joypad in its own file + optionally skip intro by compiling with DIRECT_TO_GAME

Code/joypad.asm

@@ -0,0 +1,69 @@
+INCLUDE "hardware.inc"
+
+Section "Joypad memory", HRAM
+; Bits 0..7 are A, B, Select, Start, Right, Left, Up, Down
+JoypadPressed: ds 1
+JoypadWasPressed: ds 1
+JoypadDown: ds 1
+
+EXPORT ReadJoypad
+SECTION "Read Joypad", ROM0
+ReadJoypad:
+	; read directions
+	ld a, P1F_5
+	ldh [rP1], a 
+	ldh a, [rP1]
+	ldh a, [rP1]
+	ldh a, [rP1]
+	ldh a, [rP1]
+	and a, $0F
+	swap a ; move into high nibble
+	ld b, a
+	
+	; read buttons
+	ld a, P1F_4
+	ldh [rP1], a 
+	ldh a, [rP1]
+	ldh a, [rP1]
+	ldh a, [rP1]
+	ldh a, [rP1]
+	and a, $0F
+
+	; merge directions and buttons
+	; complement so that active buttons read as 1
+	or a, b
+	cpl
+
+	; store currently pressed buttons
+	ldh [JoypadPressed], a
+
+	; reset joypad
+	ld a, $30
+	ldh [rP1], a
+
+	ret
+
+SECTION "Update joypad", ROM0
+UpdateJoypad:	
+	; compute & store just pressed buttons
+	ldh a, [JoypadPressed]
+	ld b, a
+	ldh a, [JoypadWasPressed]
+	cpl 
+	and a, b
+	ldh [JoypadDown], a
+	
+	; update was pressed
+	ld a, b
+	ldh [JoypadWasPressed], a
+	
+	ret
+
+EXPORT InitJoypad
+SECTION "Init joypad", ROM0
+InitJoypad:
+	xor a
+	ldh [JoypadDown], a
+	ldh [JoypadPressed], a
+	ldh [JoypadWasPressed], a
+	ret