M src/arm.c → src/arm.c

@@ -1,6 +1,8 @@
 #include "arm.h"
 
+#include "isa-arm.h"
 #include "isa-inlines.h"
+#include "isa-thumb.h"
 
 static inline enum RegisterBank _ARMSelectBank(enum PrivilegeMode);
 
@@ -107,7 +109,7 @@ cpu->board->reset(cpu->board);
 }
 
 void ARMRun(struct ARMCore* cpu) {
-	if (cpu->executionMode) {
+	if (cpu->executionMode == MODE_THUMB) {
 		ThumbStep(cpu);
 	} else {
 		ARMStep(cpu);

M src/isa-arm.c → src/isa-arm.c

@@ -126,10 +126,6 @@
 // Instruction definitions
 // Beware pre-processor antics
 
-#define ARM_WRITE_PC \
-	cpu->gprs[ARM_PC] = (cpu->gprs[ARM_PC] & -WORD_SIZE_ARM) + WORD_SIZE_ARM; \
-	cpu->memory->setActiveRegion(cpu->memory, cpu->gprs[ARM_PC]);
-
 #define ARM_ADDITION_S(M, N, D) \
 	if (rd == ARM_PC && _ARMModeHasSPSR(cpu->cpsr.priv)) { \
 		cpu->cpsr = cpu->spsr; \
@@ -412,7 +408,15 @@ cpu->gprs[ARM_PC] += offset; \
 	ARM_WRITE_PC;)
 
 DEFINE_INSTRUCTION_ARM(BL, ARM_STUB)
-DEFINE_INSTRUCTION_ARM(BX, ARM_STUB)
+DEFINE_INSTRUCTION_ARM(BX, \
+	int rm = opcode & 0x0000000F; \
+	_ARMSetMode(cpu, cpu->gprs[rm] & 0x00000001); \
+	cpu->gprs[ARM_PC] = cpu->gprs[rm] & 0xFFFFFFFE; \
+	if (cpu->executionMode == MODE_THUMB) { \
+		THUMB_WRITE_PC;
+	} else { \
+		ARM_WRITE_PC; \
+	})
 
 // End branch definitions
 

M src/isa-inlines.h → src/isa-inlines.h

@@ -54,6 +54,14 @@ #define ARM_V_SUBTRACTION(M, N, D) ((ARM_SIGN((M) ^ (N))) && (ARM_SIGN((M) ^ (D))))
 
 #define ARM_STUB cpu->board->hitStub(cpu->board, opcode)
 
+#define ARM_WRITE_PC \
+	cpu->gprs[ARM_PC] = (cpu->gprs[ARM_PC] & -WORD_SIZE_ARM) + WORD_SIZE_ARM; \
+	cpu->memory->setActiveRegion(cpu->memory, cpu->gprs[ARM_PC]);
+
+#define THUMB_WRITE_PC \
+	cpu->gprs[ARM_PC] = (cpu->gprs[ARM_PC] & -WORD_SIZE_THUMB) + WORD_SIZE_THUMB; \
+	cpu->memory->setActiveRegion(cpu->memory, cpu->gprs[ARM_PC]);
+
 static inline int _ARMModeHasSPSR(enum PrivilegeMode mode) {
 	return mode != MODE_SYSTEM && mode != MODE_USER;
 }