From 69e9fcc59363e3be82d4783bf5fc46daf40bfa15 Mon Sep 17 00:00:00 2001
From: Astrid Smith
Date: Sat, 26 Jun 2010 21:33:19 -0700
Subject: Added bank-swapping routines (incomplete: doesn't implement memory
 map mode 1)

---
 bankswap.c | 27 +++++++++++++++++++++++++++
 ports.asm  | 19 ++++++++++++++++++-
 2 files changed, 45 insertions(+), 1 deletion(-)
 create mode 100644 bankswap.c

diff --git a/bankswap.c b/bankswap.c
new file mode 100644
index 0000000..db4931c
--- /dev/null
+++ b/bankswap.c
@@ -0,0 +1,27 @@
+/* Memory bank swapping driver for 680 project.
+ *
+ * Copyright 2010, Astrid Smith
+ * GPL
+ */
+
+#include "asm_vars.h"
+
+void* pages[256];
+
+/* Address 0000 is always bound to ROM page 0. */
+
+/* Process orders to swap bank A (port 06, 0x4000). */
+void bankswap_4000_write(char data)
+{
+	mem_page_1 = pages[data];
+	mem_page_loc_1 = data;
+	return;
+}
+
+/* Process orders to swap bank B (port 07, 0x8000). */
+void bankswap_b_write(char data)
+{
+	mem_page_2 = pages[data];
+	mem_page_loc_2 = data;
+	return;
+}
diff --git a/ports.asm b/ports.asm
index b2587aa..815a69c 100644
--- a/ports.asm
+++ b/ports.asm
@@ -539,10 +539,24 @@ port_in_03:
 port_out_03:
 port_in_04:
 port_out_04:
+	;; Bank B paging
+	;; XXX save registers
+	move.b	d1,-(a7)
+	jsr	bankswap_b_write
+	addq	2,a7
+	rts
+
 port_in_05:
 port_out_05:
 port_in_06:
 port_out_06:
+	;; Bank A paging
+	;; XXX save registers
+	move.b	d1,-(a7)
+	jsr	bankswap_a_write
+	addq	2,a7
+	rts
+
 port_in_07:
 port_out_07:
 port_in_08:
@@ -663,6 +677,7 @@ port_out_10_set_row:
 
 port_in_11:
 	;; LCD data
+	;; XXX save registers
 	jsr	video_read
 	move.b	d0,d1		; return value
 	rts
@@ -670,7 +685,9 @@ port_in_11:
 port_out_11:
 	;; LCD data
 	move.b	d1,-(a7)
-	bra	video_write
+	;; XXX save registers
+	jsr	video_write
+	rts
 
 port_in_12:
 port_out_12:
-- 
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