From f84aadffd2d02827f095c58bce224172875393f1 Mon Sep 17 00:00:00 2001
From: Jeffrey Pfau <jeffrey@endrift.com>
Date: Sat, 26 Dec 2015 22:25:50 -0500
Subject: [PATCH] GBA: Support for VBA-style cheat codes

---
 CHANGES           |  1 +
 src/gba/cheats.c  | 59 +++++++++++++++++++++++++++++++++++++++--------
 src/gba/cheats.h  |  2 ++
 src/util/string.c | 17 ++++++++++++++
 src/util/string.h |  1 +
 5 files changed, 71 insertions(+), 9 deletions(-)

diff --git a/CHANGES b/CHANGES
index b13d91035..289a2dd27 100644
--- a/CHANGES
+++ b/CHANGES
@@ -7,6 +7,7 @@ Features:
  - Libretro: Cheat code support
  - Support for GLSL shaders
  - ROM information view
+ - Support for VBA-style cheat codes
 Bugfixes:
  - Util: Fix PowerPC PNG read/write pixel order
  - VFS: Fix VFileReadline and remove _vfdReadline
diff --git a/src/gba/cheats.c b/src/gba/cheats.c
index 5f7aee24d..0bbd2b06b 100644
--- a/src/gba/cheats.c
+++ b/src/gba/cheats.c
@@ -359,26 +359,67 @@ bool GBACheatSaveFile(struct GBACheatDevice* device, struct VFile* vf) {
 	return true;
 }
 
+bool GBACheatAddVBALine(struct GBACheatSet* cheats, const char* line) {
+	uint32_t address;
+	uint8_t op;
+	uint32_t value = 0;
+	int width = 0;
+	const char* lineNext = hex32(line, &address);
+	if (!lineNext) {
+		return false;
+	}
+	if (lineNext[0] != ':') {
+		return false;
+	}
+	++lineNext;
+	while (width < 4) {
+		lineNext = hex8(lineNext, &op);
+		if (!lineNext) {
+			break;
+		}
+		value <<= 8;
+		value |= op;
+		++width;
+	}
+	if (width == 0 || width == 3) {
+		return false;
+	}
+
+	struct GBACheat* cheat = GBACheatListAppend(&cheats->list);
+	cheat->address = address;
+	cheat->operandOffset = 0;
+	cheat->addressOffset = 0;
+	cheat->repeat = 1;
+	cheat->type = CHEAT_ASSIGN;
+	cheat->width = width;
+	cheat->operand = value;
+	GBACheatRegisterLine(cheats, line);
+	return true;
+}
+
 bool GBACheatAddLine(struct GBACheatSet* cheats, const char* line) {
 	uint32_t op1;
 	uint16_t op2;
 	uint16_t op3;
-	line = hex32(line, &op1);
-	if (!line) {
+	const char* lineNext = hex32(line, &op1);
+	if (!lineNext) {
 		return false;
 	}
-	while (isspace((int) line[0])) {
-		++line;
+	if (lineNext[0] == ':') {
+		return GBACheatAddVBALine(cheats, line);
 	}
-	line = hex16(line, &op2);
-	if (!line) {
+	while (isspace((int) lineNext[0])) {
+		++lineNext;
+	}
+	lineNext = hex16(lineNext, &op2);
+	if (!lineNext) {
 		return false;
 	}
-	if (!line[0] || isspace((int) line[0])) {
+	if (!lineNext[0] || isspace((int) lineNext[0])) {
 		return GBACheatAddCodeBreaker(cheats, op1, op2);
 	}
-	line = hex16(line, &op3);
-	if (!line) {
+	lineNext = hex16(lineNext, &op3);
+	if (!lineNext) {
 		return false;
 	}
 	uint32_t realOp2 = op2;
diff --git a/src/gba/cheats.h b/src/gba/cheats.h
index 75a12622b..73b08940a 100644
--- a/src/gba/cheats.h
+++ b/src/gba/cheats.h
@@ -211,6 +211,8 @@ bool GBACheatAddGameSharkLine(struct GBACheatSet*, const char* line);
 bool GBACheatAddProActionReplay(struct GBACheatSet*, uint32_t op1, uint32_t op2);
 bool GBACheatAddProActionReplayLine(struct GBACheatSet*, const char* line);
 
+bool GBACheatAddVBALine(struct GBACheatSet*, const char* line);
+
 bool GBACheatAddAutodetect(struct GBACheatSet*, uint32_t op1, uint32_t op2);
 
 bool GBACheatParseFile(struct GBACheatDevice*, struct VFile*);
diff --git a/src/util/string.c b/src/util/string.c
index 91451a27d..6649a38ac 100644
--- a/src/util/string.c
+++ b/src/util/string.c
@@ -276,3 +276,20 @@ const char* hex16(const char* line, uint16_t* out) {
 	*out = value;
 	return line;
 }
+
+const char* hex8(const char* line, uint8_t* out) {
+	uint8_t value = 0;
+	*out = 0;
+	int i;
+	for (i = 0; i < 2; ++i, ++line) {
+		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 2597cbfda..b209f7d90 100644
--- a/src/util/string.h
+++ b/src/util/string.h
@@ -27,5 +27,6 @@ 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* hex16(const char* line, uint16_t* out);
+const char* hex8(const char* line, uint8_t* out);
 
 #endif