Add mapper 400.

src/boards/400.c

@@ -0,0 +1,58 @@
+/* FCE Ultra - NES/Famicom Emulator
+ *
+ * Copyright notice for this file:
+ *  Copyright (C) 2025 NewRisingSun
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
+ */
+
+#include "mapinc.h"
+#include "asic_latch.h"
+
+static uint8 reg[4];
+
+static void sync () {
+	setprg16(0x8000, reg[2] &~0x07 | Latch_data &0x07);
+	setprg16(0xC000, reg[3] &~0x07 |             0x07);
+	setchr8(Latch_data >>5);
+	setmirror(reg[3] &0x20? MI_H: MI_V);
+}
+
+static DECLFW (writeReg) {
+	if (!(A &0x7FF)) { /* Exclude 8 Bit Xmas 2008's writes to second APU (also at 7001-7015) */
+		reg[A >>11 &3] = V;
+		sync();
+	}
+}
+
+static void power () {
+	reg[0] = reg[1] = reg[2] = 0;
+	reg[3] = 0x80;
+	Latch_power();
+	SetWriteHandler(0x6000, 0x7FFF, writeReg);
+}
+
+static void reset () {
+	reg[0] = reg[1] = reg[2] = 0;
+	reg[3] = 0x80;
+	Latch_clear();
+}
+
+void Mapper400_Init (CartInfo *info) {
+	Latch_init(info, sync, 0xC000, 0xFFFF, NULL);
+	info->Power = power;
+	info->Reset = reset;
+	AddExState(reg, 4, 0, "REGS");
+}