home: disassemble vblank and associated functions

Signed-off-by: Tauwasser <Tauwasser@tauwasser.eu>

1 files changed, 51 insertions, 0 deletions

diff --git a/home/joypad.asm b/home/joypad.asm
new file mode 100644
index 0000000..80371b7
--- /dev/null
+++ b/home/joypad.asm
@@ -0,0 +1,51 @@
+INCLUDE "constants.asm"
+
+SECTION "Joypad functions", ROM0[$07FE]
+
+Joypad:: ; 7fe (0:7fe)
+	ld a, [$d4ab]
+	and $d0
+	ret nz
+	ld a, 1 << 5 ; select direction keys
+	ldh [rJOYP], a
+	ldh a, [rJOYP]
+	ldh a, [rJOYP]
+	cpl
+	and $0f
+	swap a
+	ld b, a
+	ld a, 1 << 4 ; select button keys
+	ldh [rJOYP], a
+	ldh a, [rJOYP]
+	ldh a, [rJOYP]
+	ldh a, [rJOYP]
+	ldh a, [rJOYP]
+	ldh a, [rJOYP]
+	ldh a, [rJOYP]
+	cpl
+	and $0f
+	or b
+	ld b, a
+	ld a, (1 << 5 | 1 << 4) ; port reset
+	ldh [rJOYP], a
+	ldh a, [hJoypadDown]
+	ld e, a
+	xor b
+	ld d, a
+	and e
+	ldh [hJoypadReleased], a
+	ld a, d
+	and b
+	ldh [hJoypadPressed], a
+	ld c, a
+	ldh a, [hJoypadSum]
+	or c
+	ldh [hJoypadSum], a
+	ld a, b
+	ldh [hJoypadDown], a
+	ldh [hJoypadDown2], a
+	and $0f
+	cp $0f
+	jp z, Reset
+	ret
+; 0x84a
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