mirror of https://github.com/stella-emu/stella.git
Added a flag to the 6502 code to track if the last memory access was a
read or not. Also modified the TIA code so that if the last access wasn't a read then it does not do a WSYNC operation. This allows the emubug.bin ROM to execute and report "2600" instead of "EMU". git-svn-id: svn://svn.code.sf.net/p/stella/code/trunk@1123 8b62c5a3-ac7e-4cc8-8f21-d9a121418aba
This commit is contained in:
bwmott
parent
ce28361930
commit
ca78e39ca8
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@ -13,7 +13,7 @@
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// See the file "license" for information on usage and redistribution of
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// this file, and for a DISCLAIMER OF ALL WARRANTIES.
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//
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// $Id: TIA.cxx,v 1.68 2006-08-12 02:42:09 bwmott Exp $
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// $Id: TIA.cxx,v 1.69 2006-08-31 02:31:28 bwmott Exp $
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//============================================================================
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#include <cassert>
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@ -2211,8 +2211,18 @@ void TIA::poke(uInt16 addr, uInt8 value)
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case 0x02: // Wait for leading edge of HBLANK
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{
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// Tell the cpu to waste the necessary amount of time
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waitHorizontalSync();
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// It appears that the 6507 only halts during a read cycle so
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// we test here for follow-on writes which should be ignored as
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// far as halting the processor is concerned.
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//
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// TODO - 08-30-2006: This halting isn't correct since it's
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// still halting on the original write. The 6507 emulation
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// should be expanded to include a READY line.
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if(mySystem->m6502().lastAccessWasRead())
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{
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// Tell the cpu to waste the necessary amount of time
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waitHorizontalSync();
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}
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break;
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}
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@ -13,7 +13,7 @@
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// See the file "license" for information on usage and redistribution of
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// this file, and for a DISCLAIMER OF ALL WARRANTIES.
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//
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// $Id: M6502.cxx,v 1.16 2006-06-09 02:45:11 urchlay Exp $
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// $Id: M6502.cxx,v 1.17 2006-08-31 02:31:29 bwmott Exp $
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//============================================================================
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#include "M6502.hxx"
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@ -80,6 +80,9 @@ void M6502::reset()
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SP = 0xff;
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PS(0x20);
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// Reset access flag
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myLastAccessWasRead = true;
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// Load PC from the reset vector
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PC = (uInt16)mySystem->peek(0xfffc) | ((uInt16)mySystem->peek(0xfffd) << 8);
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}
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@ -13,7 +13,7 @@
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// See the file "license" for information on usage and redistribution of
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// this file, and for a DISCLAIMER OF ALL WARRANTIES.
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//
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// $Id: M6502.hxx,v 1.16 2005-12-09 01:16:13 stephena Exp $
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// $Id: M6502.hxx,v 1.17 2006-08-31 02:31:29 bwmott Exp $
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//============================================================================
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#ifndef M6502_HXX
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@ -41,7 +41,7 @@ typedef Common::Array<Expression*> ExpressionList;
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has a 64K addressing space.
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@author Bradford W. Mott
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@version $Id: M6502.hxx,v 1.16 2005-12-09 01:16:13 stephena Exp $
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@version $Id: M6502.hxx,v 1.17 2006-08-31 02:31:29 bwmott Exp $
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*/
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class M6502
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{
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@ -171,6 +171,13 @@ class M6502
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*/
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uInt16 getPC() const { return PC; }
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/**
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Answer true iff the last memory access was a read.
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@return true iff last access was a read.
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*/
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bool lastAccessWasRead() const { return myLastAccessWasRead; }
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public:
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/**
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Overload the ostream output operator for addressing modes.
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@ -279,6 +286,9 @@ class M6502
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/// Table of system cycles for each instruction
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uInt32 myInstructionSystemCycleTable[256];
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/// Indicates if the last memory access was a read or not
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bool myLastAccessWasRead;
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protected:
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/// Addressing mode for each of the 256 opcodes
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static AddressingMode ourAddressingModeTable[256];
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@ -13,7 +13,7 @@
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// See the file "license" for information on usage and redistribution of
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// this file, and for a DISCLAIMER OF ALL WARRANTIES.
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//
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// $Id: M6502Hi.cxx,v 1.15 2005-12-17 01:23:07 stephena Exp $
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// $Id: M6502Hi.cxx,v 1.16 2006-08-31 02:31:29 bwmott Exp $
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//============================================================================
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#include "M6502Hi.hxx"
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@ -62,7 +62,10 @@ inline uInt8 M6502High::peek(uInt16 address)
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}
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#endif
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return mySystem->peek(address);
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uInt8 result = mySystem->peek(address);
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myLastAccessWasRead = true;
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return result;
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}
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// - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
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@ -85,6 +88,7 @@ inline void M6502High::poke(uInt16 address, uInt8 value)
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#endif
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mySystem->poke(address, value);
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myLastAccessWasRead = false;
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}
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// - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
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@ -13,7 +13,7 @@
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// See the file "license" for information on usage and redistribution of
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// this file, and for a DISCLAIMER OF ALL WARRANTIES.
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//
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// $Id: M6502Low.cxx,v 1.8 2006-02-05 02:49:47 stephena Exp $
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// $Id: M6502Low.cxx,v 1.9 2006-08-31 02:31:29 bwmott Exp $
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//============================================================================
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#include "M6502Low.hxx"
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@ -52,7 +52,9 @@ inline uInt8 M6502Low::peek(uInt16 address)
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}
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#endif
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return mySystem->peek(address);
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uInt8 result = mySystem->peek(address);
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myLastAccessWasRead = true;
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return result;
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}
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// - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
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@ -68,6 +70,7 @@ inline void M6502Low::poke(uInt16 address, uInt8 value)
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#endif
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mySystem->poke(address, value);
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myLastAccessWasRead = false;
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}
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// - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
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