From 48d548d23b9722637377f07fa923f70a82f13ff4 Mon Sep 17 00:00:00 2001
From: NewRisingSun <8vytz1+dhp372pv94ebg@sharklasers.com>
Date: Tue, 1 Mar 2022 15:54:01 +0100
Subject: [PATCH] Mapper 432: register 0 write also clears register 1. Mapper
 45: Only apply outer bank bits that are unaffected by the inner bank. Mapper
 45: Add PRG /CE-based menu selection.

---
 src/boards/432.c  |  3 ++-
 src/boards/mmc3.c | 40 +++++++++++++++++++++++-----------------
 2 files changed, 25 insertions(+), 18 deletions(-)

diff --git a/src/boards/432.c b/src/boards/432.c
index f774783..5c6db48 100644
--- a/src/boards/432.c
+++ b/src/boards/432.c
@@ -44,6 +44,7 @@ static DECLFR(M432Read) {
 
 static DECLFW(M432Write) {
 	EXPREGS[A & 1] = V;
+	if (~A &1 && ~V &1) EXPREGS[1] =0; /* Writing 0 to register 0 clears register 1 */
 	FixMMC3PRG(MMC3_cmd);
 	FixMMC3CHR(MMC3_cmd);
 }
@@ -51,7 +52,7 @@ static DECLFW(M432Write) {
 static void M432Reset(void) {
 	EXPREGS[0] = 0;
 	EXPREGS[1] = 0;
-	EXPREGS[2] = (EXPREGS[2] +1) & 3;
+	EXPREGS[2]++;
 	MMC3RegReset();
 }
 
diff --git a/src/boards/mmc3.c b/src/boards/mmc3.c
index 35e7762..00f770c 100644
--- a/src/boards/mmc3.c
+++ b/src/boards/mmc3.c
@@ -474,27 +474,33 @@ void Mapper44_Init(CartInfo *info) {
 /* ---------------------------- Mapper 45 ------------------------------- */
 
 static void M45CW(uint32 A, uint8 V) {
-	if (!UNIFchrrama) {
-		uint32 NV = V;
-		if (EXPREGS[2] & 8)
-			NV &= (1 << ((EXPREGS[2] & 7) + 1)) - 1;
-		else
-		if (EXPREGS[2])
-			NV &= 0;	/* hack ;( don't know exactly how it should be */
-		NV |= EXPREGS[0] | ((EXPREGS[2] & 0xF0) << 4);
-		setchr1(A, NV);
-	} else
-		/* setchr8(0); */		/* i don't know what cart need this, but a new one need other lol */
+	if (CHRsize[0] ==8192)
 		setchr1(A, V);
+	else {
+		int chrAND =0xFF >>(~EXPREGS[2] &0xF);
+		int chrOR  =EXPREGS[0] | EXPREGS[2] <<4 &0xF00;
+		setchr1(A, V &chrAND | chrOR &~chrAND);
+	}
+}
+
+static DECLFR(M45ReadOB) {
+	return X.DB;
 }
 
 static void M45PW(uint32 A, uint8 V) {
-	uint32 MV = V & ((EXPREGS[3] & 0x3F) ^ 0x3F);
-	MV |= EXPREGS[1];
-	if(UNIFchrrama)
-		MV |= ((EXPREGS[2] & 0x40) << 2);
-	setprg8(A, MV);
-/*	FCEU_printf("1:%02x 2:%02x 3:%02x A=%04x V=%03x\n",EXPREGS[1],EXPREGS[2],EXPREGS[3],A,MV); */
+	int prgAND =~EXPREGS[3] &0x3F;
+	int prgOR  =EXPREGS[1] | EXPREGS[2] <<2 &0x300;
+	setprg8(A, V &prgAND | prgOR &~prgAND);
+
+	/* Some multicarts select between five different menus by connecting one of the higher address lines to PRG /CE.
+	   The menu code selects between menus by checking which of the higher address lines disables PRG-ROM when set. */
+	if (PRGsize[0] <0x200000 && EXPREGS[5] ==1 && EXPREGS[1] &0x80 ||
+	    PRGsize[0] <0x200000 && EXPREGS[5] ==2 && EXPREGS[2] &0x40 ||
+	    PRGsize[0] <0x100000 && EXPREGS[5] ==3 && EXPREGS[1] &0x40 ||
+	    PRGsize[0] <0x100000 && EXPREGS[5] ==4 && EXPREGS[2] &0x20)
+		SetReadHandler(0x8000, 0xFFFF, M45ReadOB);
+	else
+		SetReadHandler(0x8000, 0xFFFF, CartBR);
 }
 
 static DECLFW(M45Write) {