@@ -84,6 +84,9 @@ void (*setWatchpoint)(struct mDebuggerPlatform*, uint32_t address, int segment, enum mWatchpointType type);
 	void (*clearWatchpoint)(struct mDebuggerPlatform*, uint32_t address, int segment);
 	void (*checkBreakpoints)(struct mDebuggerPlatform*);
 	void (*trace)(struct mDebuggerPlatform*, char* out, size_t* length);
+
+	bool (*getRegister)(struct mDebuggerPlatform*, const char* name, int32_t* value);
+	bool (*setRegister)(struct mDebuggerPlatform*, const char* name, int32_t value);
 };
 
 struct mDebuggerSymbols;

@@ -14,6 +14,7 @@ #include <mgba/debugger/debugger.h>
 
 extern const char* ERROR_MISSING_ARGS;
 extern const char* ERROR_OVERFLOW;
+extern const char* ERROR_INVALID_ARGS;
 
 struct CLIDebugger;
 
@@ -51,7 +52,6 @@ bool (*custom)(struct CLIDebuggerSystem*);
 
 	void (*disassemble)(struct CLIDebuggerSystem*, struct CLIDebugVector* dv);
 	uint32_t (*lookupIdentifier)(struct CLIDebuggerSystem*, const char* name, struct CLIDebugVector* dv);
-	uint32_t (*lookupPlatformIdentifier)(struct CLIDebuggerSystem*, const char* name, struct CLIDebugVector* dv);
 	void (*printStatus)(struct CLIDebuggerSystem*);
 
 	struct CLIDebuggerCommandSummary* commands;

@@ -17,7 +17,6 @@ static void _disassembleArm(struct CLIDebugger*, struct CLIDebugVector*);
 static void _disassembleThumb(struct CLIDebugger*, struct CLIDebugVector*);
 static void _setBreakpointARM(struct CLIDebugger*, struct CLIDebugVector*);
 static void _setBreakpointThumb(struct CLIDebugger*, struct CLIDebugVector*);
-static void _writeRegister(struct CLIDebugger*, struct CLIDebugVector*);
 
 static void _disassembleMode(struct CLIDebugger*, struct CLIDebugVector*, enum ExecutionMode mode);
 static uint32_t _printLine(struct CLIDebugger* debugger, uint32_t address, enum ExecutionMode mode);
@@ -33,7 +32,6 @@ { "disasm/a", _disassembleArm, "Ii", "Disassemble instructions as ARM" },
 	{ "disasm/t", _disassembleThumb, "Ii", "Disassemble instructions as Thumb" },
 	{ "disassemble/a", _disassembleArm, "Ii", "Disassemble instructions as ARM" },
 	{ "disassemble/t", _disassembleThumb, "Ii", "Disassemble instructions as Thumb" },
-	{ "w/r", _writeRegister, "SI", "Write a register" },
 	{ 0, 0, 0, 0 }
 };
 
@@ -145,31 +143,6 @@ }
 	_printLine(debugger->p, cpu->gprs[ARM_PC] - instructionLength, mode);
 }
 
-static void _writeRegister(struct CLIDebugger* debugger, struct CLIDebugVector* dv) {
-	struct CLIDebuggerBackend* be = debugger->backend;
-	struct ARMCore* cpu = debugger->d.core->cpu;
-	if (!dv || dv->type != CLIDV_CHAR_TYPE) {
-		be->printf(be, "%s\n", ERROR_MISSING_ARGS);
-		return;
-	}
-	if (!dv->next || dv->next->type != CLIDV_INT_TYPE) {
-		be->printf(be, "%s\n", ERROR_MISSING_ARGS);
-		return;
-	}
-	char* end;
-	uint32_t regid = strtoul(&dv->charValue[1], &end, 10);
-	if (dv->charValue[0] != 'r' || (*end && !isspace(*end)) || regid > ARM_PC) {
-		be->printf(be, "%s\n", "Unknown register name");
-		return;
-	}
-	if (regid == ARM_PC) {
-		be->printf(be, "%s\n", "Cannot write to program counter");
-		return;
-	}
-	uint32_t value = dv->next->intValue;
-	cpu->gprs[regid] = value;
-}
-
 static void _setBreakpointARM(struct CLIDebugger* debugger, struct CLIDebugVector* dv) {
 	struct CLIDebuggerBackend* be = debugger->backend;
 	if (!dv || dv->type != CLIDV_INT_TYPE) {
@@ -190,38 +163,9 @@ uint32_t address = dv->intValue;
 	ARMDebuggerSetSoftwareBreakpoint(debugger->d.platform, address, MODE_THUMB);
 }
 
-static uint32_t _lookupPlatformIdentifier(struct CLIDebuggerSystem* debugger, const char* name, struct CLIDebugVector* dv) {
-	struct ARMCore* cpu = debugger->p->d.core->cpu;
-	if (strcmp(name, "sp") == 0) {
-		return cpu->gprs[ARM_SP];
-	}
-	if (strcmp(name, "lr") == 0) {
-		return cpu->gprs[ARM_LR];
-	}
-	if (strcmp(name, "pc") == 0) {
-		return cpu->gprs[ARM_PC];
-	}
-	if (strcmp(name, "cpsr") == 0) {
-		return cpu->cpsr.packed;
-	}
-	// TODO: test if mode has SPSR
-	if (strcmp(name, "spsr") == 0) {
-		return cpu->spsr.packed;
-	}
-	if (name[0] == 'r' && name[1] >= '0' && name[1] <= '9') {
-		int reg = atoi(&name[1]);
-		if (reg < 16) {
-			return cpu->gprs[reg];
-		}
-	}
-	dv->type = CLIDV_ERROR_TYPE;
-	return 0;
-}
-
 void ARMCLIDebuggerCreate(struct CLIDebuggerSystem* debugger) {
 	debugger->printStatus = _printStatus;
 	debugger->disassemble = _disassemble;
-	debugger->lookupPlatformIdentifier = _lookupPlatformIdentifier;
 	debugger->platformName = "ARM";
 	debugger->platformCommands = _armCommands;
 }

@@ -56,6 +56,8 @@ static void ARMDebuggerClearWatchpoint(struct mDebuggerPlatform*, uint32_t address, int segment);
 static void ARMDebuggerCheckBreakpoints(struct mDebuggerPlatform*);
 static bool ARMDebuggerHasBreakpoints(struct mDebuggerPlatform*);
 static void ARMDebuggerTrace(struct mDebuggerPlatform*, char* out, size_t* length);
+static bool ARMDebuggerGetRegister(struct mDebuggerPlatform*, const char* name, int32_t* value);
+static bool ARMDebuggerSetRegister(struct mDebuggerPlatform*, const char* name, int32_t value);
 
 struct mDebuggerPlatform* ARMDebuggerPlatformCreate(void) {
 	struct mDebuggerPlatform* platform = (struct mDebuggerPlatform*) malloc(sizeof(struct ARMDebugger));
@@ -69,6 +71,8 @@ platform->clearWatchpoint = ARMDebuggerClearWatchpoint;
 	platform->checkBreakpoints = ARMDebuggerCheckBreakpoints;
 	platform->hasBreakpoints = ARMDebuggerHasBreakpoints;
 	platform->trace = ARMDebuggerTrace;
+	platform->getRegister = ARMDebuggerGetRegister;
+	platform->setRegister = ARMDebuggerSetRegister;
 	return platform;
 }
 
@@ -246,3 +250,81 @@ cpu->gprs[8],  cpu->gprs[9],  cpu->gprs[10], cpu->gprs[11],
 		               cpu->gprs[12], cpu->gprs[13], cpu->gprs[14], cpu->gprs[15],
 		               cpu->cpsr.packed, disassembly);
 }
+
+bool ARMDebuggerGetRegister(struct mDebuggerPlatform* d, const char* name, int32_t* value) {
+	struct ARMDebugger* debugger = (struct ARMDebugger*) d;
+	struct ARMCore* cpu = debugger->cpu;
+
+	if (strcmp(name, "sp") == 0) {
+		*value = cpu->gprs[ARM_SP];
+		return true;
+	}
+	if (strcmp(name, "lr") == 0) {
+		*value = cpu->gprs[ARM_LR];
+		return true;
+	}
+	if (strcmp(name, "pc") == 0) {
+		*value = cpu->gprs[ARM_PC];
+		return true;
+	}
+	if (strcmp(name, "cpsr") == 0) {
+		*value = cpu->cpsr.packed;
+		return true;
+	}
+	// TODO: test if mode has SPSR
+	if (strcmp(name, "spsr") == 0) {
+		*value = cpu->spsr.packed;
+		return true;
+	}
+	if (name[0] == 'r') {
+		char* end;
+		uint32_t reg = strtoul(&name[1], &end, 10);
+		if (reg <= ARM_PC) {
+			*value = cpu->gprs[reg];
+			return true;
+		}
+	}
+	return false;
+}
+
+bool ARMDebuggerSetRegister(struct mDebuggerPlatform* d, const char* name, int32_t value) {
+	struct ARMDebugger* debugger = (struct ARMDebugger*) d;
+	struct ARMCore* cpu = debugger->cpu;
+
+	if (strcmp(name, "sp") == 0) {
+		cpu->gprs[ARM_SP] = value;
+		return true;
+	}
+	if (strcmp(name, "lr") == 0) {
+		cpu->gprs[ARM_LR] = value;
+		return true;
+	}
+	if (strcmp(name, "pc") == 0) {
+		cpu->gprs[ARM_PC] = value;
+		int32_t currentCycles = 0;
+		if (cpu->executionMode == MODE_ARM) {
+			ARM_WRITE_PC;
+		} else {
+			THUMB_WRITE_PC;
+		}
+		return true;
+	}
+	if (name[0] == 'r') {
+		char* end;
+		uint32_t reg = strtoul(&name[1], &end, 10);
+		if (reg > ARM_PC) {
+			return false;
+		}
+		cpu->gprs[reg] = value;
+		if (reg == ARM_PC) {
+			int32_t currentCycles = 0;
+			if (cpu->executionMode == MODE_ARM) {
+				ARM_WRITE_PC;
+			} else {
+				THUMB_WRITE_PC;
+			}
+		}
+		return true;
+	}
+	return false;
+}

@@ -26,6 +26,7 @@ #endif
 
 const char* ERROR_MISSING_ARGS = "Arguments missing"; // TODO: share
 const char* ERROR_OVERFLOW = "Arguments overflow";
+const char* ERROR_INVALID_ARGS = "Invalid arguments";
 
 #if !defined(NDEBUG) && !defined(_WIN32)
 static void _breakInto(struct CLIDebugger*, struct CLIDebugVector*);
@@ -51,6 +52,7 @@ static void _setWriteWatchpoint(struct CLIDebugger*, struct CLIDebugVector*);
 static void _trace(struct CLIDebugger*, struct CLIDebugVector*);
 static void _writeByte(struct CLIDebugger*, struct CLIDebugVector*);
 static void _writeHalfword(struct CLIDebugger*, struct CLIDebugVector*);
+static void _writeRegister(struct CLIDebugger*, struct CLIDebugVector*);
 static void _writeWord(struct CLIDebugger*, struct CLIDebugVector*);
 static void _dumpByte(struct CLIDebugger*, struct CLIDebugVector*);
 static void _dumpHalfword(struct CLIDebugger*, struct CLIDebugVector*);
@@ -92,6 +94,7 @@ { "trace", _trace, "I", "Trace a fixed number of instructions" },
 	{ "w", _setWatchpoint, "I", "Set a watchpoint" },
 	{ "w/1", _writeByte, "II", "Write a byte at a specified offset" },
 	{ "w/2", _writeHalfword, "II", "Write a halfword at a specified offset" },
+	{ "w/r", _writeRegister, "SI", "Write a register" },
 	{ "w/4", _writeWord, "II", "Write a word at a specified offset" },
 	{ "watch", _setWatchpoint, "I", "Set a watchpoint" },
 	{ "watch/r", _setReadWatchpoint, "I", "Set a read watchpoint" },
@@ -273,12 +276,12 @@ debugger->backend->printf(debugger->backend, " 0x%08X\n", value);
 }
 
 static void _writeByte(struct CLIDebugger* debugger, struct CLIDebugVector* dv) {
-	if (!dv || dv->type != CLIDV_INT_TYPE) {
+	if (!dv || !dv->next) {
 		debugger->backend->printf(debugger->backend, "%s\n", ERROR_MISSING_ARGS);
 		return;
 	}
-	if (!dv->next || dv->next->type != CLIDV_INT_TYPE) {
-		debugger->backend->printf(debugger->backend, "%s\n", ERROR_MISSING_ARGS);
+	if (dv->type != CLIDV_INT_TYPE || dv->next->type != CLIDV_INT_TYPE) {
+		debugger->backend->printf(debugger->backend, "%s\n", ERROR_INVALID_ARGS);
 		return;
 	}
 	uint32_t address = dv->intValue;
@@ -295,12 +298,12 @@ }
 }
 
 static void _writeHalfword(struct CLIDebugger* debugger, struct CLIDebugVector* dv) {
-	if (!dv || dv->type != CLIDV_INT_TYPE) {
+	if (!dv || !dv->next) {
 		debugger->backend->printf(debugger->backend, "%s\n", ERROR_MISSING_ARGS);
 		return;
 	}
-	if (!dv->next || dv->next->type != CLIDV_INT_TYPE) {
-		debugger->backend->printf(debugger->backend, "%s\n", ERROR_MISSING_ARGS);
+	if (dv->type != CLIDV_INT_TYPE || dv->next->type != CLIDV_INT_TYPE) {
+		debugger->backend->printf(debugger->backend, "%s\n", ERROR_INVALID_ARGS);
 		return;
 	}
 	uint32_t address = dv->intValue;
@@ -316,13 +319,27 @@ debugger->d.core->busWrite16(debugger->d.core, address, value);
 	}
 }
 
+static void _writeRegister(struct CLIDebugger* debugger, struct CLIDebugVector* dv) {
+	if (!dv || !dv->next) {
+		debugger->backend->printf(debugger->backend, "%s\n", ERROR_MISSING_ARGS);
+		return;
+	}
+	if (dv->type != CLIDV_CHAR_TYPE || dv->next->type != CLIDV_INT_TYPE) {
+		debugger->backend->printf(debugger->backend, "%s\n", ERROR_INVALID_ARGS);
+		return;
+	}
+	if (!debugger->d.platform->setRegister(debugger->d.platform, dv->charValue, dv->next->intValue)) {
+		debugger->backend->printf(debugger->backend, "%s\n", ERROR_INVALID_ARGS);
+	}
+}
+
 static void _writeWord(struct CLIDebugger* debugger, struct CLIDebugVector* dv) {
-	if (!dv || dv->type != CLIDV_INT_TYPE) {
+	if (!dv || !dv->next) {
 		debugger->backend->printf(debugger->backend, "%s\n", ERROR_MISSING_ARGS);
 		return;
 	}
-	if (!dv->next || dv->next->type != CLIDV_INT_TYPE) {
-		debugger->backend->printf(debugger->backend, "%s\n", ERROR_MISSING_ARGS);
+	if (dv->type != CLIDV_INT_TYPE || dv->next->type != CLIDV_INT_TYPE) {
+		debugger->backend->printf(debugger->backend, "%s\n", ERROR_INVALID_ARGS);
 		return;
 	}
 	uint32_t address = dv->intValue;
@@ -559,12 +576,10 @@ #endif
 		if (debugger->core->symbolTable && mDebuggerSymbolLookup(debugger->core->symbolTable, name, &dv->intValue, &dv->segmentValue)) {
 			return;
 		}
-		value = cliDebugger->system->lookupPlatformIdentifier(cliDebugger->system, name, dv);
-		if (dv->type != CLIDV_ERROR_TYPE) {
-			dv->intValue = value;
+		dv->type = CLIDV_INT_TYPE;
+		if (debugger->platform->getRegister(debugger->platform, name, &dv->intValue)) {
 			return;
 		}
-		dv->type = CLIDV_INT_TYPE;
 		value = cliDebugger->system->lookupIdentifier(cliDebugger->system, name, dv);
 		if (dv->type != CLIDV_ERROR_TYPE) {
 			dv->intValue = value;

@@ -100,58 +100,9 @@ _printFlags(be, cpu->f);
 	_printLine(debugger->p, cpu->pc, cpu->memory.currentSegment(cpu, cpu->pc));
 }
 
-static uint32_t _lookupPlatformIdentifier(struct CLIDebuggerSystem* debugger, const char* name, struct CLIDebugVector* dv) {
-	struct LR35902Core* cpu = debugger->p->d.core->cpu;
-	if (strcmp(name, "a") == 0) {
-		return cpu->a;
-	}
-	if (strcmp(name, "b") == 0) {
-		return cpu->b;
-	}
-	if (strcmp(name, "c") == 0) {
-		return cpu->c;
-	}
-	if (strcmp(name, "d") == 0) {
-		return cpu->d;
-	}
-	if (strcmp(name, "e") == 0) {
-		return cpu->e;
-	}
-	if (strcmp(name, "h") == 0) {
-		return cpu->h;
-	}
-	if (strcmp(name, "l") == 0) {
-		return cpu->l;
-	}
-	if (strcmp(name, "bc") == 0) {
-		return cpu->bc;
-	}
-	if (strcmp(name, "de") == 0) {
-		return cpu->de;
-	}
-	if (strcmp(name, "hl") == 0) {
-		return cpu->hl;
-	}
-	if (strcmp(name, "af") == 0) {
-		return cpu->af;
-	}
-	if (strcmp(name, "pc") == 0) {
-		return cpu->pc;
-	}
-	if (strcmp(name, "sp") == 0) {
-		return cpu->sp;
-	}
-	if (strcmp(name, "f") == 0) {
-		return cpu->f.packed;
-	}
-	dv->type = CLIDV_ERROR_TYPE;
-	return 0;
-}
-
 void LR35902CLIDebuggerCreate(struct CLIDebuggerSystem* debugger) {
 	debugger->printStatus = _printStatus;
 	debugger->disassemble = _disassemble;
-	debugger->lookupPlatformIdentifier = _lookupPlatformIdentifier;
 	debugger->platformName = "GB-Z80";
 	debugger->platformCommands = _lr35902Commands;
 }

@@ -50,6 +50,8 @@ static void LR35902DebuggerClearWatchpoint(struct mDebuggerPlatform*, uint32_t address, int segment);
 static void LR35902DebuggerCheckBreakpoints(struct mDebuggerPlatform*);
 static bool LR35902DebuggerHasBreakpoints(struct mDebuggerPlatform*);
 static void LR35902DebuggerTrace(struct mDebuggerPlatform*, char* out, size_t* length);
+static bool LR35902DebuggerGetRegister(struct mDebuggerPlatform*, const char* name, int32_t* value);
+static bool LR35902DebuggerSetRegister(struct mDebuggerPlatform*, const char* name, int32_t value);
 
 struct mDebuggerPlatform* LR35902DebuggerPlatformCreate(void) {
 	struct mDebuggerPlatform* platform = (struct mDebuggerPlatform*) malloc(sizeof(struct LR35902Debugger));
@@ -63,6 +65,8 @@ platform->clearWatchpoint = LR35902DebuggerClearWatchpoint;
 	platform->checkBreakpoints = LR35902DebuggerCheckBreakpoints;
 	platform->hasBreakpoints = LR35902DebuggerHasBreakpoints;
 	platform->trace = LR35902DebuggerTrace;
+	platform->getRegister = LR35902DebuggerGetRegister;
+	platform->setRegister = LR35902DebuggerSetRegister;
 	return platform;
 }
 
@@ -168,3 +172,131 @@ cpu->a, cpu->f.packed, cpu->b, cpu->c,
 		               cpu->d, cpu->e, cpu->h, cpu->l,
 		               cpu->sp, cpu->pc, disassembly);
 }
+
+bool LR35902DebuggerGetRegister(struct mDebuggerPlatform* d, const char* name, int32_t* value) {
+	struct LR35902Debugger* debugger = (struct LR35902Debugger*) d;
+	struct LR35902Core* cpu = debugger->cpu;
+
+	if (strcmp(name, "a") == 0) {
+		*value = cpu->a;
+		return true;
+	}
+	if (strcmp(name, "b") == 0) {
+		*value = cpu->b;
+		return true;
+	}
+	if (strcmp(name, "c") == 0) {
+		*value = cpu->c;
+		return true;
+	}
+	if (strcmp(name, "d") == 0) {
+		*value = cpu->d;
+		return true;
+	}
+	if (strcmp(name, "e") == 0) {
+		*value = cpu->e;
+		return true;
+	}
+	if (strcmp(name, "h") == 0) {
+		*value = cpu->h;
+		return true;
+	}
+	if (strcmp(name, "l") == 0) {
+		*value = cpu->l;
+		return true;
+	}
+	if (strcmp(name, "bc") == 0) {
+		*value = cpu->bc;
+		return true;
+	}
+	if (strcmp(name, "de") == 0) {
+		*value = cpu->de;
+		return true;
+	}
+	if (strcmp(name, "hl") == 0) {
+		*value = cpu->hl;
+		return true;
+	}
+	if (strcmp(name, "af") == 0) {
+		*value = cpu->af;
+		return true;
+	}
+	if (strcmp(name, "pc") == 0) {
+		*value = cpu->pc;
+		return true;
+	}
+	if (strcmp(name, "sp") == 0) {
+		*value = cpu->sp;
+		return true;
+	}
+	if (strcmp(name, "f") == 0) {
+		*value = cpu->f.packed;
+		return true;
+	}
+	return false;
+}
+
+bool LR35902DebuggerSetRegister(struct mDebuggerPlatform* d, const char* name, int32_t value) {
+	struct LR35902Debugger* debugger = (struct LR35902Debugger*) d;
+	struct LR35902Core* cpu = debugger->cpu;
+
+	if (strcmp(name, "a") == 0) {
+		cpu->a = value;
+		return true;
+	}
+	if (strcmp(name, "b") == 0) {
+		cpu->b = value;
+		return true;
+	}
+	if (strcmp(name, "c") == 0) {
+		cpu->c = value;
+		return true;
+	}
+	if (strcmp(name, "d") == 0) {
+		cpu->d = value;
+		return true;
+	}
+	if (strcmp(name, "e") == 0) {
+		cpu->e = value;
+		return true;
+	}
+	if (strcmp(name, "h") == 0) {
+		cpu->h = value;
+		return true;
+	}
+	if (strcmp(name, "l") == 0) {
+		cpu->l = value;
+		return true;
+	}
+	if (strcmp(name, "bc") == 0) {
+		cpu->bc = value;
+		return true;
+	}
+	if (strcmp(name, "de") == 0) {
+		cpu->de = value;
+		return true;
+	}
+	if (strcmp(name, "hl") == 0) {
+		cpu->hl = value;
+		return true;
+	}
+	if (strcmp(name, "af") == 0) {
+		cpu->af = value;
+		cpu->f.packed &= 0xF0;
+		return true;
+	}
+	if (strcmp(name, "pc") == 0) {
+		cpu->pc = value;
+		cpu->memory.setActiveRegion(cpu, cpu->pc);
+		return true;
+	}
+	if (strcmp(name, "sp") == 0) {
+		cpu->sp = value;
+		return true;
+	}
+	if (strcmp(name, "f") == 0) {
+		cpu->f.packed = value & 0xF0;
+		return true;
+	}
+	return false;
+}