Debugger:

. Move the BRK and invalid opcodes checks out of main emulation's Fetch() and into DebugContinueStepping()
. Added a new break condition: when PC reads floating bus or I/O memory
. On a break condition, output a 'Stop Reason' message to the console

source/CPU.cpp

@@ -102,7 +102,6 @@ Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
 #include "Z80VICE\z80.h"
 #include "Z80VICE\z80mem.h"
 
-#include "Debugger\Debug.h"
 #include "YamlHelper.h"
 
 // 6502 Accumulator Bit Flags
@@ -200,26 +199,9 @@ void SetActiveCpu(eCpuType cpu)
 
 #include "cpu/cpu_instructions.inl"
 
-void RequestDebugger()
-{
-	// BUG: This causes DebugBegin to constantly be called.
-	// It's as if the WM_KEYUP are auto-repeating?
-	//   FrameWndProc()
-	//      ProcessButtonClick()
-	//         DebugBegin()
-	//	PostMessage( g_hFrameWindow, WM_KEYDOWN, DEBUG_TOGGLE_KEY, 0 );
-	//	PostMessage( g_hFrameWindow, WM_KEYUP  , DEBUG_TOGGLE_KEY, 0 );
-
-	// Not a valid solution, since hitting F7 (to exit) debugger gets the debugger out of sync
-	// due to EnterMessageLoop() calling ContinueExecution() after the mode has changed to DEBUG.
-	//	DebugBegin();
-
-	FrameWndProc( g_hFrameWindow, WM_KEYDOWN, DEBUG_TOGGLE_KEY, 0 );
-	FrameWndProc( g_hFrameWindow, WM_KEYUP  , DEBUG_TOGGLE_KEY, 0 );
-}
-
 // Break into debugger on invalid opcodes
-#define INV IsDebugBreakOnInvalid(AM_1);
+//#define INV IsDebugBreakOnInvalid(AM_1);
+#define INV
 
 /****************************************************************************
 *
@@ -373,7 +355,7 @@ static void DebugHddEntrypoint(const USHORT PC)
 }
 #endif
 
-static __forceinline int Fetch(BYTE& iOpcode, ULONG uExecutedCycles)
+static __forceinline void Fetch(BYTE& iOpcode, ULONG uExecutedCycles)
 {
 	const USHORT PC = regs.pc;
 
@@ -385,16 +367,12 @@ static __forceinline int Fetch(BYTE& iOpcode, ULONG uExecutedCycles)
 	    ? IORead[(PC>>4) & 0xFF](PC,PC,0,0,uExecutedCycles)	// Fetch opcode from I/O memory, but params are still from mem[]
 		: *(mem+PC);
 
-	if (IsDebugBreakOpcode( iOpcode ))
-		return 0;
-
 #ifdef USE_SPEECH_API
 	if (PC == COUT && g_Speech.IsEnabled() && !g_bFullSpeed)
 		CaptureCOUT();
 #endif
 
 	regs.pc++;
-	return 1;
 }
 
 //#define ENABLE_NMI_SUPPORT	// Not used - so don't enable

source/CPU/cpu6502.h

@@ -36,7 +36,6 @@ static DWORD Cpu6502(DWORD uTotalCycles, const bool bVideoUpdate)
 	AF_TO_EF
 	ULONG uExecutedCycles = 0;
 	WORD base;
-	g_bDebugBreakpointHit = 0;
 
 	do
 	{
@@ -53,10 +52,10 @@ static DWORD Cpu6502(DWORD uTotalCycles, const bool bVideoUpdate)
 		}
 		else
 		{
-			if (!Fetch(iOpcode, uExecutedCycles))
+			Fetch(iOpcode, uExecutedCycles);
-				break;
 
-#define $ INV // INV = Invalid -> Debugger Break
+//#define $ INV // INV = Invalid -> Debugger Break
+#define $
 			switch (iOpcode)
 			{
 			case 0x00:              BRK  CYC(7)  break;
@@ -335,10 +334,6 @@ static DWORD Cpu6502(DWORD uTotalCycles, const bool bVideoUpdate)
 
 	EF_TO_AF
 
-	if( g_bDebugBreakpointHit )
-		if ((g_nAppMode != MODE_DEBUG) && (g_nAppMode != MODE_STEPPING)) // Running at full speed? (debugger not running)
-			RequestDebugger();
-
 	return uExecutedCycles;
 }
 

source/CPU/cpu65C02.h

@@ -39,7 +39,6 @@ static DWORD Cpu65C02(DWORD uTotalCycles, const bool bVideoUpdate)
 	AF_TO_EF
 	ULONG uExecutedCycles = 0;
 	WORD base;
-	g_bDebugBreakpointHit = 0;
 
 	do
 	{
@@ -56,10 +55,10 @@ static DWORD Cpu65C02(DWORD uTotalCycles, const bool bVideoUpdate)
 		}
 		else
 		{
-			if (!Fetch(iOpcode, uExecutedCycles))
+			Fetch(iOpcode, uExecutedCycles);
-				break;
 
-#define $ INV // INV = Invalid -> Debugger Break
+//#define $ INV // INV = Invalid -> Debugger Break
+#define $
 			switch (iOpcode)
 			{
 			case 0x00:              BRK  CYC(7)  break;
@@ -338,10 +337,6 @@ static DWORD Cpu65C02(DWORD uTotalCycles, const bool bVideoUpdate)
 
 	EF_TO_AF // Emulator Flags to Apple Flags
 
-	if( g_bDebugBreakpointHit )
-		if ((g_nAppMode != MODE_DEBUG) && (g_nAppMode != MODE_STEPPING)) // Running at full speed? (debugger not running)
-			RequestDebugger();
-
 	return uExecutedCycles;
 }
 

source/CPU/cpu65d02.h

@@ -113,7 +113,6 @@ static DWORD Cpu65D02(DWORD uTotalCycles, const bool bVideoUpdate)
 	AF_TO_EF
 	ULONG uExecutedCycles = 0;
 	WORD base;
-	g_bDebugBreakpointHit = 0;
 
 	do
 	{
@@ -132,15 +131,15 @@ static DWORD Cpu65D02(DWORD uTotalCycles, const bool bVideoUpdate)
 
         HEATMAP_X( regs.pc );
 
-		if (!Fetch(iOpcode, uExecutedCycles))
+		Fetch(iOpcode, uExecutedCycles);
-			break;
 
 // INV = Invalid -> Debugger Break
 // MSVC C PreProcessor is BROKEN... #define @ INV
 //#define #    INV
 //#define @    Read()
 //#define $    Store()
-#define $ INV
+//#define $ INV // INV = Invalid -> Debugger Break
+#define $
 
 		switch (iOpcode)
 		{
@@ -423,9 +422,5 @@ static DWORD Cpu65D02(DWORD uTotalCycles, const bool bVideoUpdate)
 
 	EF_TO_AF // Emulator Flags to Apple Flags
 
-	if( g_bDebugBreakpointHit )
-		if ((g_nAppMode != MODE_DEBUG) && (g_nAppMode != MODE_STEPPING)) // // Running at full speed? (debugger not running)
-			RequestDebugger();
-
 	return uExecutedCycles;
 }

source/Debugger/Debug.cpp

@@ -67,8 +67,7 @@ Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
 	int  g_nDebugBreakOnInvalid  = 0; // Bit Flags of Invalid Opcode to break on: // iOpcodeType = AM_IMPLIED (BRK), AM_1, AM_2, AM_3
 	int  g_iDebugBreakOnOpcode   = 0;
 
-	bool g_bDebugBreakDelayCheck = false; // If exiting the debugger, allow at least one instruction to execute so we don't trigger on the same invalid opcode
+	static int  g_bDebugBreakpointHit = 0;	// See: BreakpointHit_t
-	int  g_bDebugBreakpointHit   = 0; // See: BreakpointHit_t
 
 	int  g_nBreakpoints          = 0;
 	Breakpoint_t g_aBreakpoints[ MAX_BREAKPOINTS ];
@@ -868,6 +867,24 @@ _Help:
 
 
 //===========================================================================
+
+// iOpcodeType = AM_IMPLIED (BRK), AM_1, AM_2, AM_3
+static int IsDebugBreakOnInvalid( int iOpcodeType )
+{
+	g_bDebugBreakpointHit |= ((g_nDebugBreakOnInvalid >> iOpcodeType) & 1) ? BP_HIT_INVALID : 0;
+	return g_bDebugBreakpointHit;
+}
+
+// iOpcodeType = AM_IMPLIED (BRK), AM_1, AM_2, AM_3
+static void SetDebugBreakOnInvalid( int iOpcodeType, int nValue )
+{
+	if (iOpcodeType <= AM_3)
+	{
+		g_nDebugBreakOnInvalid &= ~ (          1  << iOpcodeType);
+		g_nDebugBreakOnInvalid |=   ((nValue & 1) << iOpcodeType);
+	}
+}
+
 Update_t CmdBreakInvalid (int nArgs) // Breakpoint IFF Full-speed!
 {
 	if (nArgs > 2) // || (nArgs == 0))
@@ -8469,9 +8486,27 @@ void DebugExitDebugger ()
 }
 
 //===========================================================================
+
+static void CheckBreakOpcode( int iOpcode )
+{
+	if (iOpcode == 0x00)	// BRK
+		IsDebugBreakOnInvalid( AM_IMPLIED );
+
+	if (g_aOpcodes[iOpcode].sMnemonic[0] >= 'a')	// All 6502/65C02 undocumented opcodes mnemonics are lowercase strings!
+	{
+		// TODO: Translate g_aOpcodes[iOpcode].nAddressMode into {AM_1, AM_2, AM_3}
+		IsDebugBreakOnInvalid( AM_1 );
+	}
+
+	// User wants to enter debugger on specific opcode? (NB. Can't be BRK)
+	if (g_iDebugBreakOnOpcode && g_iDebugBreakOnOpcode == iOpcode)
+		g_bDebugBreakpointHit |= BP_HIT_OPCODE;
+}
+
 void DebugContinueStepping ()
 {
 	static unsigned nStepsTaken = 0;
+	static bool bForceSingleStepNext = false; // Allow at least one instruction to execute so we don't trigger on the same invalid opcode
 
 	if (g_nDebugSkipLen > 0)
 	{
@@ -8491,26 +8526,80 @@ void DebugContinueStepping ()
 
 	if (g_nDebugSteps)
 	{
-		if (g_hTraceFile)
+		bool bDoSingleStep = true;
-			OutputTraceLine();
 
-		// Update profiling stats
+		if (bForceSingleStepNext)
 		{
-			BYTE nOpcode = *(mem+regs.pc);
+			bForceSingleStepNext = false;
-			int  nOpmode = g_aOpcodes[ nOpcode ].nAddressMode;
+			g_bDebugBreakpointHit = BP_HIT_NONE;	// Don't show 'Stop Reason' msg a 2nd time
+		}
+		else if (GetActiveCpu() != CPU_Z80)
+		{
+			if (g_hTraceFile)
+				OutputTraceLine();
 
-			g_aProfileOpcodes[ nOpcode ].m_nCount++;
+			g_bDebugBreakpointHit = BP_HIT_NONE;
-			g_aProfileOpmodes[ nOpmode ].m_nCount++;
+
+			bool bPCIsFloatBusOrIO = (regs.pc >= 0xC000 && regs.pc <= 0xC0FF);	// TODO: Determine $C100..CFFF - assume executable
+
+			if (!bPCIsFloatBusOrIO)
+			{
+				BYTE nOpcode = *(mem+regs.pc);
+
+				// Update profiling stats
+				int  nOpmode = g_aOpcodes[ nOpcode ].nAddressMode;
+				g_aProfileOpcodes[ nOpcode ].m_nCount++;
+				g_aProfileOpmodes[ nOpmode ].m_nCount++;
+
+				CheckBreakOpcode( nOpcode );	// Can set g_bDebugBreakpointHit
+			}
+			else
+			{
+				g_bDebugBreakpointHit = BP_HIT_PC_READ_FLOATING_BUS_OR_IO_REG;
+			}
+
+			if (g_bDebugBreakpointHit)
+			{
+				bDoSingleStep = false;
+				bForceSingleStepNext = true;	// Allow next single-step (after this) to execute
+			}
 		}
 
-		SingleStep(g_bGoCmd_ReinitFlag);
+		if (bDoSingleStep)
-		g_bGoCmd_ReinitFlag = false;
+		{
+			SingleStep(g_bGoCmd_ReinitFlag);
+			g_bGoCmd_ReinitFlag = false;
 
-		g_bDebugBreakpointHit |= CheckBreakpointsIO() || CheckBreakpointsReg();
+			g_bDebugBreakpointHit |= CheckBreakpointsIO() || CheckBreakpointsReg();
+		}
+
+		if (regs.pc == g_nDebugStepUntil || g_bDebugBreakpointHit)
+		{
+			TCHAR sText[ CONSOLE_WIDTH ];
+			char* pszStopReason = NULL;
+
+			if (regs.pc == g_nDebugStepUntil)
+				pszStopReason = TEXT("PC matches 'Go until' address");
+			else if (g_bDebugBreakpointHit & BP_HIT_INVALID)
+				pszStopReason = TEXT("Invalid opcode");
+			else if (g_bDebugBreakpointHit & BP_HIT_OPCODE)
+				pszStopReason = TEXT("Opcode match");
+			else if (g_bDebugBreakpointHit & BP_HIT_REG)
+				pszStopReason = TEXT("Register matches value");
+			else if (g_bDebugBreakpointHit & BP_HIT_MEM)
+				pszStopReason = TEXT("Memory accessed");
+			else if (g_bDebugBreakpointHit & BP_HIT_PC_READ_FLOATING_BUS_OR_IO_REG)
+				pszStopReason = TEXT("PC reads from floating bus or I/O register");
+			else
+				pszStopReason = TEXT("Unknown!");
+
+			ConsoleBufferPushFormat( sText, TEXT("Stop reason: %s"), pszStopReason );
+			ConsoleUpdate();
 
-		if ((regs.pc == g_nDebugStepUntil) || g_bDebugBreakpointHit)
 			g_nDebugSteps = 0;
-		else if (g_nDebugSteps > 0)
+		}
+
+		if (g_nDebugSteps > 0)
 			g_nDebugSteps--;
 	}
 
@@ -8525,7 +8614,7 @@ void DebugContinueStepping ()
 		DisasmCalcTopBotAddress();
 
 		Update_t bUpdate = UPDATE_ALL;
-		UpdateDisplay( bUpdate ); // nStepsTaken >= 0x10000);
+		UpdateDisplay( bUpdate );
 		nStepsTaken = 0;
 	}
 }

source/Debugger/Debug.h

@@ -34,6 +34,7 @@
 		,BP_HIT_OPCODE  = (1 << 1)
 		,BP_HIT_REG     = (1 << 2)
 		,BP_HIT_MEM     = (1 << 3)
+		,BP_HIT_PC_READ_FLOATING_BUS_OR_IO_REG = (1 << 4)
 	};
 
 	extern int          g_nBreakpoints;
@@ -42,14 +43,9 @@
 	extern const char  *g_aBreakpointSource [ NUM_BREAKPOINT_SOURCES   ];
 	extern const TCHAR *g_aBreakpointSymbols[ NUM_BREAKPOINT_OPERATORS ];
 
-	// Any Speed Breakpoints
 	extern int  g_nDebugBreakOnInvalid ;
 	extern int  g_iDebugBreakOnOpcode  ;
 
-	// Breakpoint Status
-	extern bool g_bDebugBreakDelayCheck;
-	extern int  g_bDebugBreakpointHit  ;
-
 // Commands
 	void VerifyDebuggerCommandTable();
 
@@ -144,52 +140,6 @@
 
 	bool GetBreakpointInfo ( WORD nOffset, bool & bBreakpointActive_, bool & bBreakpointEnable_ );
 
-	inline int _IsDebugBreakOnOpcode( int iOpcode )
-	{
-		if (g_iDebugBreakOnOpcode == iOpcode)
-			g_bDebugBreakpointHit |= BP_HIT_OPCODE;
-		return g_bDebugBreakpointHit;
-	}
-
-	// iOpcodeType = AM_IMPLIED (BRK), AM_1, AM_2, AM_3
-	inline int IsDebugBreakOnInvalid( int iOpcodeType )
-	{
-		g_bDebugBreakpointHit |= ((g_nDebugBreakOnInvalid >> iOpcodeType) & 1) ? BP_HIT_INVALID : 0;
-		return g_bDebugBreakpointHit;
-	}
-
-	// iOpcodeType = AM_IMPLIED (BRK), AM_1, AM_2, AM_3
-	inline void SetDebugBreakOnInvalid( int iOpcodeType, int nValue )
-	{
-		if (iOpcodeType <= AM_3)
-		{
-			g_nDebugBreakOnInvalid &= ~ (          1  << iOpcodeType);
-			g_nDebugBreakOnInvalid |=   ((nValue & 1) << iOpcodeType);
-		}
-	}
-
-	//
-	// CPU checks the Debugger breakpoints
-	//   a) at opcode fetch
-	//   b) after opcode execution
-	//
-	inline int IsDebugBreakOpcode( int iOpcode )
-	{
-		if (g_bDebugBreakDelayCheck)
-		{
-			g_bDebugBreakDelayCheck = false;
-			return false;
-		}
-
-		if (! iOpcode )
-			IsDebugBreakOnInvalid( AM_IMPLIED );
-
-		if (g_iDebugBreakOnOpcode ) // User wants to enter debugger on specific opcode?
-			_IsDebugBreakOnOpcode(iOpcode);
-
-		return g_bDebugBreakpointHit;
-	}
-	
 // Source Level Debugging
 	int FindSourceLine( WORD nAddress );
 	const char* FormatAddress( WORD nAddress, int nBytes );

source/Frame.cpp

@@ -1898,7 +1898,6 @@ static void ProcessButtonClick(int button, bool bFromButtonUI /*=false*/)
 		else
 		if (g_nAppMode == MODE_DEBUG)
 		{
-			g_bDebugBreakDelayCheck = true;
 			ProcessButtonClick(BTN_RUN); // Exit debugger, switch to MODE_RUNNING or MODE_STEPPING
 		}
 		else

test/TestCPU6502/TestCPU6502.cpp

@@ -14,15 +14,6 @@ LPBYTE         memdirty     = NULL;	// TODO: Init
 iofunction		IORead[256] = {0};	// TODO: Init
 iofunction		IOWrite[256] = {0};	// TODO: Init
 
-// From Debugger_Types.h
-	enum AddressingMode_e // ADDRESSING_MODES_e
-	{
-		  AM_IMPLIED // Note: SetDebugBreakOnInvalid() assumes this order of first 4 entries
-		, AM_1    //    Invalid 1 Byte
-		, AM_2    //    Invalid 2 Bytes
-		, AM_3    //    Invalid 3 Bytes
-	};
-
 // From CPU.cpp
 #define	 AF_SIGN       0x80
 #define	 AF_OVERFLOW   0x40
@@ -58,12 +49,6 @@ static __forceinline int Fetch(BYTE& iOpcode, ULONG uExecutedCycles)
 	return 1;
 }
 
-#define INV IsDebugBreakOnInvalid(AM_1);
-inline int IsDebugBreakOnInvalid( int iOpcodeType )
-{
-	return 0;
-}
-
 static __forceinline void DoIrqProfiling(DWORD uCycles)
 {
 }
@@ -80,19 +65,6 @@ static __forceinline void IRQ(ULONG& uExecutedCycles, BOOL& flagc, BOOL& flagn,
 {
 }
 
-void RequestDebugger()
-{
-}
-
-// From Debug.h
-inline int IsDebugBreakpointHit()
-{
-	return 0;
-}
-
-// From Debug.cpp
-int g_bDebugBreakpointHit = 0;
-
 // From z80.cpp
 DWORD z80_mainloop(ULONG uTotalCycles, ULONG uExecutedCycles)
 {