1 files changed, 56 insertions, 0 deletions
diff --git a/source/bank_00.asm b/source/bank_00.asm
new file mode 100644
index 0000000..ac58661
--- /dev/null
+++ b/source/bank_00.asm
@@ -0,0 +1,56 @@
+INCLUDE "hardware.inc"
+
+SECTION "vram_copy", ROM0[$0fbd]
+
+; Parameters:
+; a - bank
+; hl - source
+; de - dest
+; bc - length
+vram_copy::
+    ld [w_bank_temp], a
+    ld a, [w_bank_rom]
+    push af
+    ld a, [w_bank_temp]
+    ld [w_bank_rom], a
+    ld [rROMB0], a
+
+.loop
+    ldh a, [rLCDC]
+    bit 7, a
+    jr z, .in_vblank
+
+.wait_vblank
+    ldh a, [rSTAT]
+    and $03
+    jr z, .wait_vblank
+
+.in_vblank
+    ldh a, [rSTAT]
+    and $03
+    jr nz, .in_vblank
+
+    ld a, [hl+]
+    ld [de], a
+    inc de
+    ld a, [hl+]
+    ld [de], a
+    inc de
+    ld a, [hl+]
+    ld [de], a
+    inc de
+    ld a, [hl+]
+    ld [de], a
+    inc de
+    dec bc
+    dec bc
+    dec bc
+    dec bc
+    ld a, b
+    or c
+    jr nz, .loop
+
+    pop af
+    ld [w_bank_rom], a
+    ld [rROMB0], a
+    ret