HALT and BREAK instructions

Two special opcodes have been implemeted - 0x15 (AKA HALT) and 0x113E (aka BREAK).
The BREAK opcode is supported by lwasm while the HALT opcode is an unused 6x09
single byte instruction.  When enabled Vcc will halt (pause) the CPU when one of
these codes is encountered. The ability to enable/disable these opcodes has been
added to the CPU config screen and these settings are preserved in the Vcc ini file.

Debugger.cpp

@@ -477,6 +477,47 @@ namespace VCC { namespace Debugger
 		MemWrite8(memWrite.value, memWrite.addr);
 	}
 
+	// Check of halt instruction is enabled
+	bool Debugger::Halt_Enabled(int Hinstr)
+	{
+		switch (Hinstr) {
+		case 0x15:
+			return Halt_0x15_TF;
+		case 0x113E:
+			return Halt_0x113E_TF;
+		default:
+			return false;
+		}
+	}
+
+	// DoHalt halts emulation and returns the number of opcodes
+	// used or zero if a breakpoint. A breakpoint will restore
+	// the original instruction which will execute next. The PC
+	// will be used as the key to the breakpoints list
+		int Debugger::DoHalt(int Hinstr,unsigned short /*PC*/) {
+		Debugger::Halt();
+		switch (Hinstr) {
+		case 0x15:		//Vcc HALT
+			return 1;
+		case 0x113E:	//Vcc BREAK
+			return 2;
+		default:
+			return 1;
+		}
+	}
+
+	// Enable / Disable halt instruction
+	void Debugger::EnableHalt(int Hinstr, bool enable)
+	{
+		switch (Hinstr) {
+		case 0x15:
+			Halt_0x15_TF = enable;
+			break;
+		case 0x113E:
+			Halt_0x113E_TF = enable;
+			break;
+		}
+	}
 
 } }
 

Debugger.h

@@ -103,6 +103,22 @@ namespace VCC { namespace Debugger
 
 		void Update();
 
+		// VCC halt instuction status and enable.  Halt_0x113E is a "BREAK"
+		// instruction that can be compiled into code for debugging purposes.
+		// Halt_0x15 is a "HALT" instruction.  VCC could use "HALT" as a breakpoint
+		// mechanism. A breakpoint would be established by replacing an opcode by
+		// HALT and saving the replaced opcode in a table indexed by the program
+		// counter. When the halt is encountered the original opcode is restored
+		// and will execute next.  If the breakpoint is to be persistant the HALT
+		// will need to be replaced after the original instruction executes. NOTE:
+		// The current Debugger Breakpoints screen does not use this mechanism. It
+		// searches for a program counter match in a table before executing each
+		// instruction, which slows execution. A future TODO is to use this new
+		// mechanism instead for that screen.
+		bool Halt_Enabled(int);
+		void EnableHalt(int,bool);
+		int DoHalt(int,unsigned short);
+
 	protected:
 
 		enum class ExecutionMode
@@ -156,5 +172,7 @@ namespace VCC { namespace Debugger
 		bool							TraceTriggerChanged_ = false;
 		tracebuffer_type				TraceCaptured_;
 		std::map<int, long>				TraceMarks_;
+		bool							Halt_0x113E_TF = false;
+		bool							Halt_0x15_TF = false;
 	};
 } }

OpCodeTables.h

@@ -102,7 +102,7 @@ namespace VCC { namespace Debugger
 			0x12,	"NOP",		Inherent,		2,		1,		1,		1,	false,	Fixed,
 			0x13,	"SYNC",		Inherent,		4,		3,		1,		1,	false,	WaitForSYNCAdjust,
 			0x14,	"SEXW",		Inherent,		4,		4,		1,		1,	true,	Fixed,						// Illegal on 6809
-			0x15,	"-",		Illegal,		0,		0,		0,		1,	false,	None,
+			0x15,	"HALT",		Inherent,		2,		1,		1,		1,	false,	Fixed,
 			0x16,	"LBRA",		LongRelative,	5,		4,		3,		1,	false,	LongBranchAdjust,
 			0x17,	"LBSR",		LongRelative,	9,		7,		3,		1,	false,	LongBranchAdjust,
 			0x18,	"-",		Illegal,		0,		0,		0,		1,	false,	None,
@@ -697,7 +697,7 @@ namespace VCC { namespace Debugger
 			0x3B,	"TFM",		Immediate,		6,		6,		3,		2,	true,	TFMAdjust,					// Illegal on 6809
 			0x3C,	"BITMD",	Immediate,		4,		4,		3,		2,	true,	Fixed,						// Illegal on 6809
 			0x3D,	"LDMD",		Immediate,		5,		5,		3,		2,	true,	Fixed,						// Illegal on 6809
-			0x3E,	"-",		Illegal,		0,		0,		0,		2,	false,	None,
+			0x3E,	"BREAK",	Inherent,		4,		2,		2,		2,	false,	Fixed,
 			0x3F,	"SWI3",		Inherent,		20,		22,		2,		2,	false,	Fixed,
 
 			0x40,	"-",		Illegal,		0,		0,		0,		2,	false,	None,

Vcc.rc

@@ -201,18 +201,21 @@ IDD_CPU DIALOGEX 0, 0, 268, 217
 STYLE DS_SETFONT | WS_CHILD
 FONT 8, "MS Sans Serif", 0, 0, 0x1
 BEGIN
+    GROUPBOX        "Memory Size",IDC_STATIC,17,60,60,54,BS_CENTER
     CONTROL         "Slider1",IDC_CLOCKSPEED,"msctls_trackbar32",TBS_TOP | TBS_NOTICKS | WS_TABSTOP,17,30,176,15,WS_EX_CLIENTEDGE
     EDITTEXT        IDC_CLOCKDISPLAY,199,30,45,15,ES_AUTOHSCROLL | ES_READONLY
     GROUPBOX        "Over-Clocking",IDC_STATIC,15,19,234,34,BS_CENTER
-    ICON            "",IDC_CPUICON,143,140,21,20
-    RADIOBUTTON     "Motorola MC6809 CPU",IDC_6809,27,139,89,10
-    RADIOBUTTON     "Hitachi HD6309 CPU",IDC_6309,27,152,87,10,WS_TABSTOP
-    GROUPBOX        "Memory Size",IDC_STATIC,17,60,60,54,BS_CENTER
     RADIOBUTTON     "128 K",IDC_128K,27,71,35,10
     RADIOBUTTON     "512 K",IDC_512K,27,81,35,10
     RADIOBUTTON     "2048 K",IDC_2M,27,92,39,10
     RADIOBUTTON     "8192 K",IDC_8M,27,103,39,10
-    GROUPBOX        "CPU",IDC_STATIC,17,123,156,44,BS_CENTER
+    GROUPBOX        "CPU",IDC_STATIC,17,123,154,43,BS_CENTER
+    RADIOBUTTON     "Motorola MC6809 CPU",IDC_6809,27,137,89,10
+    RADIOBUTTON     "Hitachi HD6309 CPU",IDC_6309,27,150,87,10,WS_TABSTOP
+    ICON            "",IDC_CPUICON,140,138,21,20
+	GROUPBOX		"VCC Debug Opcodes",IDC_STATIC,17,174,120,43,BS_CENTER
+    CONTROL         "HALT    ($15)",IDC_ENABLE_HALT, "Button",BS_AUTOCHECKBOX | WS_TABSTOP,27,188,70,10
+    CONTROL         "BREAK ($113E)",IDC_ENABLE_BREAK,"Button",BS_AUTOCHECKBOX | WS_TABSTOP,27,200,70,10
 END
 
 IDD_AUDIO DIALOGEX 0, 0, 269, 160

config.c

@@ -240,6 +240,8 @@ unsigned char WriteIniFile(void)
 	WritePrivateProfileInt("CPU","Throttle",CurrentConfig.SpeedThrottle,IniFilePath);
 	WritePrivateProfileInt("CPU","CpuType",CurrentConfig.CpuType,IniFilePath);
 	WritePrivateProfileInt("CPU", "MaxOverClock", CurrentConfig.MaxOverclock, IniFilePath);
+	WritePrivateProfileInt("CPU","HaltEnabled",CurrentConfig.HaltOpcEnabled,IniFilePath);
+	WritePrivateProfileInt("CPU","BreakEnabled",CurrentConfig.BreakOpcEnabled,IniFilePath);
 
 	WritePrivateProfileString("Audio","SndCard",CurrentConfig.SoundCardName,IniFilePath);
 	WritePrivateProfileInt("Audio","Rate",CurrentConfig.AudioRate,IniFilePath);
@@ -299,7 +301,9 @@ unsigned char ReadIniFile(void)
 	CurrentConfig.FrameSkip = GetPrivateProfileInt("CPU","FrameSkip",1,IniFilePath);
 	CurrentConfig.SpeedThrottle = GetPrivateProfileInt("CPU","Throttle",1,IniFilePath);
 	CurrentConfig.CpuType = GetPrivateProfileInt("CPU","CpuType",0,IniFilePath);
-	CurrentConfig.MaxOverclock = GetPrivateProfileInt("CPU", "MaxOverClock",100, IniFilePath);
+	CurrentConfig.MaxOverclock = GetPrivateProfileInt("CPU","MaxOverClock",100,IniFilePath);
+	CurrentConfig.HaltOpcEnabled = GetPrivateProfileInt("CPU","HaltEnabled",0,IniFilePath);
+	CurrentConfig.BreakOpcEnabled = GetPrivateProfileInt("CPU","BreakEnabled",0,IniFilePath);
 
 	CurrentConfig.AudioRate = GetPrivateProfileInt("Audio","Rate",3,IniFilePath);
 	GetPrivateProfileString("Audio","SndCard","",CurrentConfig.SoundCardName,63,IniFilePath);
@@ -547,6 +551,18 @@ void UpdateConfig (void)
 	SetCPUMultiplyer(CurrentConfig.CPUMultiplyer);
 	SetRamSize(CurrentConfig.RamSize);
 	SetCpuType(CurrentConfig.CpuType);
+
+	if (CurrentConfig.HaltOpcEnabled) {
+		EmuState.Debugger.EnableHalt(0x15,true);
+	} else {
+		EmuState.Debugger.EnableHalt(0x15,false);
+	}
+	if (CurrentConfig.BreakOpcEnabled) {
+		EmuState.Debugger.EnableHalt(0x113E,true);
+	} else {
+		EmuState.Debugger.EnableHalt(0x113E,false);
+	}
+
 	SetMonitorType(CurrentConfig.MonitorType);
 	SetCartAutoStart(CurrentConfig.CartAutoStart);
 	if (CurrentConfig.RebootNow)
@@ -622,6 +638,8 @@ LRESULT CALLBACK CpuConfig(HWND hDlg, UINT message, WPARAM wParam, LPARAM lParam
 			for (temp=0;temp<=1;temp++)
 				SendDlgItemMessage(hDlg,Cpuchoice[temp],BM_SETCHECK,(temp==TempConfig.CpuType),0);
 			SendDlgItemMessage(hDlg,IDC_CPUICON,STM_SETIMAGE ,(WPARAM)IMAGE_ICON,(LPARAM)CpuIcons[TempConfig.CpuType]);
+			SendDlgItemMessage(hDlg,IDC_ENABLE_HALT,BM_SETCHECK,TempConfig.HaltOpcEnabled,0);
+			SendDlgItemMessage(hDlg,IDC_ENABLE_BREAK,BM_SETCHECK,TempConfig.BreakOpcEnabled,0);
 		break;
 
 		case WM_HSCROLL:
@@ -659,6 +677,15 @@ LRESULT CALLBACK CpuConfig(HWND hDlg, UINT message, WPARAM wParam, LPARAM lParam
 							SendDlgItemMessage(hDlg,IDC_CPUICON,STM_SETIMAGE ,(WPARAM)IMAGE_ICON,(LPARAM)CpuIcons[TempConfig.CpuType]);
 						}
 				break;
+				case IDC_ENABLE_HALT:
+					TempConfig.HaltOpcEnabled = (unsigned char)
+						SendDlgItemMessage(hDlg,IDC_ENABLE_HALT,BM_GETCHECK,0,0);
+				break;
+				case IDC_ENABLE_BREAK:
+					TempConfig.BreakOpcEnabled = (unsigned char)
+						SendDlgItemMessage(hDlg,IDC_ENABLE_BREAK,BM_GETCHECK,0,0);
+				break;
+
 			}	//End switch LOWORD(wParam)
 		break;	//Break WM_COMMAND
 	}			//END switch (message)
@@ -707,9 +734,9 @@ LRESULT CALLBACK TapeConfig(HWND hDlg, UINT message, WPARAM wParam, LPARAM lPara
 			SendDlgItemMessage(hDlg,IDC_TAPEFILE,WM_SETTEXT,strlen(TapeFileName),(LPARAM)(LPCSTR)TapeFileName);
 //			hCounter=GetDlgItem(hDlg,IDC_TCOUNT);
 //			SendMessage (hCounter, EM_SETBKGNDCOLOR, 0, (LPARAM)RGB(0,0,0));
-			SendDlgItemMessage(hDlg,IDC_TCOUNT,EM_SETBKGNDCOLOR ,0,(LPARAM)RGB(0,0,0)); 
+			SendDlgItemMessage(hDlg,IDC_TCOUNT,EM_SETBKGNDCOLOR ,0,(LPARAM)RGB(0,0,0));
 			SendDlgItemMessage(hDlg,IDC_TCOUNT,EM_SETCHARFORMAT ,SCF_ALL,(LPARAM)&CounterText);
-			SendDlgItemMessage(hDlg,IDC_MODE,EM_SETBKGNDCOLOR ,0,(LPARAM)RGB(0,0,0)); 
+			SendDlgItemMessage(hDlg,IDC_MODE,EM_SETBKGNDCOLOR ,0,(LPARAM)RGB(0,0,0));
 			SendDlgItemMessage(hDlg,IDC_MODE,EM_SETCHARFORMAT ,SCF_ALL,(LPARAM)&CounterText);
 //			SendDlgItemMessage(hDlg,IDC_MODE,EM_SETCHARFORMAT ,SCF_ALL,(LPARAM)&ModeText);
 			hDlgTape=hDlg;
@@ -767,7 +794,7 @@ LRESULT CALLBACK AudioConfig(HWND hDlg, UINT message, WPARAM wParam, LPARAM lPar
 			SendDlgItemMessage(hDlg,IDC_PROGRESSRIGHT,PBM_SETRANGE32,0,0x7F);
 			SendDlgItemMessage(hDlg,IDC_PROGRESSLEFT,PBM_SETPOS,0,0);
 			SendDlgItemMessage(hDlg,IDC_PROGRESSLEFT,PBM_SETBARCOLOR,0,0xFFFF); //bgr 
-			SendDlgItemMessage(hDlg,IDC_PROGRESSRIGHT,PBM_SETBARCOLOR,0,0xFFFF); 
+			SendDlgItemMessage(hDlg,IDC_PROGRESSRIGHT,PBM_SETBARCOLOR,0,0xFFFF);
 			SendDlgItemMessage(hDlg,IDC_PROGRESSLEFT,PBM_SETBKCOLOR,0,0);
 			SendDlgItemMessage(hDlg,IDC_PROGRESSRIGHT,PBM_SETBKCOLOR,0,0);
 			for (Index=0;Index<NumberOfSoundCards;Index++)

config.h

@@ -49,6 +49,8 @@ typedef struct  {
 	unsigned char	FrameSkip;
 	unsigned char	SpeedThrottle;
 	unsigned char	CpuType;
+	unsigned char	HaltOpcEnabled;   // 0x15   halt enabled
+	unsigned char	BreakOpcEnabled;  // 0x113E halt enabled
 //	unsigned char	AudioMute;
 	unsigned char	MonitorType;
 	unsigned char   PaletteType;

hd6309.c

@@ -6205,6 +6205,26 @@ void Stu_E(void)
 	CycleCounter+=NatEmuCycles65;
 }
 
+void Halt_15(void)
+{ //15
+	if (EmuState.Debugger.Halt_Enabled(0x15)) {
+		PC_REG += EmuState.Debugger.DoHalt(0x15,PC_REG);
+	} else {
+		PC_REG+=1;
+		CycleCounter+=NatEmuCycles21;
+	}
+}
+
+void Halt_113E(void)
+{ //113E
+	if (EmuState.Debugger.Halt_Enabled(0x113E)) {
+		PC_REG += EmuState.Debugger.DoHalt(0x113E,PC_REG);
+	} else {
+		PC_REG+=2;
+		CycleCounter+=NatEmuCycles21;
+	}
+}
+
 void(*JmpVec1[256])(void) = {
 	Neg_D,		// 00
 	Oim_D,		// 01
@@ -6227,7 +6247,7 @@ void(*JmpVec1[256])(void) = {
 	Nop_I,		// 12
 	Sync_I,		// 13
 	Sexw_I,		// 14
-	InvalidInsHandler,	// 15
+	Halt_15,    // 15
 	Lbra_R,		// 16
 	Lbsr_R,		// 17
 	InvalidInsHandler,	// 18
@@ -6786,7 +6806,7 @@ void(*JmpVec3[256])(void) = {
 	Tfm4,		// 3B
 	Bitmd_M,	// 3C
 	Ldmd_M,		// 3D
-	InvalidInsHandler,		// 3E
+	Halt_113E,  // 3E
 	Swi3_I,		// 3F
 	InvalidInsHandler,		// 40
 	InvalidInsHandler,		// 41

hd6309defs.h

@@ -71,6 +71,7 @@ This file is part of VCC (Virtual Color Computer).
 #define NOP_I	0x12
 #define SYNC_I	0x13
 #define SEXW_I	0x14		//6309	
+#define HALT	0x15		//Vcc Halt_0x15
 #define LBRA_R	0x16
 #define LBSR_R	0x17
 #define DAA_I	0x19
@@ -438,6 +439,7 @@ This file is part of VCC (Virtual Color Computer).
 #define TFM4	0x3B	//6309
 #define	BITMD_M	0x3C	//6309
 #define LDMD_M	0x3D	//6309
+#define BREAK	0x3E    //VCC Halt_0x113e
 #define SWI3_I	0x3F
 #define COME_I	0x43	//6309
 #define DECE_I	0x4A	//6309

mc6809.c

@@ -747,6 +747,16 @@ case	Page3:
 
 		switch (MemRead8(pc.Reg++))
 		{
+		case BREAK: //113E
+			if (EmuState.Debugger.Halt_Enabled(0x15)) {
+				if (EmuState.Debugger.DoHalt(0x15,PC_REG) == 0) {
+					pc.Reg = pc.Reg - 2;
+				}
+			} else {
+				CycleCounter+=4;
+			}
+			break;
+
 		case SWI3_I: //113F
 			cc[E]=1;
 			MemWrite8( pc.B.lsb,--s.Reg);
@@ -865,6 +875,16 @@ case SYNC_I: //13
 	SyncWaiting=1;
 	break;
 
+case HALT: //15
+	if (EmuState.Debugger.Halt_Enabled(0x15)) {
+		if (EmuState.Debugger.DoHalt(0x15,PC_REG) == 0) {
+			pc.Reg = pc.Reg - 1;
+		}
+	} else {
+		CycleCounter+=4;
+	}
+	break;
+
 case LBRA_R: //16
 	*spostword=MemRead16(pc.Reg);
 	pc.Reg+=2;

mc6809defs.h

@@ -54,6 +54,7 @@ This file is part of VCC (Virtual Color Computer).
 #define	Page3	0x11
 #define NOP_I	0x12
 #define SYNC_I	0x13
+#define HALT	0x15	// Vcc Halt_15
 #define LBRA_R	0x16
 #define LBSR_R	0x17
 #define DAA_I	0x19
@@ -320,6 +321,7 @@ This file is part of VCC (Virtual Color Computer).
 #define STS_E	0xFF
 
 //*******************Page 3 Codes*********************************
+#define BREAK	0x3E	// Vcc Halt_113E
 #define SWI3_I	0x3F
 #define CMPU_M	0x83
 #define CMPS_M	0x8C

resource.h

@@ -381,6 +381,8 @@
 #define IDC_EDIT_BLOCK                  2138
 #define IDC_ADRTXT                      2139
 #define IDC_BTN_OS9                     2140
+#define IDC_ENABLE_HALT                 2141
+#define IDC_ENABLE_BREAK                2142
 
 #define IDM_USER_WIKI                   40001
 #define ID_FILE_EXIT                    40002
@@ -432,7 +434,7 @@
 #ifndef APSTUDIO_READONLY_SYMBOLS
 #define _APS_NEXT_RESOURCE_VALUE        176
 #define _APS_NEXT_COMMAND_VALUE         40047
-#define _APS_NEXT_CONTROL_VALUE         2142
+#define _APS_NEXT_CONTROL_VALUE         2145
 #define _APS_NEXT_SYMED_VALUE           101
 #endif
 #endif