From 3d4765ad74b4b14127d5c56355a9563cdae7333b Mon Sep 17 00:00:00 2001
From: retro-wertz <retro-wertz@users.noreply.github.com>
Date: Tue, 17 Oct 2017 11:57:21 +0800
Subject: [PATCH] Mapper57: fix mirroring

---
 src/boards/57.c | 35 +++++++++++++++--------------------
 1 file changed, 15 insertions(+), 20 deletions(-)

diff --git a/src/boards/57.c b/src/boards/57.c
index bb93c37..df79d44 100644
--- a/src/boards/57.c
+++ b/src/boards/57.c
@@ -21,47 +21,42 @@
 
 #include "mapinc.h"
 
-static uint8 prg_reg;
-static uint8 chr_reg;
+static uint8 regs[2];
 static uint8 hrd_flag;
 
 static SFORMAT StateRegs[] =
 {
 	{ &hrd_flag, 1, "DPSW" },
-	{ &prg_reg, 1, "PRG" },
-	{ &chr_reg, 1, "CHR" },
+	{ regs, 2, "REGS" },
 	{ 0 }
 };
 
 static void Sync(void) {
-	if (prg_reg & 0x10)
-		setprg32(0x8000, (prg_reg >> 6) & 3);
+	if (regs[1] & 0x10)
+		setprg32(0x8000, (regs[1] >> 6) & 3);
 	else {
-		setprg16(0x8000, (prg_reg >> 5) & 7);
-		setprg16(0xC000, (prg_reg >> 5) & 7);
+		setprg16(0x8000, (regs[1] >> 5) & 7);
+		setprg16(0xC000, (regs[1] >> 5) & 7);
 	}
-	/* Mirroring (0=Vert, 1=Horz)
-	 * https://wiki.nesdev.com/w/index.php/INES_Mapper_057
-	 */
-	setmirror((prg_reg & 8) ? MI_H : MI_V);
-	setchr8((chr_reg & 7) | (prg_reg & 7) | ((chr_reg & 0x40) >> 3));
+	setmirror((regs[1] & 8) >> 3 ^ 1);
+	setchr8((regs[0] & 7) | (regs[1] & 7) | ((regs[0] & 0x40) >> 3));
 }
 
+#if 0
 static DECLFR(M57Read) {
 	return hrd_flag;
 }
+#endif
 
 static DECLFW(M57Write) {
-	if ((A & 0x8800) == 0x8800)
-		prg_reg = V;
-	else
-		chr_reg = V;
-	Sync();
+	switch (A & 0x8800) {
+		case 0x8000: regs[0] = V; Sync(); break;
+		case 0x8800: regs[1] = V; Sync(); break;
+	}
 }
 
 static void M57Power(void) {
-	prg_reg = 0;
-	chr_reg = 0;
+	regs[1] = regs[0] = 0;
 	hrd_flag = 0;
 	SetReadHandler(0x8000, 0xFFFF, CartBR);
 	SetWriteHandler(0x8000, 0xFFFF, M57Write);