From 8dc3c22d3d0a2f34cd6321365761df66e32847f3 Mon Sep 17 00:00:00 2001
From: Mike Pavone <pavone@retrodev.com>
Date: Sun, 30 Dec 2012 22:39:41 -0800
Subject: Implemented HV counter

---
 runtime.S | 13 +++++++++++++
 1 file changed, 13 insertions(+)

(limited to 'runtime.S')

diff --git a/runtime.S b/runtime.S
index 5debd57..a383130 100644
--- a/runtime.S
+++ b/runtime.S
@@ -369,6 +369,8 @@ m68k_read_byte_scratch1:
 	jbe cart_b
 	cmp $0xE00000, %ecx
 	jae workram_b
+	cmp $0xC00000, %ecx
+	jae vdp_psg_b
 	cmp $0xA10000, %ecx
 	jb not_io_b
 	cmp $0xA12000, %ecx
@@ -378,6 +380,17 @@ not_io_b:
 	xor %cl, %cl
 	dec %cl
 	ret
+vdp_psg_b:
+	test $0x2700E0, %ecx
+	jnz crash
+	and $0x1F, %ecx
+	bt $0, %ecx
+	jnc vdp_swap
+	jmp do_vdp_port_read
+vdp_swap:
+	call do_vdp_port_read
+	shr $8, %cx
+	ret
 workram_b:
 	/* deal with byte swapping */
 	xor $1, %ecx
-- 
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