@@ -4,6 +4,8 @@ #include "isa-arm.h"
 #include "isa-inlines.h"
 #include "isa-thumb.h"
 
+#include <limits.h>
+
 static inline enum RegisterBank _ARMSelectBank(enum PrivilegeMode);
 
 void ARMSetPrivilegeMode(struct ARMCore* cpu, enum PrivilegeMode mode) {
@@ -97,7 +99,8 @@
 	cpu->cpsr.packed = MODE_SYSTEM;
 	cpu->spsr.packed = 0;
 
-	cpu->cyclesToEvent = 0;
+	cpu->cycles = 0;
+	cpu->nextEvent = INT_MAX;
 
 	cpu->shifterOperand = 0;
 	cpu->shifterCarryOut = 0;

@@ -79,12 +79,15 @@ void (*store8)(struct ARMMemory*, uint32_t address, int8_t value);
 
 	uint32_t* activeRegion;
 	uint32_t activeMask;
+	uint32_t activePrefetchCycles32;
+	uint32_t activePrefetchCycles16;
 	void (*setActiveRegion)(struct ARMMemory*, uint32_t address);
 };
 
 struct ARMBoard {
 	struct ARMCore* cpu;
 	void (*reset)(struct ARMBoard* board);
+	void (*nextEvent)(struct ARMBoard* board);
 	void (*swi16)(struct ARMBoard* board, int immediate);
 	void (*swi32)(struct ARMBoard* board, int immediate);
 
@@ -96,7 +99,8 @@ int32_t gprs[16];
 	union PSR cpsr;
 	union PSR spsr;
 
-	int32_t cyclesToEvent;
+	uint32_t cycles;
+	uint32_t nextEvent;
 
 	int32_t bankedRegisters[6][7];
 	int32_t bankedSPSRs[6];

@@ -106,71 +106,85 @@ } else {
 		switch (condition) {
 		case 0x0:
 			if (!ARM_COND_EQ) {
+				cpu->cycles += 1 + cpu->memory->activePrefetchCycles32;
 				return;
 			}
 			break;
 		case 0x1:
 			if (!ARM_COND_NE) {
+				cpu->cycles += 1 + cpu->memory->activePrefetchCycles32;
 				return;
 			}
 			break;
 		case 0x2:
 			if (!ARM_COND_CS) {
+				cpu->cycles += 1 + cpu->memory->activePrefetchCycles32;
 				return;
 			}
 			break;
 		case 0x3:
 			if (!ARM_COND_CC) {
+				cpu->cycles += 1 + cpu->memory->activePrefetchCycles32;
 				return;
 			}
 			break;
 		case 0x4:
 			if (!ARM_COND_MI) {
+				cpu->cycles += 1 + cpu->memory->activePrefetchCycles32;
 				return;
 			}
 			break;
 		case 0x5:
 			if (!ARM_COND_PL) {
+				cpu->cycles += 1 + cpu->memory->activePrefetchCycles32;
 				return;
 			}
 			break;
 		case 0x6:
 			if (!ARM_COND_VS) {
+				cpu->cycles += 1 + cpu->memory->activePrefetchCycles32;
 				return;
 			}
 			break;
 		case 0x7:
 			if (!ARM_COND_VC) {
+				cpu->cycles += 1 + cpu->memory->activePrefetchCycles32;
 				return;
 			}
 			break;
 		case 0x8:
 			if (!ARM_COND_HI) {
+				cpu->cycles += 1 + cpu->memory->activePrefetchCycles32;
 				return;
 			}
 			break;
 		case 0x9:
 			if (!ARM_COND_LS) {
+				cpu->cycles += 1 + cpu->memory->activePrefetchCycles32;
 				return;
 			}
 			break;
 		case 0xA:
 			if (!ARM_COND_GE) {
+				cpu->cycles += 1 + cpu->memory->activePrefetchCycles32;
 				return;
 			}
 			break;
 		case 0xB:
 			if (!ARM_COND_LT) {
+				cpu->cycles += 1 + cpu->memory->activePrefetchCycles32;
 				return;
 			}
 			break;
 		case 0xC:
 			if (!ARM_COND_GT) {
+				cpu->cycles += 1 + cpu->memory->activePrefetchCycles32;
 				return;
 			}
 			break;
 		case 0xD:
 			if (!ARM_COND_GE) {
+				cpu->cycles += 1 + cpu->memory->activePrefetchCycles32;
 				return;
 			}
 			break;
@@ -237,6 +251,7 @@
 #define DEFINE_INSTRUCTION_ARM(NAME, BODY) \
 	static void _ARMInstruction ## NAME (struct ARMCore* cpu, uint32_t opcode) { \
 		BODY; \
+		cpu->cycles += 1 + cpu->memory->activePrefetchCycles32; \
 	}
 
 #define DEFINE_ALU_INSTRUCTION_EX_ARM(NAME, S_BODY, SHIFTER, BODY, POST_BODY) \

@@ -95,6 +95,7 @@
 #define DEFINE_INSTRUCTION_THUMB(NAME, BODY) \
 	static void _ThumbInstruction ## NAME (struct ARMCore* cpu, uint16_t opcode) {  \
 		BODY; \
+		cpu->cycles += 1 + cpu->memory->activePrefetchCycles16; \
 	}
 
 #define DEFINE_IMMEDIATE_5_INSTRUCTION_EX_THUMB(NAME, IMMEDIATE, BODY) \

@@ -9,6 +9,9 @@ static const char* GBA_CANNOT_MMAP = "Could not map memory";
 
 static void GBASetActiveRegion(struct ARMMemory* memory, uint32_t region);
 
+static const char GBA_BASE_WAITSTATES[16] = { 0, 0, 2, 0, 0, 0, 0, 0, 4, 4, 4, 4, 4, 4, 4 };
+static const char GBA_BASE_WAITSTATES_SEQ[16] = { 0, 0, 2, 0, 0, 0, 0, 0, 2, 2, 4, 4, 8, 8, 4 };
+
 void GBAMemoryInit(struct GBAMemory* memory) {
 	memory->d.load32 = GBALoad32;
 	memory->d.load16 = GBALoad16;
@@ -31,6 +34,20 @@ memory->p->errno = GBA_OUT_OF_MEMORY;
 		memory->p->errstr = GBA_CANNOT_MMAP;
 	}
 
+	int i;
+	for (i = 0; i < 16; ++i) {
+		memory->waitstates16[i] = GBA_BASE_WAITSTATES[i];
+		memory->waitstatesSeq16[i] = GBA_BASE_WAITSTATES_SEQ[i];
+		memory->waitstates32[i] = GBA_BASE_WAITSTATES[i] + GBA_BASE_WAITSTATES_SEQ[i] + 1;
+		memory->waitstatesSeq32[i] = GBA_BASE_WAITSTATES_SEQ[i] + GBA_BASE_WAITSTATES_SEQ[i] + 1;
+	}
+	for (; i < 256; ++i) {
+		memory->waitstates16[i] = 0;
+		memory->waitstatesSeq16[i] = 0;
+		memory->waitstates32[i] = 0;
+		memory->waitstatesSeq32[i] = 0;
+	}
+
 	memory->d.activeRegion = 0;
 	memory->d.activeMask = 0;
 	memory->d.setActiveRegion = GBASetActiveRegion;
@@ -44,6 +61,8 @@
 static void GBASetActiveRegion(struct ARMMemory* memory, uint32_t address) {
 	struct GBAMemory* gbaMemory = (struct GBAMemory*) memory;
 
+	memory->activePrefetchCycles32 = gbaMemory->waitstates32[address >> BASE_OFFSET];
+	memory->activePrefetchCycles16 = gbaMemory->waitstates16[address >> BASE_OFFSET];
 	switch (address & ~OFFSET_MASK) {
 	case BASE_BIOS:
 		memory->activeRegion = gbaMemory->bios;

@@ -55,7 +55,8 @@ SIZE_CART_EEPROM = 0x00002000
 };
 
 enum {
-	OFFSET_MASK = 0x00FFFFFF
+	OFFSET_MASK = 0x00FFFFFF,
+	BASE_OFFSET = 24
 };
 
 struct GBAMemory {
@@ -67,6 +68,11 @@ uint32_t* wram;
 	uint32_t* iwram;
 	uint32_t* rom;
 	uint16_t io[SIZE_IO >> 1];
+
+	char waitstates32[256];
+	char waitstates16[256];
+	char waitstatesSeq32[256];
+	char waitstatesSeq16[256];
 };
 
 int32_t GBALoad32(struct ARMMemory* memory, uint32_t address);