+; INPUT:
+; a = oam block index (each block is 4 oam entries)
+; b = Y coordinate of upper left corner of sprite
+; c = X coordinate of upper left corner of sprite
+; de = base address of 4 tile number and attribute pairs
+WriteOAMBlock::
+	ld h, HIGH(wOAMBuffer)
+	swap a ; multiply by 16
+	ld l, a
+	call .writeOneEntry ; upper left
+	push bc
+	ld a, 8
+	add c
+	ld c, a
+	call .writeOneEntry ; upper right
+	pop bc
+	ld a, 8
+	add b
+	ld b, a
+	call .writeOneEntry ; lower left
+	ld a, 8
+	add c
+	ld c, a
+	                      ; lower right
+.writeOneEntry
+	ld [hl], b ; Y coordinate
+	inc hl
+	ld [hl], c ; X coordinate
+	inc hl
+	ld a, [de] ; tile number
+	inc de
+	ld [hli], a
+	ld a, [de] ; attribute
+	inc de
+	ld [hli], a
+	ret