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GBA: Improve multiboot detection

This commit is contained in:
Jeffrey Pfau 2015-11-05 20:58:52 -08:00
parent 0faa6dd8ac
commit 2b5b8a0d6a
1 changed files with 19 additions and 6 deletions
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25
src/gba/gba.c
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@ -5,6 +5,9 @@
* file, You can obtain one at http://mozilla.org/MPL/2.0/. */
#include "gba.h"
#include "arm/decoder.h"
#include "arm/isa-inlines.h"
#include "gba/bios.h"
#include "gba/cheats.h"
#include "gba/io.h"
@ -13,8 +16,6 @@
#include "gba/serialize.h"
#include "gba/sio.h"
#include "isa-inlines.h"
#include "util/crc32.h"
#include "util/memory.h"
#include "util/math.h"
@ -27,8 +28,7 @@ const uint32_t GBA_COMPONENT_MAGIC = 0x1000000;
static const size_t GBA_ROM_MAGIC_OFFSET = 3;
static const uint8_t GBA_ROM_MAGIC[] = { 0xEA };
static const size_t GBA_MB_MAGIC_OFFSET = 0xC1;
static const uint8_t GBA_MB_MAGIC[] = { 0x00, 0x00, 0xEA };
static const size_t GBA_MB_MAGIC_OFFSET = 0xC0;
static void GBAInit(struct ARMCore* cpu, struct ARMComponent* component);
static void GBAInterruptHandlerInit(struct ARMInterruptHandler* irqh);
@ -727,11 +727,24 @@ bool GBAIsMB(struct VFile* vf) {
if (vf->seek(vf, GBA_MB_MAGIC_OFFSET, SEEK_SET) < 0) {
return false;
}
uint8_t signature[sizeof(GBA_MB_MAGIC)];
uint8_t signature[sizeof(uint32_t)];
if (vf->read(vf, &signature, sizeof(signature)) != sizeof(signature)) {
return false;
}
return memcmp(signature, GBA_MB_MAGIC, sizeof(signature)) == 0;
uint32_t opcode;
LOAD_32(opcode, 0, signature);
struct ARMInstructionInfo info;
ARMDecodeARM(opcode, &info);
if (info.branchType != ARM_BRANCH) {
return false;
}
if (info.op1.immediate <= 0) {
return false;
} else if (info.op1.immediate != 24) {
return true;
}
// Found a libgba-linked cart...these are a bit harder to detect.
return false;
}
bool GBAIsBIOS(struct VFile* vf) {