From 782a7c63a0e309ca49ed0dcfdfda8eaa6cb1c108 Mon Sep 17 00:00:00 2001
From: FeralChild64 <you@example.com>
Date: Wed, 18 Dec 2019 19:26:24 +0100
Subject: [PATCH] initial code for DolphinDOS detection (not working yet)

---
 c64/kernal/iec/talk.s                   |  9 +++++++
 c64/kernal/iec_fast/dolphindos_detect.s | 31 ++++++++++++++++++++++++-
 2 files changed, 39 insertions(+), 1 deletion(-)

diff --git a/c64/kernal/iec/talk.s b/c64/kernal/iec/talk.s
index d0c11e65..e65b4e68 100644
--- a/c64/kernal/iec/talk.s
+++ b/c64/kernal/iec/talk.s
@@ -41,9 +41,18 @@ common_talk_listen: // common part of TALK and LISTEN
 
 #endif // CONFIG_IEC_JIFFYDOS
 
+#if CONFIG_IEC_DOLPHINDOS
+
+	jsr iec_tx_command
+	jmp dolphindos_detect
+
+#else
 
 	jmp iec_tx_command
 
+#endif // no CONFIG_IEC_JIFFYDOS
+
+
 #else
 
 	jmp kernalerror_ILLEGAL_DEVICE_NUMBER
diff --git a/c64/kernal/iec_fast/dolphindos_detect.s b/c64/kernal/iec_fast/dolphindos_detect.s
index ef135e8d..093750bb 100644
--- a/c64/kernal/iec_fast/dolphindos_detect.s
+++ b/c64/kernal/iec_fast/dolphindos_detect.s
@@ -18,9 +18,38 @@
 #if CONFIG_IEC_DOLPHINDOS
 
 
-dolphindos_detect:
+dolphindos_detect: // XXX find out why this does not work
+
+	// According to logs collected from modified VICE emulator, original DolphinDOS ROM
+	// constantly reads $DD0D and $DD01 until handshake bit of $DD0D is set, or some kind
+	// of timeout occurs
+
+	php
+	ldx #$20
+
+dolphindos_detect_loop:
+
+	lda CIA2_ICR
+	and #$10
+	bne dolphindos_detect_success
+	lda CIA2_PRB                       // XXX do we need this read?
+
+	dex
+	bne dolphindos_detect_loop
+
+	// Protocol not detected
+
+	plp
+	rts
+
+dolphindos_detect_success:
+
+	// XXX protocol not implemented yet
 
 	panic #$00
 
+	plp
+	rts
+
 
 #endif // CONFIG_IEC_DOLPHINDOS