@@ -85,6 +85,8 @@
 struct ARMBoard {
 	struct ARMCore* cpu;
 	void (*reset)(struct ARMBoard* board);
+
+	void (*hitStub)(struct ARMBoard* board, uint32_t opcode);
 };
 
 struct ARMCore {

@@ -1,11 +1,14 @@
 #include "gba.h"
 
+#include <stdarg.h>
+#include <stdio.h>
 #include <sys/mman.h>
 #include <unistd.h>
 
 static const char* GBA_CANNOT_MMAP = "Could not map memory";
 
 static void GBASetActiveRegion(struct ARMMemory* memory, uint32_t region);
+static void GBAHitStub(struct ARMBoard* board, uint32_t opcode);
 
 void GBAInit(struct GBA* gba) {
 	gba->errno = GBA_NO_ERROR;
@@ -60,6 +63,7 @@ }
 
 void GBABoardInit(struct GBABoard* board) {
 	board->d.reset = GBABoardReset;
+	board->d.hitStub = GBAHitStub;
 }
 
 void GBABoardReset(struct ARMBoard* board) {
@@ -367,3 +371,15 @@ default:
 		break;
 	}
 }
+
+void GBALog(int level, const char* format, ...) {
+	va_list args;
+	va_start(args, format);
+	vprintf(format, args);
+	va_end(args);
+	printf("\n");
+}
+
+void GBAHitStub(struct ARMBoard* board, uint32_t opcode) {
+	GBALog(GBA_LOG_STUB, "Stub opcode: %08x", opcode);
+}

@@ -8,6 +8,10 @@ GBA_NO_ERROR = 0,
 	GBA_OUT_OF_MEMORY = -1
 };
 
+enum GBALogLevel {
+	GBA_LOG_STUB
+};
+
 enum GBAMemoryRegion {
 	REGION_BIOS = 0x0,
 	REGION_WORKING_RAM = 0x2,

@@ -345,18 +345,18 @@ // End ALU definitions
 
 // Begin multiply definitions
 
-DEFINE_INSTRUCTION_ARM(MLA,)
-DEFINE_INSTRUCTION_ARM(MLAS,)
-DEFINE_INSTRUCTION_ARM(MUL,)
-DEFINE_INSTRUCTION_ARM(MULS,)
-DEFINE_INSTRUCTION_ARM(SMLAL,)
-DEFINE_INSTRUCTION_ARM(SMLALS,)
-DEFINE_INSTRUCTION_ARM(SMULL,)
-DEFINE_INSTRUCTION_ARM(SMULLS,)
-DEFINE_INSTRUCTION_ARM(UMLAL,)
-DEFINE_INSTRUCTION_ARM(UMLALS,)
-DEFINE_INSTRUCTION_ARM(UMULL,)
-DEFINE_INSTRUCTION_ARM(UMULLS,)
+DEFINE_INSTRUCTION_ARM(MLA, ARM_STUB)
+DEFINE_INSTRUCTION_ARM(MLAS, ARM_STUB)
+DEFINE_INSTRUCTION_ARM(MUL, ARM_STUB)
+DEFINE_INSTRUCTION_ARM(MULS, ARM_STUB)
+DEFINE_INSTRUCTION_ARM(SMLAL, ARM_STUB)
+DEFINE_INSTRUCTION_ARM(SMLALS, ARM_STUB)
+DEFINE_INSTRUCTION_ARM(SMULL, ARM_STUB)
+DEFINE_INSTRUCTION_ARM(SMULLS, ARM_STUB)
+DEFINE_INSTRUCTION_ARM(UMLAL, ARM_STUB)
+DEFINE_INSTRUCTION_ARM(UMLALS, ARM_STUB)
+DEFINE_INSTRUCTION_ARM(UMULL, ARM_STUB)
+DEFINE_INSTRUCTION_ARM(UMULLS, ARM_STUB)
 
 // End multiply definitions
 
@@ -395,11 +395,11 @@ ARMSetPrivilegeMode(cpu, MODE_USER); \
 	cpu->memory->store8(cpu->memory, address, cpu->gprs[rd]); \
 	ARMSetPrivilegeMode(cpu, priv);)
 
-DEFINE_LOAD_STORE_MULTIPLE_INSTRUCTION_ARM(LDM,)
-DEFINE_LOAD_STORE_MULTIPLE_INSTRUCTION_ARM(STM,)
+DEFINE_LOAD_STORE_MULTIPLE_INSTRUCTION_ARM(LDM, ARM_STUB)
+DEFINE_LOAD_STORE_MULTIPLE_INSTRUCTION_ARM(STM, ARM_STUB)
 
-DEFINE_INSTRUCTION_ARM(SWP,)
-DEFINE_INSTRUCTION_ARM(SWPB,)
+DEFINE_INSTRUCTION_ARM(SWP, ARM_STUB)
+DEFINE_INSTRUCTION_ARM(SWPB, ARM_STUB)
 
 // End load/store definitions
 
@@ -411,14 +411,15 @@ offset >>= 6; \
 	cpu->gprs[ARM_PC] += offset; \
 	ARM_WRITE_PC;)
 
-DEFINE_INSTRUCTION_ARM(BL,)
-DEFINE_INSTRUCTION_ARM(BX,)
+DEFINE_INSTRUCTION_ARM(BL, ARM_STUB)
+DEFINE_INSTRUCTION_ARM(BX, ARM_STUB)
 
 // End branch definitions
 
-// TODO
-DEFINE_INSTRUCTION_ARM(BKPT,)
-DEFINE_INSTRUCTION_ARM(ILL,) // Illegal opcode
+// Begin miscellaneous definitions
+
+DEFINE_INSTRUCTION_ARM(BKPT, ARM_STUB) // Not strictly in ARMv4T, but here for convenience
+DEFINE_INSTRUCTION_ARM(ILL, ARM_STUB) // Illegal opcode
 
 DEFINE_INSTRUCTION_ARM(MSR, \
 	int c = opcode & 0x00010000; \
@@ -449,10 +450,10 @@ cpu->cpsr.f = operand & 0x00000040; \
 		} \
 	})
 
-DEFINE_INSTRUCTION_ARM(MRS,)
-DEFINE_INSTRUCTION_ARM(MSRI,)
-DEFINE_INSTRUCTION_ARM(MRSI,)
-DEFINE_INSTRUCTION_ARM(SWI,)
+DEFINE_INSTRUCTION_ARM(MRS, ARM_STUB)
+DEFINE_INSTRUCTION_ARM(MSRI, ARM_STUB)
+DEFINE_INSTRUCTION_ARM(MRSI, ARM_STUB)
+DEFINE_INSTRUCTION_ARM(SWI, ARM_STUB)
 
 #define DECLARE_INSTRUCTION_ARM(EMITTER, NAME) \
 	EMITTER ## NAME

@@ -52,6 +52,8 @@ #define ARM_BORROW_FROM(M, N, D) (((uint32_t) (M)) >= ((uint32_t) (N)))
 #define ARM_V_ADDITION(M, N, D) (!(ARM_SIGN((M) ^ (N))) && (ARM_SIGN((M) ^ (D))) && (ARM_SIGN((N) ^ (D))))
 #define ARM_V_SUBTRACTION(M, N, D) ((ARM_SIGN((M) ^ (N))) && (ARM_SIGN((M) ^ (D))))
 
+#define ARM_STUB cpu->board->hitStub(cpu->board, opcode)
+
 static inline int _ARMModeHasSPSR(enum PrivilegeMode mode) {
 	return mode != MODE_SYSTEM && mode != MODE_USER;
 }