make the engineering around kUninitializedSaveDataValue not so horrible; affects "Daigassou! Band Brothers DX" but not tested (make the slot1comp_mc configure the BackupDevice with the appropriate uninitializedValue since it is a property of the physical backup memory hardware)

desmume/src/addons/slot1_retail_mcrom.cpp

@@ -48,6 +48,7 @@ public:
 		protocol.reset(this);
 		protocol.chipId = gameInfo.chipID;
 		protocol.gameCode = T1ReadLong((u8*)gameInfo.header.gameCode,0);
+		g_Slot1Comp_MC.connect();
 	}
 
 	virtual u8 auxspi_transaction(int PROCNUM, u8 value)

desmume/src/addons/slot1comp_mc.cpp

@@ -21,6 +21,7 @@
 #include "types.h"
 #include "../MMU.h"
 #include "slot1comp_mc.h"
+#include "NDSSystem.h"
 
 Slot1Comp_MC g_Slot1Comp_MC;
 
@@ -28,8 +29,13 @@ u8 Slot1Comp_MC::auxspi_transaction(int PROCNUM, u8 value)
 {
 	return MMU_new.backupDevice.data_command(value, PROCNUM);
 }
+
 void Slot1Comp_MC::auxspi_reset(int PROCNUM)
 {
 	MMU_new.backupDevice.reset_command();
 }
 
+void Slot1Comp_MC::connect()
+{
+	if(!memcmp(gameInfo.header.gameCode,"AXBJ", 4)) MMU_new.backupDevice.uninitializedValue = 0x00; // Daigassou! Band Brothers DX (JP)
+}

desmume/src/addons/slot1comp_mc.h

@@ -22,6 +22,7 @@ class Slot1Comp_MC
 public:
 	u8 auxspi_transaction(int PROCNUM, u8 value);
 	void auxspi_reset(int PROCNUM);
+	void connect();
 };
 
 extern Slot1Comp_MC g_Slot1Comp_MC;

desmume/src/mc.cpp

@@ -64,13 +64,6 @@
 #define MCLOG(...)
 #endif
 
-//since r2203 this was 0x00.
-//but baby pals proves finally that it should be 0xFF:
-//the game reads its initial sound volumes from uninitialized data, and if it is 0, the game will be silent
-//if it is 0xFF then the game starts with its sound and music at max, as presumably it is supposed to.
-//so in r3303 I finally changed it (no$ appears definitely to initialize to 0xFF)
-static u8 kUninitializedSaveDataValue = 0xFF;
-
 static const char* DESMUME_BACKUP_FOOTER_TXT = "|<--Snip above here to create a raw sav by excluding this DeSmuME savedata footer:";
 static const char* kDesmumeSaveCookie = "|-DESMUME SAVE-|";
 
@@ -219,12 +212,20 @@ BackupDevice::BackupDevice()
 	addr_size = 0;
 	isMovieMode = false;
 
+	//default for most games; will be altered where appropriate
+	//usually 0xFF, but occasionally others. If these exceptions could be related to a particular backup memory type, that would be helpful.
+	//at first we assumed it would be 0x00, but baby pals proved that it should be 0xFF:
+	// the game reads its initial sound volumes from uninitialized data, and if it is 0, the game will be silent
+	// if it is 0xFF then the game starts with its sound and music at max, as presumably it is supposed to.
+	// so in r3303 we finally changed it (no$ appears definitely to initialize to 0xFF)
+	uninitializedValue = 0xFF;
+
 	if (gameInfo.romsize == 0) return;
 
 	char buf[MAX_PATH] = {0};
 	memset(buf, 0, MAX_PATH);
 	path.getpathnoext(path.BATTERY, buf);
-	filename = std::string(buf) + ".dsv";						// DeSmuME memory card
+	filename = std::string(buf) + ".dsv";
 
 	MCLOG("MC: %s\n", filename.c_str());
 
@@ -553,10 +554,6 @@ void BackupDevice::reset_hardware()
 
 	motionInitState = MOTION_INIT_STATE_IDLE;
 	motionFlag = MOTION_FLAG_NONE;
-
-	kUninitializedSaveDataValue = 0xFF;
-
-	if(!memcmp(gameInfo.header.gameCode,"AXBJ", 4)) kUninitializedSaveDataValue = 0x00; // Daigassou! Band Brothers DX (JP)
 }
 
 void BackupDevice::reset()
@@ -876,7 +873,7 @@ u8 BackupDevice::data_command(u8 val, u8 PROCNUM)
 //guarantees that the data buffer has room enough for the specified number of bytes
 void BackupDevice::ensure(u32 addr, EMUFILE_FILE *fpOut)
 {
-	ensure(addr, kUninitializedSaveDataValue, fpOut);
+	ensure(addr, uninitializedValue, fpOut);
 }
 
 void BackupDevice::ensure(u32 addr, u8 val, EMUFILE_FILE *fpOut)
@@ -1322,7 +1319,7 @@ bool BackupDevice::export_raw(const char* filename)
 	if(data.size()>0)
 		fwrite(&data[0],1,size,outf);
 	for(u32 i=size;i<padSize;i++)
-		fputc(kUninitializedSaveDataValue,outf);
+		fputc(uninitializedValue,outf);
 	fclose(outf);
 
 	return true;

desmume/src/mc.h

@@ -140,6 +140,9 @@ public:
 	bool importData(const char *filename, u32 force_size = 0);
 	bool exportData(const char *filename);
 
+	//the value contained in memory when shipped from factory (before user program ever writes to it). more details commented elsewhere.
+	u8 uninitializedValue;
+
 private:
 	EMUFILE_FILE *fpMC;
 	std::string filename;
@@ -155,7 +158,7 @@ private:
 	u32 addr_size, addr_counter;
 	u32 addr;
 	u8 write_protect;
-	
+
 	std::vector<u8> data_autodetect;
 	enum STATE {
 		DETECTING = 0, RUNNING = 1