lots of arm710a fixes

WindCore/arm710a.cpp

@@ -104,6 +104,7 @@ uint32_t ARM710a::tick() {
 		if (insnFault != NoFault) {
 			// Raise a prefetch error
 			// These do not set FSR or FAR
+			log("prefetch error!");
 			raiseException(Abort32, GPRs[15] - 8, 0xC);
 		} else {
 			clocks += executeInstruction(insn);
@@ -131,6 +132,7 @@ static inline bool extract1(uint32_t value, uint32_t bit) {
 
 uint32_t ARM710a::executeInstruction(uint32_t i) {
 	uint32_t cycles = 1;
+//	log("executing insn %08x @ %08x", i, GPRs[15] - 0xC);
 
 	// a big old dispatch thing here
 	// but first, conditions!
@@ -191,59 +193,64 @@ uint32_t ARM710a::execDataProcessing(bool I, uint32_t Opcode, bool S, uint32_t R
 				op2 -= 4;
 		}
 
-		switch (extract(Operand2, 6, 5)) {
+		if (extract(Operand2, 4, 4) && (shiftBy == 0)) {
-		case 0: // Logical Left (LSL)
+			// register shift by 0 never does anything
-			if (shiftBy == 0) {
+			shifterCarryOutput = flagC();
-				shifterCarryOutput = flagC();
+		} else {
-				// no change to op2!
+			switch (extract(Operand2, 6, 5)) {
-			} else if (shiftBy <= 31) {
+			case 0: // Logical Left (LSL)
-				shifterCarryOutput = extract1(op2, 31 - shiftBy);
+				if (shiftBy == 0) {
-				op2 <<= shiftBy;
+					shifterCarryOutput = flagC();
-			} else if (shiftBy == 32) {
+					// no change to op2!
-				shifterCarryOutput = extract1(op2, 0);
+				} else if (shiftBy <= 31) {
-				op2 = 0;
+					shifterCarryOutput = extract1(op2, 31 - shiftBy);
-			} else /*if (shiftBy >= 33)*/ {
+					op2 <<= shiftBy;
-				shifterCarryOutput = false;
+				} else if (shiftBy == 32) {
-				op2 = 0;
+					shifterCarryOutput = extract1(op2, 0);
-			}
+					op2 = 0;
-			break;
+				} else /*if (shiftBy >= 33)*/ {
-		case 1: // Logical Right (LSR)
+					shifterCarryOutput = false;
-			if (shiftBy == 0 || shiftBy == 32) {
+					op2 = 0;
-				shifterCarryOutput = extract1(op2, 31);
-				op2 = 0;
-			} else if (shiftBy <= 31) {
-				shifterCarryOutput = extract1(op2, shiftBy - 1);
-				op2 >>= shiftBy;
-			} else /*if (shiftBy >= 33)*/ {
-				shifterCarryOutput = false;
-				op2 = 0;
-			}
-			break;
-		case 2: // Arithmetic Right (ASR)
-			if (shiftBy == 0 || shiftBy >= 32) {
-				shifterCarryOutput = extract1(op2, 31);
-				op2 = (int32_t)op2 >> 31;
-			} else /*if (shiftBy <= 31)*/ {
-				shifterCarryOutput = extract1(op2, shiftBy - 1);
-				op2 = (int32_t)op2 >> shiftBy;
-			}
-			break;
-		case 3: // Rotate Right (ROR)
-			if (shiftBy == 0) { // treated as RRX
-				shifterCarryOutput = op2 & 1;
-				op2 >>= 1;
-				op2 |= flagC() ? 0x80000000 : 0;
-			} else {
-				shiftBy %= 32;
-				if (shiftBy == 0) { // like 32
-					shifterCarryOutput = extract1(op2, 31);
-					// no change to op2
-				} else {
-					shifterCarryOutput = extract1(op2, shiftBy - 1);
-					op2 = ROR(op2, shiftBy);
 				}
+				break;
+			case 1: // Logical Right (LSR)
+				if (shiftBy == 0 || shiftBy == 32) {
+					shifterCarryOutput = extract1(op2, 31);
+					op2 = 0;
+				} else if (shiftBy <= 31) {
+					shifterCarryOutput = extract1(op2, shiftBy - 1);
+					op2 >>= shiftBy;
+				} else /*if (shiftBy >= 33)*/ {
+					shifterCarryOutput = false;
+					op2 = 0;
+				}
+				break;
+			case 2: // Arithmetic Right (ASR)
+				if (shiftBy == 0 || shiftBy >= 32) {
+					shifterCarryOutput = extract1(op2, 31);
+					op2 = (int32_t)op2 >> 31;
+				} else /*if (shiftBy <= 31)*/ {
+					shifterCarryOutput = extract1(op2, shiftBy - 1);
+					op2 = (int32_t)op2 >> shiftBy;
+				}
+				break;
+			case 3: // Rotate Right (ROR)
+				if (shiftBy == 0) { // treated as RRX
+					shifterCarryOutput = op2 & 1;
+					op2 >>= 1;
+					op2 |= flagC() ? 0x80000000 : 0;
+				} else {
+					shiftBy %= 32;
+					if (shiftBy == 0) { // like 32
+						shifterCarryOutput = extract1(op2, 31);
+						// no change to op2
+					} else {
+						shifterCarryOutput = extract1(op2, shiftBy - 1);
+						op2 = ROR(op2, shiftBy);
+					}
+				}
+				break;
 			}
-			break;
 		}
 	} else {
 		// IMMEDIATE
@@ -252,7 +259,6 @@ uint32_t ARM710a::execDataProcessing(bool I, uint32_t Opcode, bool S, uint32_t R
 
 		uint32_t Rotate = extract(Operand2, 11, 8);
 		uint32_t Imm = extract(Operand2, 7, 0);
-		Imm = (uint32_t)(int8_t)Imm;
 		op2 = ROR(Imm, Rotate * 2);
 		shifterCarryOutput = flagC(); // correct? unsure...
 	}
@@ -269,7 +275,7 @@ uint32_t ARM710a::execDataProcessing(bool I, uint32_t Opcode, bool S, uint32_t R
 	flags |= (CPSR & CPSR_V);
 
 #define ADD_OP(a, b, c) \
-	result = a + b + (uint32_t)(c); \
+	result = (uint64_t)(a) + (uint64_t)(b) + (uint64_t)(c); \
 	flags |= (result & 0xFFFFFFFF) ? 0 : CPSR_Z; \
 	flags |= (result & 0x80000000) ? CPSR_N : 0; \
 	flags |= (result & 0x100000000) ? CPSR_C : 0; \
@@ -301,9 +307,11 @@ uint32_t ARM710a::execDataProcessing(bool I, uint32_t Opcode, bool S, uint32_t R
 		// Output-less opcodes: special behaviour
 		if (S) {
 			CPSR = (CPSR & ~CPSR_FlagMask) | flags;
+//			log("CPSR setflags=%08x results in CPSR=%08x", flags, CPSR);
 		} else if (Opcode == 8) {
 			// MRS, CPSR -> Reg
 			GPRs[Rd] = CPSR;
+			log("r%d <- CPSR(%08x)", Rd, GPRs[Rd]);
 		} else if (Opcode == 9) {
 			// MSR, Reg -> CPSR
 			bool canChangeMode = extract1(Rn, 0);
@@ -311,27 +319,33 @@ uint32_t ARM710a::execDataProcessing(bool I, uint32_t Opcode, bool S, uint32_t R
 				auto newCPSR = GPRs[extract(Operand2, 3, 0)];
 				switchMode(modeFromCPSR(newCPSR));
 				CPSR = newCPSR;
+				log("CPSR change privileged: %08x", CPSR);
 			} else {
 				// for the flag-only version, immediates are allowed
 				// so we just re-use what was calculated earlier...
 				auto newFlag = I ? op2 : GPRs[extract(Operand2, 3, 0)];
 				CPSR &= ~CPSR_FlagMask;
 				CPSR |= (newFlag & CPSR_FlagMask);
+				log("CPSR change unprivileged: new=%08x result=%08x", newFlag, CPSR);
 			}
 		} else if (Opcode == 0xA) {
 			// MRS, SPSR -> Reg
-			if (isPrivileged())
+			if (isPrivileged()) {
 				GPRs[Rd] = SPSRs[currentBank()];
+				log("r%d <- SPSR(%08x)", Rd, GPRs[Rd]);
+			}
 		} else /*if (Opcode == 0xB)*/ {
 			bool canChangeMode = extract1(Rn, 0);
 			if (isPrivileged()) {
 				if (canChangeMode) {
 					SPSRs[currentBank()] = GPRs[extract(Operand2, 3, 0)];
+					log("SPSR change privileged: %08x", SPSRs[currentBank()]);
 				} else {
 					// same hat
 					auto newFlag = I ? op2 : GPRs[extract(Operand2, 3, 0)];
 					SPSRs[currentBank()] &= ~CPSR_FlagMask;
 					SPSRs[currentBank()] |= (newFlag & CPSR_FlagMask);
+					log("SPSR change unprivileged: new=%08x result=%08x", newFlag, SPSRs[currentBank()]);
 				}
 			}
 		}
@@ -348,9 +362,11 @@ uint32_t ARM710a::execDataProcessing(bool I, uint32_t Opcode, bool S, uint32_t R
 				auto saved = SPSRs[currentBank()];
 				switchMode(modeFromCPSR(saved));
 				CPSR = saved;
+				log("dataproc restore CPSR: %08x", CPSR);
 			}
 		} else if (S) {
 			CPSR = (CPSR & ~CPSR_FlagMask) | flags;
+//			log("dataproc flag change: flags=%08x CPSR=%08x", flags, CPSR);
 		}
 	}
 
@@ -400,7 +416,7 @@ uint32_t ARM710a::execSingleDataTransfer(uint32_t IPUBWL, uint32_t Rn, uint32_t
 	auto valueSize = extract1(IPUBWL, 2) ? V8 : V32;
 	bool up = extract1(IPUBWL, 3);
 	bool preIndex = extract1(IPUBWL, 4);
-	bool immediate = extract1(IPUBWL, 5);
+	bool immediate = !extract1(IPUBWL, 5);
 
 	// calculate the offset
 	uint32_t calcOffset;
@@ -438,10 +454,8 @@ uint32_t ARM710a::execSingleDataTransfer(uint32_t IPUBWL, uint32_t Rn, uint32_t
 		}
 	} else {
 		// IMMEDIATE
-		uint32_t Rotate = extract(offset, 11, 8);
+		// No rotation or anything here
-		uint32_t Imm = extract(offset, 7, 0);
+		calcOffset = offset;
-		Imm = (uint32_t)(int8_t)Imm;
-		calcOffset = ROR(Imm, Rotate * 2);
 	}
 
 	uint32_t base = GPRs[Rn];
@@ -458,8 +472,10 @@ uint32_t ARM710a::execSingleDataTransfer(uint32_t IPUBWL, uint32_t Rn, uint32_t
 		if (changeModes) switchMode(User32);
 		auto readResult = readVirtual(transferAddr, valueSize);
 		if (changeModes) switchMode(saveMode);
-		if (readResult.first.has_value())
+		if (readResult.first.has_value()) {
 			GPRs[Rd] = readResult.first.value();
+			if (Rd == 15) prefetchCount = 0;
+		}
 		fault = readResult.second;
 	} else {
 		uint32_t value = GPRs[Rd];
@@ -538,6 +554,9 @@ uint32_t ARM710a::execBlockDataTransfer(uint32_t PUSWL, uint32_t Rn, uint32_t re
 		}
 	}
 
+	if (registerList & 0x8000)
+		prefetchCount = 0;
+
 	// datasheet specifies that base register must be
 	// restored if an error occurs during LDM
 	if (load && fault != NoFault)
@@ -741,7 +760,7 @@ pair<MaybeU32, ARM710a::MMUFault> ARM710a::readVirtual(uint32_t virtAddr, ValueS
 		if (auto v = readPhysical(virtAddr, valueSize); v.has_value())
 			return make_pair(v.value(), NoFault);
 		else
-			return make_pair(MaybeU32(), NonMMUError);
+			return make_pair(MaybeU32(), encodeFault(NonMMUError, 0, virtAddr));
 	}
 
 	auto translated = translateAddressUsingTlb(virtAddr);
@@ -775,7 +794,7 @@ ARM710a::MMUFault ARM710a::writeVirtual(uint32_t value, uint32_t virtAddr, Value
 	if (!isMMUEnabled()) {
 		// direct virtual -> physical mapping, sans MMU
 		if (!writePhysical(value, virtAddr, valueSize))
-			return NonMMUError;
+			return encodeFault(NonMMUError, 0, virtAddr);
 	} else {
 		auto translated = translateAddressUsingTlb(virtAddr);
 		if (holds_alternative<MMUFault>(translated))
@@ -965,12 +984,61 @@ ARM710a::MMUFault ARM710a::checkAccessPermissions(ARM710a::TlbEntry *entry, uint
 void ARM710a::reportFault(MMUFault fault) {
 	if (fault != NoFault) {
 		if ((fault & 0xF) != NonMMUError) {
-			cp15_faultStatus = fault & 0xFFFF;
+			cp15_faultStatus = fault & (MMUFaultTypeMask | MMUFaultDomainMask);
-			cp15_faultAddress = fault >> 32;
+			cp15_faultAddress = fault >> MMUFaultAddressShift;
 		}
 
+		static const char *faultTypes[] = {
+			"NoFault",
+			"AlignmentFault",
+			"???",
+			"NonMMUError",
+			"SectionLinefetchError",
+			"SectionTranslationFault",
+			"PageLinefetchError",
+			"PageTranslationFault",
+			"SectionOtherBusError",
+			"SectionDomainFault",
+			"PageOtherBusError",
+			"PageDomainFault",
+			"Lv1TranslationError",
+			"SectionPermissionFault",
+			"Lv2TranslationError",
+			"PagePermissionFault"
+		};
+		log("⚠️ Fault type=%s domain=%d address=%08x pc=%08x lr=%08x",
+			faultTypes[fault & MMUFaultTypeMask],
+			(fault & MMUFaultDomainMask) >> MMUFaultDomainShift,
+			fault >> MMUFaultAddressShift,
+			GPRs[15], GPRs[14]);
+
 		// this signals a branch to DataAbort after the
 		// instruction is done executing
 		faultTriggeredThisCycle = true;
 	}
 }
+
+
+void ARM710a::log(const char *format, ...) {
+	if (logger) {
+		char buffer[1024];
+
+		va_list vaList;
+		va_start(vaList, format);
+		vsnprintf(buffer, sizeof(buffer), format, vaList);
+		va_end(vaList);
+
+		logger(buffer);
+	}
+}
+
+
+void ARM710a::test() {
+	uint64_t result;
+	uint32_t flags = 0;
+	uint32_t v = 0x10000000;
+
+	SUB_OP(v, v, 1);
+
+	log("RESULT:%llx FLAGS:%08x", result, flags);
+}

WindCore/arm710a.h

@@ -18,6 +18,8 @@ typedef optional<uint32_t> MaybeU32;
 class ARM710a
 {
 public:
+	void test();
+
 	enum ValueSize { V8 = 0, V32 = 1 };
 
 	enum MMUFault : uint64_t {
@@ -42,8 +44,11 @@ public:
 		// so we are reusing it for nefarious purposes
 		NonMMUError             = 3,
 
+		MMUFaultTypeMask        = 0xF,
 		MMUFaultDomainMask      = 0xF0,
-		MMUFaultAddressMask     = 0xFFFFFFFF00000000
+		MMUFaultDomainShift     = 4,
+		MMUFaultAddressMask     = 0xFFFFFFFF00000000,
+		MMUFaultAddressShift    = 32
 	};
 
 
@@ -83,6 +88,7 @@ public:
 	void requestIRQ(); // pull nIRQ low
 	void reset();      // pull nRESET low
 
+	bool instructionReady() const { return (prefetchCount == 2); }
 	uint32_t tick();   // run the chip for at least 1 clock cycle
 
 	MaybeU32 readVirtualDebug(uint32_t virtAddr, ValueSize valueSize);
@@ -94,8 +100,14 @@ public:
 	virtual bool writePhysical(uint32_t value, uint32_t physAddr, ARM710a::ValueSize valueSize) = 0;
 
 	uint32_t getGPR(int index) const { return GPRs[index]; }
+	uint32_t getCPSR() const { return CPSR; }
 
+	void setLogger(std::function<void(const char *)> newLogger) { logger = newLogger; }
+protected:
+	void log(const char *format, ...);
 private:
+	std::function<void(const char *)> logger;
+
 	enum { Nop = 0xE1A00000 };
 
 	enum Mode : uint8_t {
@@ -158,22 +170,22 @@ private:
 	bool flagN() const { return CPSR & CPSR_N; }
 	bool checkCondition(int cond) const {
 		switch (cond) {
-		case 0:   return flagZ();
+		/*EQ*/ case 0:   return flagZ();
-		case 1:   return !flagZ();
+		/*NE*/ case 1:   return !flagZ();
-		case 2:   return flagC();
+		/*CS*/ case 2:   return flagC();
-		case 3:   return !flagC();
+		/*CC*/ case 3:   return !flagC();
-		case 4:   return flagN();
+		/*MI*/ case 4:   return flagN();
-		case 5:   return !flagN();
+		/*PL*/ case 5:   return !flagN();
-		case 6:   return flagV();
+		/*VS*/ case 6:   return flagV();
-		case 7:   return !flagV();
+		/*VC*/ case 7:   return !flagV();
-		case 8:   return flagC() && !flagZ();
+		/*HI*/ case 8:   return flagC() && !flagZ();
-		case 9:   return !flagC() || flagZ();
+		/*LS*/ case 9:   return !flagC() || flagZ();
-		case 0xA: return flagN() == flagV();
+		/*GE*/ case 0xA: return flagN() == flagV();
-		case 0xB: return flagN() != flagV();
+		/*LT*/ case 0xB: return flagN() != flagV();
-		case 0xC: return !flagZ() && (flagN() == flagV());
+		/*GT*/ case 0xC: return !flagZ() && (flagN() == flagV());
-		case 0xD: return flagZ() || (flagN() != flagV());
+		/*LE*/ case 0xD: return flagZ() || (flagN() != flagV());
-		case 0xE: return true;
+		/*AL*/ case 0xE: return true;
-		/*case 0xF:*/
+		/*NV*/ /*case 0xF:*/
 		default:  return false;
 		}
 	}

WindCore/emu.cpp

@@ -224,6 +224,8 @@ MaybeU32 Emu::readPhysical(uint32_t physAddr, ValueSize valueSize) {
 		else if (region == 0xD1)
 			return MemoryBlockD1[physAddr & MemoryBlockMask];
 #endif
+		else if (region >= 0xC0)
+			return 0xFF; // just throw accesses to unmapped RAM away
 	} else {
 		uint32_t result;
 		if (region == 0)
@@ -244,6 +246,8 @@ MaybeU32 Emu::readPhysical(uint32_t physAddr, ValueSize valueSize) {
 		else if (region == 0xD1)
 			LOAD_32LE(result, physAddr & MemoryBlockMask, MemoryBlockD1);
 #endif
+		else if (region >= 0xC0)
+			return 0xFFFFFFFF; // just throw accesses to unmapped RAM away
 		else
 			return {};
 		return result;
@@ -267,6 +271,8 @@ bool Emu::writePhysical(uint32_t value, uint32_t physAddr, ValueSize valueSize)
 		else if (region == 0xD1)
 			MemoryBlockD1[physAddr & MemoryBlockMask] = (uint8_t)value;
 #endif
+		else if (region >= 0xC0)
+			return true; // just throw accesses to unmapped RAM away
 		else if (region == 0x20 && physAddr <= 0x20000FFF)
 			etna.writeReg8(physAddr & 0xFFF, value);
 		else if (region == 0x80 && physAddr <= 0x80000FFF)
@@ -287,6 +293,8 @@ bool Emu::writePhysical(uint32_t value, uint32_t physAddr, ValueSize valueSize)
 		else if (region == 0xD1)
 			STORE_32LE(value, physAddr & MemoryBlockMask, MemoryBlockD1);
 #endif
+		else if (region >= 0xC0)
+			return true; // just throw accesses to unmapped RAM away
 		else if (region == 0x20 && physAddr <= 0x20000FFF)
 			etna.writeReg32(physAddr & 0xFFF, value);
 		else if (region == 0x80 && physAddr <= 0x80000FFF)
@@ -311,6 +319,7 @@ void Emu::configure() {
 	nextTickAt = TICK_INTERVAL;
 	rtc = getRTC();
 
+	setProcessorID(0x41807100);
 	reset();
 }
 
@@ -352,11 +361,15 @@ void Emu::executeUntil(int64_t cycles) {
 			// keep the clock moving
 			passedCycles++;
 		} else {
+			if (auto v = virtToPhys(getGPR(15) - 0xC); v.has_value() && instructionReady())
+				debugPC(v.value());
 			passedCycles += tick();
 
 			uint32_t new_pc = getGPR(15) - 0xC;
-			if (_breakpoints.find(new_pc) != _breakpoints.end())
+			if (_breakpoints.find(new_pc) != _breakpoints.end()) {
+				log("⚠️ Breakpoint triggered at %08x!\n", new_pc);
 				return;
+			}
 		}
 	}
 }
@@ -426,14 +439,34 @@ void Emu::debugPC(uint32_t pc) {
 		const char *wut = identifyObjectCon(container);
 		if (wut) {
 			fetchName(obj, objName);
-			printf("OBJS: added %s at %08x <%s>", wut, obj, objName);
 			if (strcmp(wut, "process") == 0) {
-				fetchProcessFilename(obj, objName);
+				char procName[1000];
-				printf(" <%s>", objName);
+				fetchProcessFilename(obj, procName);
+				log("OBJS: added %s at %08x <%s> <%s>", wut, obj, objName, procName);
+			} else {
+				log("OBJS: added %s at %08x <%s>", wut, obj, objName);
 			}
-			printf("\n");
 		}
 	}
+
+	if (pc == 0x6D8) {
+		uint32_t virtAddr = getGPR(0);
+		uint32_t physAddr = getGPR(1);
+		uint32_t btIndex = getGPR(2);
+		uint32_t regionSize = getGPR(3);
+		log("KERNEL MMU SECTION: v:%08x p:%08x size:%08x idx:%02x",
+			virtAddr, physAddr, regionSize, btIndex);
+	}
+	if (pc == 0x710) {
+		uint32_t virtAddr = getGPR(0);
+		uint32_t physAddr = getGPR(1);
+		uint32_t btIndex = getGPR(2);
+		uint32_t regionSize = getGPR(3);
+		uint32_t pageTableA = getGPR(4);
+		uint32_t pageTableB = getGPR(5);
+		log("KERNEL MMU PAGES: v:%08x p:%08x size:%08x idx:%02x tableA:%08x tableB:%08x",
+			virtAddr, physAddr, regionSize, btIndex, pageTableA, pageTableB);
+	}
 }
 
 

WindQt/mainwindow.cpp

@@ -10,9 +10,14 @@ MainWindow::MainWindow(QWidget *parent) :
     ui(new Ui::MainWindow)
 {
     ui->setupUi(this);
+	ui->logView->setMaximumBlockCount(1000);
 
     emu = new Emu;
 	emu->loadROM("/Users/ash/src/psion/Sys$rom.bin");
+	emu->setLogger([&](const char *str) {
+		ui->logView->appendPlainText(str);
+	});
+	emu->test();
 
     timer = new QTimer(this);
     timer->setInterval(1000/64);
@@ -32,8 +37,25 @@ void MainWindow::updateScreen()
 
 	updateMemory();
 
+	char flagDisplay[] = {
+		(emu->getCPSR() & 0x80000000) ? 'N' : '-',
+		(emu->getCPSR() & 0x40000000) ? 'Z' : '-',
+		(emu->getCPSR() & 0x20000000) ? 'C' : '-',
+		(emu->getCPSR() & 0x10000000) ? 'V' : '-',
+		0
+	};
+	const char *modeName = "???";
+	switch (emu->getCPSR() & 0x1F) {
+	case 0x10: modeName = "User"; break;
+	case 0x11: modeName = "FIQ"; break;
+	case 0x12: modeName = "IRQ"; break;
+	case 0x13: modeName = "Supervisor"; break;
+	case 0x17: modeName = "Abort"; break;
+	case 0x1B: modeName = "Undefined"; break;
+	}
+
     ui->regsLabel->setText(
-				QString("R0: %1 / R1: %2 / R2: %3 / R3: %4 / R4: %5 / R5: %6 / R6: %7 / R7: %8\nR8: %9 / R9: %10 / R10:%11 / R11:%12 / R12:%13 / SP: %14 / LR: %15 / PC: %16")
+				QString("R0: %1 / R1: %2 / R2: %3 / R3: %4 / R4: %5 / R5: %6 / R6: %7 / R7: %8\nR8: %9 / R9: %10 / R10:%11 / R11:%12 / R12:%13 / SP: %14 / LR: %15 / PC: %16\n%17 / Mode: %18")
                 .arg(emu->getGPR(0), 8, 16)
                 .arg(emu->getGPR(1), 8, 16)
                 .arg(emu->getGPR(2), 8, 16)
@@ -50,11 +72,13 @@ void MainWindow::updateScreen()
                 .arg(emu->getGPR(13), 8, 16)
                 .arg(emu->getGPR(14), 8, 16)
                 .arg(emu->getGPR(15), 8, 16)
+				.arg(flagDisplay)
+				.arg(modeName)
                 );
 
     // show a crude disassembly
     const int context = 8 * 4;
-    uint32_t pc = emu->getGPR(15) - 4;
+	uint32_t pc = emu->getGPR(15) - 8;
     uint32_t minCode = pc - context;
 	if (minCode >= (UINT32_MAX - context))
         minCode = 0;
@@ -64,7 +88,7 @@ void MainWindow::updateScreen()
 
 	QStringList codeLines;
 	for (uint32_t addr = minCode; addr >= minCode && addr <= maxCode; addr += 4) {
-		const char *prefix = (addr == pc) ? "==>" : "   ";
+		const char *prefix = (addr == pc) ? (emu->instructionReady() ? "==>" : "...") : "   ";
         struct ARMInstructionInfo info;
         char buffer[512];
 
@@ -228,8 +252,9 @@ void MainWindow::on_stopButton_clicked()
 
 void MainWindow::on_stepTickButton_clicked()
 {
-    emu->executeUntil(emu->currentCycles() + (CLOCK_SPEED * 2));
+//    emu->executeUntil(emu->currentCycles() + (CLOCK_SPEED * 2));
-    updateScreen();
+	emu->executeUntil(emu->currentCycles() + 25000);
+	updateScreen();
 }
 
 void MainWindow::on_stepInsnButton_clicked()

WindQt/mainwindow.ui

@@ -22,72 +22,6 @@
       </property>
      </widget>
     </item>
-    <item row="3" column="0" colspan="5">
-     <widget class="QLabel" name="regsLabel">
-      <property name="font">
-       <font>
-        <family>Courier New</family>
-       </font>
-      </property>
-      <property name="text">
-       <string/>
-      </property>
-     </widget>
-    </item>
-    <item row="1" column="3">
-     <widget class="QPushButton" name="startButton">
-      <property name="text">
-       <string>Start</string>
-      </property>
-     </widget>
-    </item>
-    <item row="2" column="4">
-     <widget class="QPushButton" name="stepTickButton">
-      <property name="text">
-       <string>Step (Tick)</string>
-      </property>
-     </widget>
-    </item>
-    <item row="0" column="0" colspan="6">
-     <widget class="QLabel" name="screen">
-      <property name="focusPolicy">
-       <enum>Qt::ClickFocus</enum>
-      </property>
-      <property name="text">
-       <string/>
-      </property>
-     </widget>
-    </item>
-    <item row="2" column="3">
-     <widget class="QPushButton" name="stepInsnButton">
-      <property name="text">
-       <string>Step (Insn)</string>
-      </property>
-     </widget>
-    </item>
-    <item row="1" column="2">
-     <spacer name="horizontalSpacer">
-      <property name="orientation">
-       <enum>Qt::Horizontal</enum>
-      </property>
-      <property name="sizeHint" stdset="0">
-       <size>
-        <width>40</width>
-        <height>20</height>
-       </size>
-      </property>
-     </spacer>
-    </item>
-    <item row="1" column="4">
-     <widget class="QPushButton" name="stopButton">
-      <property name="enabled">
-       <bool>false</bool>
-      </property>
-      <property name="text">
-       <string>Stop</string>
-      </property>
-     </widget>
-    </item>
     <item row="4" column="0" colspan="5">
      <widget class="QTabWidget" name="tabWidget">
       <property name="currentIndex">
@@ -315,6 +249,75 @@
       </widget>
      </widget>
     </item>
+    <item row="3" column="0" colspan="5">
+     <widget class="QLabel" name="regsLabel">
+      <property name="font">
+       <font>
+        <family>Courier New</family>
+       </font>
+      </property>
+      <property name="text">
+       <string/>
+      </property>
+     </widget>
+    </item>
+    <item row="1" column="3">
+     <widget class="QPushButton" name="startButton">
+      <property name="text">
+       <string>Start</string>
+      </property>
+     </widget>
+    </item>
+    <item row="2" column="4">
+     <widget class="QPushButton" name="stepTickButton">
+      <property name="text">
+       <string>Step (Tick)</string>
+      </property>
+     </widget>
+    </item>
+    <item row="0" column="0" colspan="6">
+     <widget class="QLabel" name="screen">
+      <property name="focusPolicy">
+       <enum>Qt::ClickFocus</enum>
+      </property>
+      <property name="text">
+       <string/>
+      </property>
+     </widget>
+    </item>
+    <item row="2" column="3">
+     <widget class="QPushButton" name="stepInsnButton">
+      <property name="text">
+       <string>Step (Insn)</string>
+      </property>
+     </widget>
+    </item>
+    <item row="1" column="2">
+     <spacer name="horizontalSpacer">
+      <property name="orientation">
+       <enum>Qt::Horizontal</enum>
+      </property>
+      <property name="sizeHint" stdset="0">
+       <size>
+        <width>40</width>
+        <height>20</height>
+       </size>
+      </property>
+     </spacer>
+    </item>
+    <item row="1" column="4">
+     <widget class="QPushButton" name="stopButton">
+      <property name="enabled">
+       <bool>false</bool>
+      </property>
+      <property name="text">
+       <string>Stop</string>
+      </property>
+     </widget>
+    </item>
+    <item row="5" column="0" colspan="5">
+     <widget class="QPlainTextEdit" name="logView"/>
+    </item>
    </layout>
   </widget>
  </widget>