From 80858801300a2f48ad250721a79ebc7b1b0aba92 Mon Sep 17 00:00:00 2001
From: Nebuleon Fumika
Date: Thu, 20 Dec 2012 18:10:38 -0500
Subject: Remove the SNES Open Bus behaviour by default. Also simplify
 translation again.

SNES Open Bus is a quirk of the memory subsystem that allow reads of invalid addresses to return the last byte read from memory. However, it is seldom needed by a game, and it costs 1 to 3 MIPS instructions per SNES instruction to emulate.

If you need SNES Open Bus, you can remove -DNO_OPEN_BUS from the Makefile.
---
 source/sa1.cpp | 9 +++++++++
 1 file changed, 9 insertions(+)

(limited to 'source/sa1.cpp')

diff --git a/source/sa1.cpp b/source/sa1.cpp
index 39b08bb..eb10d33 100644
--- a/source/sa1.cpp
+++ b/source/sa1.cpp
@@ -228,14 +228,23 @@ uint8 S9xSA1GetByte (uint32 address)
 #ifdef DEBUGGER
 //	printf ("R(B) %06x\n", address);
 #endif
+#ifndef NO_OPEN_BUS
         return OpenBus;
+#else
+		return 0; // Arbitrarily chosen value [Neb]
+#endif
     }
 }
 
 uint16 S9xSA1GetWord (uint32 address)
 {
+#ifndef NO_OPEN_BUS
     OpenBus = S9xSA1GetByte (address);
     return (OpenBus | (S9xSA1GetByte (address + 1) << 8));
+#else
+	uint8 Split = S9xSA1GetByte (address);
+	return (Split | (S9xSA1GetByte (address + 1) << 8));
+#endif
 }
 
 void S9xSA1SetByte (uint8 byte, uint32 address)
-- 
cgit v1.2.3