1 files changed, 57 insertions, 0 deletions
diff --git a/src/home/copy.asm b/src/home/copy.asm
new file mode 100644
index 0000000..8b21f90
--- /dev/null
+++ b/src/home/copy.asm
@@ -0,0 +1,57 @@
+; copy c bytes of data from hl to de, b times.
+; used to copy gfx data with c = TILE_SIZE
+CopyGfxData:
+	ld a, [wLCDC]
+	rla
+	jr nc, .next_tile
+.hblank_copy
+	push bc
+	push hl
+	push de
+	ld b, c
+	call JPHblankCopyDataHLtoDE
+	ld b, $0
+	pop hl
+	add hl, bc
+	ld e, l
+	ld d, h
+	pop hl
+	add hl, bc
+	pop bc
+	dec b
+	jr nz, .hblank_copy
+	ret
+.next_tile
+	push bc
+.copy_tile
+	ld a, [hli]
+	ld [de], a
+	inc de
+	dec c
+	jr nz, .copy_tile
+	pop bc
+	dec b
+	jr nz, .next_tile
+	ret
+
+; copy bc bytes from hl to de. preserves all registers except af
+CopyDataHLtoDE_SaveRegisters:
+	push hl
+	push de
+	push bc
+	call CopyDataHLtoDE
+	pop bc
+	pop de
+	pop hl
+	ret
+
+; copy bc bytes from hl to de
+CopyDataHLtoDE:
+	ld a, [hli]
+	ld [de], a
+	inc de
+	dec bc
+	ld a, c
+	or b
+	jr nz, CopyDataHLtoDE
+	ret