M src/gba/gba-bios.c → src/gba/gba-bios.c

@@ -7,6 +7,9 @@
 #include <math.h>
 #include <stdlib.h>
 
+const uint32_t GBA_BIOS_CHECKSUM = 0xBAAE187F;
+const uint32_t GBA_DS_BIOS_CHECKSUM = 0xBAAE1880;
+
 static void _unLz77(struct GBAMemory* memory, uint32_t source, uint8_t* dest);
 static void _unHuffman(struct GBAMemory* memory, uint32_t source, uint32_t* dest);
 static void _unRl(struct GBAMemory* memory, uint32_t source, uint8_t* dest);
@@ -237,6 +240,8 @@ break;
 	case 0xC:
 		_FastCpuSet(gba);
 		break;
+	case 0xD:
+		gba->cpu.gprs[0] = GBAChecksum(gba->memory.bios, SIZE_BIOS);
 	case 0xE:
 		_BgAffineSet(gba);
 		break;
@@ -315,6 +320,15 @@ }
 
 void GBASwi32(struct ARMBoard* board, int immediate) {
 	GBASwi16(board, immediate >> 16);
+}
+
+uint32_t GBAChecksum(uint32_t* memory, size_t size) {
+	size_t i;
+	uint32_t sum = 0;
+	for (i = 0; i < size; i += 4) {
+		sum += memory[i >> 2];
+	}
+	return sum;
 }
 
 static void _unLz77(struct GBAMemory* memory, uint32_t source, uint8_t* dest) {

M src/gba/gba-bios.h → src/gba/gba-bios.h

@@ -3,7 +3,13 @@ #define GBA_BIOS_H
 
 #include "arm.h"
 
+#include <string.h>
+
 void GBASwi16(struct ARMBoard* board, int immediate);
 void GBASwi32(struct ARMBoard* board, int immediate);
+
+uint32_t GBAChecksum(uint32_t* memory, size_t size);
+const uint32_t GBA_BIOS_CHECKSUM;
+const uint32_t GBA_DS_BIOS_CHECKSUM;
 
 #endif

M src/gba/gba.c → src/gba/gba.c

@@ -360,6 +360,15 @@
 void GBALoadBIOS(struct GBA* gba, int fd) {
 	gba->memory.bios = fileMemoryMap(fd, SIZE_BIOS, MEMORY_READ);
 	gba->memory.fullBios = 1;
+	uint32_t checksum = GBAChecksum(gba->memory.bios, SIZE_BIOS);
+	GBALog(gba, GBA_LOG_DEBUG, "BIOS Checksum: 0x%X", checksum);
+	if (checksum == GBA_BIOS_CHECKSUM) {
+		GBALog(gba, GBA_LOG_INFO, "Official GBA BIOS detected");
+	} else if (checksum == GBA_DS_BIOS_CHECKSUM) {
+		GBALog(gba, GBA_LOG_INFO, "Official GBA (DS) BIOS detected");
+	} else {
+		GBALog(gba, GBA_LOG_WARN, "BIOS checksum incorrect");
+	}
 	if ((gba->cpu.gprs[ARM_PC] >> BASE_OFFSET) == BASE_BIOS) {
 		gba->memory.d.setActiveRegion(&gba->memory.d, gba->cpu.gprs[ARM_PC]);
 	}