From 153ca3341eb96e223befaf43c736a90d77e64014 Mon Sep 17 00:00:00 2001
From: MaikelChan <maikelchan88@gmail.com>
Date: Sun, 25 Aug 2024 21:27:21 +0200
Subject: [PATCH 1/2] Detect Perfect Dark GBC Rom, emulating Transfer Pak
 functionality.

---
 port/include/romdata.h |  2 ++
 port/src/main.c        |  1 +
 port/src/romdata.c     | 45 ++++++++++++++++++++++++++++++++++++++++++
 src/game/pak.c         |  8 ++++++++
 src/include/bss.h      |  3 +++
 5 files changed, 59 insertions(+)

diff --git a/port/include/romdata.h b/port/include/romdata.h
index d1d411f1e..d72c411ed 100644
--- a/port/include/romdata.h
+++ b/port/include/romdata.h
@@ -22,4 +22,6 @@ u8 *romdataSegGetData(const char *segName);
 u8 *romdataSegGetDataEnd(const char *segName);
 u32 romdataSegGetSize(const char *segName);
 
+void gbcRomCheck(void);
+
 #endif
diff --git a/port/src/main.c b/port/src/main.c
index e31e090a2..fb225e6f6 100644
--- a/port/src/main.c
+++ b/port/src/main.c
@@ -107,6 +107,7 @@ int main(int argc, const char **argv)
 	inputInit();
 	audioInit();
 	romdataInit();
+	gbcRomCheck();
 
 	gameInit();
 
diff --git a/port/src/romdata.c b/port/src/romdata.c
index effc67e65..20fc55557 100644
--- a/port/src/romdata.c
+++ b/port/src/romdata.c
@@ -11,6 +11,9 @@
 #include "system.h"
 #include "preprocess.h"
 #include "platform.h"
+#ifndef PLATFORM_N64
+#include "bss.h"
+#endif
 
 /**
  * asset files and ROM segments can be replaced by optional external files,
@@ -51,6 +54,9 @@
 
 #define ROMDATA_MAX_FILES 2048
 
+#define GBC_ROM_NAME "pd.gbc"
+#define GBC_ROM_SIZE 4194304
+
 u8 *g_RomFile;
 u32 g_RomFileSize;
 
@@ -386,6 +392,45 @@ s32 romdataInit(void)
 	return 0;
 }
 
+void gbcRomCheck(void)
+{
+	u32 gbcRomSize;
+	u8* gbcRomFile = fsFileLoad(GBC_ROM_NAME, &gbcRomSize);
+
+	if (!gbcRomFile) {
+		return;
+	}
+
+	if (gbcRomSize != GBC_ROM_SIZE) {
+		free(gbcRomFile);
+		return;
+	}
+
+	// ROM title
+
+	if (memcmp(gbcRomFile + 0x134, "PerfDark   VPDE", 15) != 0) {
+		free(gbcRomFile);
+		return;
+	}
+
+	// Licensee code
+
+	if (memcmp(gbcRomFile + 0x144, "4Y", 2) != 0) {
+		free(gbcRomFile);
+		return;
+	}
+
+	// Header and global checksums
+
+	if (gbcRomFile[0x14D] != 0xA1 || gbcRomFile[0x14E] != 0xAD || gbcRomFile[0x14F] != 0x0F) {
+		free(gbcRomFile);
+		return;
+	}
+
+	g_validGbcRomFound = true;
+	free(gbcRomFile);
+}
+
 s32 romdataFileGetSize(s32 fileNum)
 {
 	if (fileNum < 1 || fileNum >= ROMDATA_MAX_FILES) {
diff --git a/src/game/pak.c b/src/game/pak.c
index c58b59de3..09c2fef7d 100644
--- a/src/game/pak.c
+++ b/src/game/pak.c
@@ -329,6 +329,10 @@ u8 g_PaksPlugged = 0;
 bool var80075d14 = true;
 #endif
 
+#ifndef PLATFORM_N64
+bool g_validGbcRomFound = false;
+#endif
+
 u32 pakGetBlockSize(s8 device)
 {
 	return device == SAVEDEVICE_GAMEPAK ? 0x10 : 0x20;
@@ -5982,6 +5986,7 @@ s32 pak0f11e750(s8 device)
 
 bool gbpakIsAnyPerfectDark(void)
 {
+#ifdef PLATFORM_N64
 	s8 i;
 
 	for (i = 0; i < MAX_PLAYERS; i++) {
@@ -5991,6 +5996,9 @@ bool gbpakIsAnyPerfectDark(void)
 	}
 
 	return false;
+#else
+	return g_validGbcRomFound;
+#endif
 }
 
 /**
diff --git a/src/include/bss.h b/src/include/bss.h
index e07a9d931..a322a9a50 100644
--- a/src/include/bss.h
+++ b/src/include/bss.h
@@ -293,5 +293,8 @@ extern struct bossfile g_BossFile;
 extern struct chrdata *g_MpBotChrPtrs[MAX_BOTS];
 extern s32 g_JpnMaxCacheItems;
 extern s32 var8009d370jf;
+#ifndef PLATFORM_N64
+extern bool g_validGbcRomFound;
+#endif
 
 #endif

From 8865130c3594228c7ab61d1f5d9c51fe708f5122 Mon Sep 17 00:00:00 2001
From: MaikelChan <maikelchan88@gmail.com>
Date: Sun, 25 Aug 2024 21:42:54 +0200
Subject: [PATCH 2/2] Added some instructions to README.

---
 README.md | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/README.md b/README.md
index 045a7824a..71a0242d6 100644
--- a/README.md
+++ b/README.md
@@ -33,6 +33,7 @@ There are minor graphics- and gameplay-related issues, and possibly occasional c
 * experimental high framerate support (up to 240 FPS):
   * set `Game.TickRateDivisor` to `0` in `pd.ini` to activate;
   * in practice the game will have issues running faster than ~165 FPS, so use VSync or `Video.FramerateLimit` to cap it.
+* emulate the Transfer Pak functionality the game has on the Nintendo 64 to unlock some cheats automatically.
 
 Currently only 32-bit platforms are supported, namely x86 Windows and Linux.  
 Note that 32-bit binaries will still work on 64-bit versions of those platforms,
@@ -58,6 +59,8 @@ If you want to use a PAL or JPN ROM instead, put them into the `data` directory
 * PAL: ROM name `pd.pal-final.z64`, EXE name `pd.pal.exe`.
 * JPN: ROM name `pd.jpn-final.z64`, EXE name `pd.jpn.exe`.
 
+Optionally, you can also put your Perfect Dark for GameBoy Color ROM named `pd.gbc` in the `data` directory if you want to emulate having the Nintendo 64's Transfer Pak and unlock some cheats automatically.
+
 Additional information can be found in the [wiki](https://github.com/fgsfdsfgs/perfect_dark/wiki).
 
 A GPU supporting OpenGL 3.0 or above is required to run the port.