rename common/ to home/

1 files changed, 31 insertions, 0 deletions

diff --git a/home/double_speed.asm b/home/double_speed.asm
new file mode 100644
index 000000000..fc1234215
--- /dev/null
+++ b/home/double_speed.asm
@@ -0,0 +1,31 @@
+; The CGB hardware introduces Double Speed Mode.
+; While active, the clock speed is doubled.
+
+; The hardware can switch between normal speed
+; and double speed at any time, but LCD output
+; collapses during the switch.
+
+DoubleSpeed: ; 2fef
+	ld hl, rKEY1
+	bit 7, [hl]
+	jr z, SwitchSpeed
+	ret
+; 2ff7
+
+NormalSpeed: ; 2ff7
+	ld hl, rKEY1
+	bit 7, [hl]
+	ret z
+; 2ffd
+
+SwitchSpeed: ; 2ffd
+	set 0, [hl]
+	xor a
+	ld [rIF], a
+	ld [rIE], a
+	ld a, $30
+	ld [rJOYP], a
+	stop ; rgbasm adds a nop after this instruction by default
+	ret
+; 300b
+