From 52281a4474e9dccce50248f8e73e8838f070d4aa Mon Sep 17 00:00:00 2001
From: retro-wertz <retro-wertz@users.noreply.github.com>
Date: Sun, 1 Oct 2017 23:39:19 +0800
Subject: [PATCH] Update Ganbare Goemon Gaiden 2 to use Mapper21 based on
 sources

---
 src/boards/vrc2and4.c | 31 +++++++++++++++----------------
 src/ines-correct.h    |  4 ++--
 2 files changed, 17 insertions(+), 18 deletions(-)

diff --git a/src/boards/vrc2and4.c b/src/boards/vrc2and4.c
index 499bd59..87c1435 100644
--- a/src/boards/vrc2and4.c
+++ b/src/boards/vrc2and4.c
@@ -131,9 +131,7 @@ static DECLFW(VRC24Write) {
 }
 
 static DECLFW(M21Write) {
-	A = (A & 0xF000) | ((A >> 1) & 0x3);						/* Ganbare Goemon Gaiden 2 - Tenka no Zaihou (J) [!] isn't mapper 21 actually,
-																 * it's mapper 23 by wirings
-																 */
+	A = (A & 0xF000) | ((A >> 1) & 0x3) | ((A >> 6) & 0x3);		/* Ganbare Goemon Gaiden 2 - Tenka no Zaihou (J) [!] is Mapper 21*/
 	VRC24Write(A, V);
 }
 
@@ -154,14 +152,18 @@ static DECLFW(M22Write) {
 }
 
 static DECLFW(M23Write) {
-	A |= ((A >> 2) & 0x3) | ((A >> 4) & 0x3) | ((A >> 6) & 0x3);/* actually there is many-in-one mapper source, some pirate or
-																 * licensed games use various address bits for registers
-																 */
+	A |= ((A >> 2) & 0x3) | ((A >> 4) & 0x3);	/* actually there is many-in-one mapper source, some pirate or
+												 * licensed games use various address bits for registers
+												 */
 	VRC24Write(A, V);
 }
 
 static void M21Power(void) {
 	Sync();
+	setprg8r(0x10, 0x6000, 0);
+	SetReadHandler(0x6000, 0x7FFF, CartBR);
+	SetWriteHandler(0x6000, 0x7FFF, CartBW);
+	FCEU_CheatAddRAM(WRAMSIZE >> 10, 0x6000, WRAM);
 	SetReadHandler(0x8000, 0xFFFF, CartBR);
 	SetWriteHandler(0x8000, 0xFFFF, M21Write);
 }
@@ -223,16 +225,6 @@ static void VRC24Close(void) {
 	WRAM = NULL;
 }
 
-void Mapper21_Init(CartInfo *info) {
-	isPirate = 0;
-	is22 = 0;
-	info->Power = M21Power;
-	MapIRQHook = VRC24IRQHook;
-	GameStateRestore = StateRestore;
-
-	AddExState(&StateRegs, ~0, 0, 0);
-}
-
 void Mapper22_Init(CartInfo *info) {
 	isPirate = 0;
 	is22 = 1;
@@ -260,6 +252,13 @@ void VRC24_Init(CartInfo *info) {
 	AddExState(&StateRegs, ~0, 0, 0);
 }
 
+void Mapper21_Init(CartInfo *info) {
+	isPirate = 0;
+	is22 = 0;
+	info->Power = M21Power;
+	VRC24_Init(info);
+}
+
 void Mapper23_Init(CartInfo *info) {
 	isPirate = 0;
 	is22 = 0;
diff --git a/src/ines-correct.h b/src/ines-correct.h
index c421645..98ceca3 100644
--- a/src/ines-correct.h
+++ b/src/ines-correct.h
@@ -105,7 +105,7 @@
 	{0x6e68e31a,	 16,		8},	/* Dragon Ball 3*/
 	{0x33b899c9,	 16,	   -1},	/* Dragon Ball - Dai Maou Fukkatsu (J) [!] */
 	{0xa262a81f,	 16,	   -1},	/* Rokudenashi Blues (J) */
-	{0x286fcd20,	 23,	   -1},	/* Ganbare Goemon Gaiden 2 - Tenka no Zaihou (J) [!] */
+	{0x286fcd20,	 21,	   -1},	/* Ganbare Goemon Gaiden 2 - Tenka no Zaihou (J) [!] */
 	{0xe4a291ce,	 23,	   -1},	/* World Hero (Unl) [!] */
 	{0x51e9cd33,	 23,	   -1},	/* World Hero (Unl) [b1] */
 	{0x105dd586,	 27,	   -1},	/* Mi Hun Che variations... */
@@ -275,7 +275,7 @@
 	{0x276237b3,	206,		0},	/* Karnov */
 	{0xa5e6baf9,	206,		1},	/* Dragon Slayer 4 - Drasle Family (Japan) */
 	{0x4f2f1846,	206,		1},	/* Famista '89 - Kaimaku Han!! (J) */
-	{0x22d6d5bd,	206,		1},	/* Jikuu Yuuden - Debias (J) */	
+	{0x22d6d5bd,	206,		1},	/* Jikuu Yuuden - Debias (J) */
 	{0x9d21fe96,	206,		1},	/* Lupin Sansei - Pandora no Isan (Japan) */
 	{0x96dfc776,	206,		1},	/* R.B.I. Baseball 2 (USA) (Unl) */
 	{0xfd63e7ac,	206,		1},	/* R.B.I. Baseball 3 (USA) (Unl) */