split serial handshake into common/handshake.asm

1 files changed, 38 insertions, 0 deletions

diff --git a/common/handshake.asm b/common/handshake.asm
new file mode 100644
index 000000000..8ed1473e4
--- /dev/null
+++ b/common/handshake.asm
@@ -0,0 +1,38 @@
+AskSerial: ; 2063
+; send out a handshake while serial int is off
+	ld a, [$c2d4]
+	bit 0, a
+	ret z
+	
+	ld a, [$c2d5]
+	and a
+	ret nz
+	
+; once every 6 frames
+	ld hl, $ca8a
+	inc [hl]
+	ld a, [hl]
+	cp 6
+	ret c
+	
+	xor a
+	ld [hl], a
+	
+	ld a, $c
+	ld [$c2d5], a
+	
+; handshake
+	ld a, $88
+	ld [rSB], a
+	
+; switch to internal clock
+	ld a, %00000001
+	ld [rSC], a
+	
+; start transfer
+	ld a, %10000001
+	ld [rSC], a
+	
+	ret
+; 208a
+