Fix bug gen2 addItem

examples/Makefile

@@ -8,6 +8,7 @@ all:
 	$(MAKE) -C encodeText_gen2 $(MAKECMDGOALS) $(MAKEOVERRIDES)
 	$(MAKE) -C decodeSprite $(MAKECMDGOALS) $(MAKEOVERRIDES)
 	$(MAKE) -C addDistributionPoke $(MAKECMDGOALS) $(MAKEOVERRIDES)
+	$(MAKE) -C gen2_gsball $(MAKECMDGOALS) $(MAKEOVERRIDES)
 
 clean:
 	$(MAKE) -C do_stuff_gen1 clean
@@ -16,3 +17,4 @@ clean:
 	$(MAKE) -C encodeText_gen2 clean
 	$(MAKE) -C decodeSprite clean
 	$(MAKE) -C addDistributionPoke clean
+	$(MAKE) -C gen2_gsball clean

examples/gen2_gsball/Makefile

@@ -0,0 +1,48 @@
+# # Compiler flags
+CXXFLAGS := -std=c++11 -fno-rtti -fno-exceptions -fno-unwind-tables -Wall -Wextra -I $(CURDIR) -I $(CURDIR)/../../include -g -Os
+
+# Source files directory
+SRC_DIR := .
+# Build directory
+BUILD_DIR := build
+
+# Source files (add more as needed)
+SRCS := $(shell find $(SRC_DIR) -type f -name '*.cpp')
+# Object files
+OBJS := $(patsubst $(SRC_DIR)/%.cpp,$(BUILD_DIR)/%.o,$(SRCS))
+
+LIBS := -lpokemegb
+ifeq ($(PNG_SUPPORT),1)
+	LIBS += -lpng
+endif
+
+# Ensure necessary directories exist
+# This function ensures the directory for the target exists
+define make_directory
+	@mkdir -p $(dir $@)
+endef
+
+# Target executable
+TARGET := ../../gen2_gsball
+
+# Phony targets
+.PHONY: all clean
+
+# Default target
+all: $(TARGET)
+
+$(TARGET): $(OBJS)
+	$(CXX) $(CXXFLAGS) $^ -o $@ $(LIBS) -L ../../
+
+# Rule to compile source files
+$(BUILD_DIR)/%.o: $(SRC_DIR)/%.cpp | $(BUILD_DIR)
+	$(make_directory)
+	$(CXX) $(CXXFLAGS) -c $< -o $@
+
+# Create the build directory if it doesn't exist
+$(BUILD_DIR):
+	mkdir -p $(BUILD_DIR)
+
+# Clean rule
+clean:
+	rm -rf $(BUILD_DIR) $(TARGET)

examples/gen2_gsball/main.cpp

@@ -0,0 +1,116 @@
+#include "gen1/Gen1GameReader.h"
+#include "gen1/Gen1DistributionPokemon.h"
+#include "gen2/Gen2GameReader.h"
+#include "gen2/Gen2DistributionPokemon.h"
+#include "RomReader.h"
+#include "SaveManager.h"
+#include "SpriteRenderer.h"
+#include "utils.h"
+
+#include <cstdio>
+#include <cstring>
+#include <cstdlib>
+
+#define POKEMON_CRYSTAL_ITEM_ID_GS_BALL 0x73
+
+static void gen2ReceiveGSBall(Gen2GameReader& gameReader)
+{
+    bool alreadyHasOne = false;
+
+    const char* trainerName = gameReader.getTrainerName();
+    Gen2ItemList keyItemPocket = gameReader.getItemList(Gen2ItemListType::GEN2_ITEMLISTTYPE_KEYITEMPOCKET);
+    if(keyItemPocket.getCount() > 0)
+    {
+        uint8_t itemId;
+        uint8_t itemCount;
+        bool gotEntry = keyItemPocket.getEntry(0, itemId, itemCount);
+
+        while(gotEntry)
+        {
+            if(itemId == POKEMON_CRYSTAL_ITEM_ID_GS_BALL)
+            {
+                alreadyHasOne = true;
+                break;
+            }
+            gotEntry = keyItemPocket.getNextEntry(itemId, itemCount);
+        }
+    }
+    
+    if(alreadyHasOne)
+    {
+        fprintf(stderr, "ERROR: It appears you already have one!");
+    }
+    else
+    {
+        keyItemPocket.add(POKEMON_CRYSTAL_ITEM_ID_GS_BALL, 1);
+        gameReader.finishSave();
+        fprintf(stdout, "%s obtained a GS Ball!", trainerName);
+    }
+}
+
+int main(int argc, char** argv)
+{
+    if(argc != 3)
+    {
+        fprintf(stderr, "Usage: addDistributionPoke <path/to/rom.gbc> <path/to/file.sav>\n");
+        return 1;
+    }
+
+    uint8_t* romBuffer;
+    uint8_t* saveBuffer;
+    uint32_t romFileSize;
+    uint32_t saveFileSize;
+
+    romBuffer = readFileIntoBuffer(argv[1], romFileSize);
+    if(!romBuffer)
+    {
+        fprintf(stderr, "ERROR: Couldn't read file %s\n", argv[1]);
+        return 1;
+    }
+    saveBuffer = readFileIntoBuffer(argv[2], saveFileSize);
+    if(!saveBuffer)
+    {
+        fprintf(stderr, "ERROR: Couldn't read file %s\n", argv[2]);
+        return 1;
+    }
+
+    GameboyCartridgeHeader cartridgeHeader;
+    BufferBasedRomReader romReader(romBuffer, romFileSize);
+    BufferBasedSaveManager saveManager(saveBuffer, saveFileSize);
+
+    readGameboyCartridgeHeader(romReader, cartridgeHeader);
+
+    //check if we're dealing with gen 2
+    const Gen2GameType gen2Type = gen2_determineGameType(cartridgeHeader);
+    if(gen2Type == Gen2GameType::INVALID)
+    {
+        fprintf(stderr, "ERROR: not a gen 2 game!\n");
+        return 1;
+    }
+    if(gen2Type != Gen2GameType::CRYSTAL)
+    {
+        fprintf(stderr, "ERROR: not Pokémon Crystal!\n");
+//        return 1;
+    }
+    
+    Gen2GameReader gameReader(romReader, saveManager, gen2Type);
+    gen2ReceiveGSBall(gameReader);
+
+    // Test for adding rare candy
+#if 0
+    Gen2ItemList itemPocket = gameReader.getItemList(Gen2ItemListType::GEN2_ITEMLISTTYPE_ITEMPOCKET);
+    itemPocket.add(0x20, 27);
+    gameReader.finishSave();
+#endif
+
+    FILE* f = fopen(argv[2], "w");
+    fwrite(saveBuffer, 1, saveFileSize, f);
+    fclose(f);
+
+    free(romBuffer);
+    free(saveBuffer);
+    romBuffer = 0;
+    saveBuffer = 0;
+    
+    return 0;
+}

src/gen2/Gen2Common.cpp

@@ -155,7 +155,7 @@ uint8_t Gen2ItemList::getCount()
 
 uint8_t Gen2ItemList::getCapacity()
 {
-	return 20;
+	return (type_ == Gen2ItemListType::GEN2_ITEMLISTTYPE_KEYITEMPOCKET) ? 26 : 20;
 }
 
 bool Gen2ItemList::getEntry(uint8_t index, uint8_t &outItemId, uint8_t &outCount)
@@ -165,7 +165,11 @@ bool Gen2ItemList::getEntry(uint8_t index, uint8_t &outItemId, uint8_t &outCount
 		return false;
 	}
 
-	if (!saveManager_.advance(1 + (index * 2)))
+	// It looks like the key item pocket doesn't have a count value.
+	// During my test if I try to write a GS ball with count 1 to crystal and store the count value, I get a random master ball showing up (which has itemId 1)
+	// before the gs ball in the list.
+	const uint32_t advanceAmount = (type_ == Gen2ItemListType::GEN2_ITEMLISTTYPE_KEYITEMPOCKET) ? 1 + index : 1 + (index * 2);
+	if (!saveManager_.advance(advanceAmount))
 	{
 		return false;
 	}
@@ -183,8 +187,20 @@ bool Gen2ItemList::getNextEntry(uint8_t &outItemId, uint8_t &outCount)
 		return false;
 	}
 
-	saveManager_.readByte(outCount);
+	// 2 things here:
+	// - The bulbapedia article: https://bulbapedia.bulbagarden.net/wiki/Save_data_structure_(Generation_II)#Item_lists
+	//   gets the order of count vs itemId wrong. At least during my tests with a Pokémon crystal AND gold save
+	// - The key item pocket doesn't appear to store a count value at all.
+	//   see my other comment at ::getEntry() for more info
 	saveManager_.readByte(outItemId);
+	if(type_ != Gen2ItemListType::GEN2_ITEMLISTTYPE_KEYITEMPOCKET)
+	{
+		saveManager_.readByte(outCount);
+	}
+	else
+	{
+		outCount = 1;
+	}
 
 	return true;
 }
@@ -203,13 +219,19 @@ bool Gen2ItemList::add(uint8_t itemId, uint8_t itemCount)
 	{
 		if(curItemId == itemId)
 		{
-			uint8_t newCount = curItemCount + itemCount;
+			// the key item pocket doesn't appear to have a count field per entry.
-			if(newCount > 99)
+			// For more info see the related comment @getEntry()
+			if(type_ != Gen2ItemListType::GEN2_ITEMLISTTYPE_KEYITEMPOCKET)
 			{
-				newCount = 99;
+				uint8_t newCount = curItemCount + itemCount;
+				if(newCount > 99)
+				{
+					newCount = 99;
+				}
+				saveManager_.rewind(1); // count is the second field of each entry (yes, Bulbapedia appears to get it wrong here)
+				saveManager_.writeByte(newCount);
+				saveManager_.advance();
 			}
-			saveManager_.rewind();
-			saveManager_.writeByte(newCount);
 			return true;
 		}
 	}
@@ -221,12 +243,19 @@ bool Gen2ItemList::add(uint8_t itemId, uint8_t itemCount)
 		return false;
 	}
 	
+	// Bulbapedia gets the order wrong here. itemId should go first, then itemCount
+	// at least this is the case during my tests with a Pokémon Crystal AND Gold save
+	saveManager_.writeByte(itemId);
 	// in the while loop, getNextEntry has returned false on the last iteration, so that means
 	// we've arrived at the terminator of the list. This is the exact position at which we need to write our new entry.
 	// convenient, isn't it?
 	// so let's write the new entry...
-	saveManager_.writeByte(itemCount);
+	if(type_ != Gen2ItemListType::GEN2_ITEMLISTTYPE_KEYITEMPOCKET)
-	saveManager_.writeByte(itemId);
+	{
+		// the key item pocket doesn't appear to have a count field per entry.
+		// For more info see the related comment @getEntry()
+		saveManager_.writeByte(itemCount);
+	}
 	// now write the new terminator
 	saveManager_.writeByte(0xFF);