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Enhanced class so that it maintains the last value placed on the data bus. 

git-svn-id: svn://svn.code.sf.net/p/stella/code/trunk@12 8b62c5a3-ac7e-4cc8-8f21-d9a121418aba
This commit is contained in:
bwmott 2001-12-30 18:36:02 +00:00
parent 4f214fecfa
commit 7ba178b55b
2 changed files with 35 additions and 9 deletions
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7
stella/src/emucore/m6502/src/System.cxx
View File

@ -8,12 +8,12 @@
// MM MM 66 66 55 55 00 00 22
// MM MM 6666 5555 0000 222222
//
// Copyright (c) 1995-1998 by Bradford W. Mott
// Copyright (c) 1995-2002 by Bradford W. Mott
//
// See the file "license" for information on usage and redistribution of
// this file, and for a DISCLAIMER OF ALL WARRANTIES.
//
// $Id: System.cxx,v 1.1.1.1 2001-12-27 19:54:31 bwmott Exp $
// $Id: System.cxx,v 1.2 2001-12-30 18:36:02 bwmott Exp $
//============================================================================
#include <assert.h>
@ -29,7 +29,8 @@ System::System(uInt16 n, uInt16 m)
myNumberOfPages(1 << (n - m)),
myNumberOfDevices(0),
myM6502(0),
myCycles(0)
myCycles(0),
myDataBusState(0)
{
// Make sure the arguments are reasonable
assert((1 <= m) && (m <= n) && (n <= 16));

37
stella/src/emucore/m6502/src/System.hxx
View File

@ -8,12 +8,12 @@
// MM MM 66 66 55 55 00 00 22
// MM MM 6666 5555 0000 222222
//
// Copyright (c) 1995-1998 by Bradford W. Mott
// Copyright (c) 1995-2002 by Bradford W. Mott
//
// See the file "license" for information on usage and redistribution of
// this file, and for a DISCLAIMER OF ALL WARRANTIES.
//
// $Id: System.hxx,v 1.1.1.1 2001-12-27 19:54:31 bwmott Exp $
// $Id: System.hxx,v 1.2 2001-12-30 18:36:02 bwmott Exp $
//============================================================================
#ifndef SYSTEM_HXX
@ -44,7 +44,7 @@ class NullDevice;
dynamic code for that page of memory.
@author Bradford W. Mott
@version $Id: System.hxx,v 1.1.1.1 2001-12-27 19:54:31 bwmott Exp $
@version $Id: System.hxx,v 1.2 2001-12-30 18:36:02 bwmott Exp $
*/
class System
{
@ -172,7 +172,15 @@ class System
void resetCycles();
public:
/*
/**
Get the current state of the data bus in the system. The current
state is the last data that was accessed by the system.
@return the data bus state
*/
uInt8 getDataBusState() const;
/**
Get the byte at the specified address. No masking of the
address occurs before it's sent to the device mapped at
the address.
@ -267,6 +275,9 @@ class System
// Null device to use for page which are not installed
NullDevice myNullDevice;
// The current state of the Data Bus
uInt8 myDataBusState;
private:
// Copy constructor isn't supported by this class so make it private
System(const System&);
@ -275,20 +286,32 @@ class System
System& operator = (const System&);
};
// - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
inline uInt8 System::getDataBusState() const
{
return myDataBusState;
}
// - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
inline uInt8 System::peek(uInt16 addr)
{
PageAccess& access = myPageAccessTable[(addr & myAddressMask) >> myPageShift];
uInt8 result;
// See if this page uses direct accessing or not
if(access.directPeekBase != 0)
{
return *(access.directPeekBase + (addr & myPageMask));
result = *(access.directPeekBase + (addr & myPageMask));
}
else
{
return access.device->peek(addr);
result = access.device->peek(addr);
}
myDataBusState = result;
return result;
}
// - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
@ -305,6 +328,8 @@ inline void System::poke(uInt16 addr, uInt8 value)
{
access.device->poke(addr, value);
}
myDataBusState = value;
}
#endif