From 273d2db575de606126b68e52dd04c71d8969dbcf Mon Sep 17 00:00:00 2001
From: Jeffrey Pfau <jeffrey@endrift.com>
Date: Sun, 8 May 2016 23:18:42 -0700
Subject: [PATCH] GB: Add partial Game Genie support

---
 src/gb/cheats.c   | 74 +++++++++++++++++++++++++++++++++++++++++------
 src/gb/cheats.h   |  6 ++--
 src/gba/cheats.h  |  1 -
 src/util/string.c | 47 ++++++++++++++++++++++++++++++
 src/util/string.h |  3 ++
 5 files changed, 118 insertions(+), 13 deletions(-)

diff --git a/src/gb/cheats.c b/src/gb/cheats.c
index 2c50b1256..95489a1c5 100644
--- a/src/gb/cheats.c
+++ b/src/gb/cheats.c
@@ -5,8 +5,43 @@
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 #include "cheats.h"
 
+#include "core/core.h"
+#include "gb/memory.h"
 #include "util/string.h"
 
+DEFINE_VECTOR(GBCheatPatchList, struct GBCheatPatch);
+
+static void _patchROM(struct mCheatDevice* device, struct GBCheatSet* cheats) {
+	if (!device->p) {
+		return;
+	}
+	size_t i;
+	for (i = 0; i < GBCheatPatchListSize(&cheats->romPatches); ++i) {
+		struct GBCheatPatch* patch = GBCheatPatchListGetPointer(&cheats->romPatches, i);
+		if (patch->applied) {
+			continue;
+		}
+		// TODO: Byte check
+		GBPatch8(device->p->cpu, patch->address, patch->newValue, &patch->oldValue);
+		patch->applied = true;
+	}
+}
+
+static void _unpatchROM(struct mCheatDevice* device, struct GBCheatSet* cheats) {
+	if (!device->p) {
+		return;
+	}
+	size_t i;
+	for (i = 0; i < GBCheatPatchListSize(&cheats->romPatches); ++i) {
+		struct GBCheatPatch* patch = GBCheatPatchListGetPointer(&cheats->romPatches, i);
+		if (!patch->applied) {
+			continue;
+		}
+		GBPatch8(device->p->cpu, patch->address, patch->oldValue, NULL);
+		patch->applied = false;
+	}
+}
+
 static void GBCheatSetDeinit(struct mCheatSet* set);
 static void GBCheatAddSet(struct mCheatSet* cheats, struct mCheatDevice* device);
 static void GBCheatRemoveSet(struct mCheatSet* cheats, struct mCheatDevice* device);
@@ -19,6 +54,8 @@ static struct mCheatSet* GBCheatSetCreate(struct mCheatDevice* device, const cha
 	struct GBCheatSet* set = malloc(sizeof(*set));
 	mCheatSetInit(&set->d, name);
 
+	GBCheatPatchListInit(&set->romPatches, 0);
+
 	set->d.deinit = GBCheatSetDeinit;
 	set->d.add = GBCheatAddSet;
 	set->d.remove = GBCheatRemoveSet;
@@ -39,19 +76,17 @@ struct mCheatDevice* GBCheatDeviceCreate(void) {
 
 static void GBCheatSetDeinit(struct mCheatSet* set) {
 	struct GBCheatSet* gbset = (struct GBCheatSet*) set;
-	UNUSED(gbset);
+	GBCheatPatchListDeinit(&gbset->romPatches);
 }
 
 static void GBCheatAddSet(struct mCheatSet* cheats, struct mCheatDevice* device) {
 	struct GBCheatSet* gbset = (struct GBCheatSet*) cheats;
-	UNUSED(gbset);
-	UNUSED(device);
+	_patchROM(device, gbset);
 }
 
 static void GBCheatRemoveSet(struct mCheatSet* cheats, struct mCheatDevice* device) {
 	struct GBCheatSet* gbset = (struct GBCheatSet*) cheats;
-	UNUSED(gbset);
-	UNUSED(device);
+	_unpatchROM(device, gbset);
 }
 
 static bool GBCheatAddCodebreaker(struct GBCheatSet* cheats, uint16_t address, uint8_t data) {
@@ -77,6 +112,28 @@ static bool GBCheatAddGameSharkLine(struct GBCheatSet* cheats, const char* line)
 	return GBCheatAddGameShark(cheats, op);
 }
 
+static bool GBCheatAddGameGenieLine(struct GBCheatSet* cheats, const char* line) {
+	uint16_t op1;
+	uint16_t op2;
+	const char* lineNext = hex12(line, &op1);
+	if (!lineNext || lineNext[0] != '-') {
+		return false;
+	}
+	++lineNext;
+	lineNext = hex12(lineNext, &op2);
+	if (!lineNext) {
+		return false;
+	}
+	uint16_t address = (op1 & 0xF) << 8;
+	address |= (op2 >> 4) & 0xFF;
+	address |= ((op2 & 0xF) ^ 0xF) << 12;
+	struct GBCheatPatch* patch = GBCheatPatchListAppend(&cheats->romPatches);
+	patch->address = address;
+	patch->newValue = op1 >> 4;
+	patch->applied = false;
+	return true;
+}
+
 static bool GBCheatAddVBALine(struct GBCheatSet* cheats, const char* line) {
 	uint16_t address;
 	uint8_t value;
@@ -103,7 +160,7 @@ bool GBCheatAddLine(struct mCheatSet* set, const char* line, int type) {
 	case GB_CHEAT_AUTODETECT:
 		break;
 	case GB_CHEAT_GAME_GENIE:
-		return false;
+		return GBCheatAddGameGenieLine(cheats, line);
 	case GB_CHEAT_GAMESHARK:
 		return GBCheatAddGameSharkLine(cheats, line);
 	case GB_CHEAT_VBA:
@@ -118,7 +175,7 @@ bool GBCheatAddLine(struct mCheatSet* set, const char* line, int type) {
 	bool codebreaker = false;
 	const char* lineNext = hex16(line, &op1);
 	if (!lineNext) {
-		return false;
+		return GBCheatAddGameGenieLine(cheats, line);
 	}
 	if (lineNext[0] == ':') {
 		return GBCheatAddVBALine(cheats, line);
@@ -148,8 +205,7 @@ bool GBCheatAddLine(struct mCheatSet* set, const char* line, int type) {
 
 static void GBCheatRefresh(struct mCheatSet* cheats, struct mCheatDevice* device) {
 	struct GBCheatSet* gbset = (struct GBCheatSet*) cheats;
-	UNUSED(gbset);
-	UNUSED(device);
+	_patchROM(device, gbset);
 }
 
 static void GBCheatSetCopyProperties(struct mCheatSet* set, struct mCheatSet* oldSet) {
diff --git a/src/gb/cheats.h b/src/gb/cheats.h
index b8093def2..67fcfce12 100644
--- a/src/gb/cheats.h
+++ b/src/gb/cheats.h
@@ -11,8 +11,6 @@
 #include "core/cheats.h"
 #include "util/vector.h"
 
-#define MAX_ROM_PATCHES 4
-
 enum GBACheatType {
 	GB_CHEAT_AUTODETECT,
 	GB_CHEAT_GAMESHARK,
@@ -25,11 +23,13 @@ struct GBCheatPatch {
 	int8_t newValue;
 	int8_t oldValue;
 	bool applied;
-	bool exists;
 };
 
+DECLARE_VECTOR(GBCheatPatchList, struct GBCheatPatch);
+
 struct GBCheatSet {
 	struct mCheatSet d;
+	struct GBCheatPatchList romPatches;
 };
 
 struct mCheatDevice* GBCheatDeviceCreate(void);
diff --git a/src/gba/cheats.h b/src/gba/cheats.h
index 784124430..138c83880 100644
--- a/src/gba/cheats.h
+++ b/src/gba/cheats.h
@@ -10,7 +10,6 @@
 
 #include "arm/arm.h"
 #include "core/cheats.h"
-#include "util/vector.h"
 
 #define MAX_ROM_PATCHES 4
 
diff --git a/src/util/string.c b/src/util/string.c
index 6649a38ac..a2a23dea0 100644
--- a/src/util/string.c
+++ b/src/util/string.c
@@ -260,6 +260,22 @@ const char* hex32(const char* line, uint32_t* out) {
 	return line;
 }
 
+const char* hex24(const char* line, uint32_t* out) {
+	uint32_t value = 0;
+	int i;
+	for (i = 0; i < 6; ++i, ++line) {
+		char digit = *line;
+		value <<= 4;
+		int nybble = hexDigit(digit);
+		if (nybble < 0) {
+			return 0;
+		}
+		value |= nybble;
+	}
+	*out = value;
+	return line;
+}
+
 const char* hex16(const char* line, uint16_t* out) {
 	uint16_t value = 0;
 	*out = 0;
@@ -277,6 +293,23 @@ const char* hex16(const char* line, uint16_t* out) {
 	return line;
 }
 
+const char* hex12(const char* line, uint16_t* out) {
+	uint16_t value = 0;
+	*out = 0;
+	int i;
+	for (i = 0; i < 3; ++i, ++line) {
+		char digit = *line;
+		value <<= 4;
+		int nybble = hexDigit(digit);
+		if (nybble < 0) {
+			return 0;
+		}
+		value |= nybble;
+	}
+	*out = value;
+	return line;
+}
+
 const char* hex8(const char* line, uint8_t* out) {
 	uint8_t value = 0;
 	*out = 0;
@@ -293,3 +326,17 @@ const char* hex8(const char* line, uint8_t* out) {
 	*out = value;
 	return line;
 }
+
+const char* hex4(const char* line, uint8_t* out) {
+	uint8_t value = 0;
+	*out = 0;
+	char digit = *line;
+	value <<= 4;
+	int nybble = hexDigit(digit);
+	if (nybble < 0) {
+		return 0;
+	}
+	value |= nybble;
+	*out = value;
+	return line;
+}
diff --git a/src/util/string.h b/src/util/string.h
index b209f7d90..9716cfbf6 100644
--- a/src/util/string.h
+++ b/src/util/string.h
@@ -26,7 +26,10 @@ uint32_t utf16Char(const uint16_t** unicode, size_t* length);
 
 int hexDigit(char digit);
 const char* hex32(const char* line, uint32_t* out);
+const char* hex24(const char* line, uint32_t* out);
 const char* hex16(const char* line, uint16_t* out);
+const char* hex12(const char* line, uint16_t* out);
 const char* hex8(const char* line, uint8_t* out);
+const char* hex4(const char* line, uint8_t* out);
 
 #endif