BizHawk/waterbox/ss/cart/backup.cpp

/******************************************************************************/
/* Mednafen Sega Saturn Emulation Module                                      */
/******************************************************************************/
/* backup.cpp - Backup memory(512KiB) cart emulation
**  Copyright (C) 2016-2017 Mednafen Team
**
** 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 "common.h"
#include "backup.h"

namespace MDFN_IEN_SS
{

static uint8 *ExtBackupRAM;
static bool ExtBackupRAM_Dirty;

// TODO: Check mirroring.
template <typename T, bool IsWrite>
static MDFN_HOT void ExtBackupRAM_RW_DB(uint32 A, uint16 *DB)
{
	uint8 *const ptr = ExtBackupRAM + ((A >> 1) & 0x7FFFF);

	if (IsWrite)
	{
		if (A & 1)
		{
			ExtBackupRAM_Dirty = true;
			*ptr = *DB;
		}
	}
	else
	{
		*DB = (*ptr << 0) | 0xFF00;

		if ((A & ~1) == 0x04FFFFFE)
			*DB = 0x21;
	}
}

static MDFN_COLD bool GetClearNVDirty(void)
{
	bool ret = ExtBackupRAM_Dirty;

	ExtBackupRAM_Dirty = false;

	return ret;
}

static MDFN_COLD void GetNVInfo(const char **ext, void **nv_ptr, uint64 *nv_size)
{
	*ext = "bcr";
	*nv_ptr = ExtBackupRAM;
	*nv_size = 524288;
}

void CART_Backup_Init(CartInfo *c)
{
	static const uint8 init[0x10] = {0x42, 0x61, 0x63, 0x6B, 0x55, 0x70, 0x52, 0x61, 0x6D, 0x20, 0x46, 0x6F, 0x72, 0x6D, 0x61, 0x74};

	ExtBackupRAM = (uint8 *)alloc_plain(524288);
	memset(ExtBackupRAM, 0x00, 524288);
	for (unsigned i = 0; i < 0x200; i += 0x10)
		memcpy(ExtBackupRAM + i, init, 0x10);

	ExtBackupRAM_Dirty = false;

	c->CS01_SetRW8W16(0x04000000, 0x04FFFFFF,
					  ExtBackupRAM_RW_DB<uint16, false>,
					  ExtBackupRAM_RW_DB<uint8, true>,
					  ExtBackupRAM_RW_DB<uint16, true>);

	c->GetClearNVDirty = GetClearNVDirty;
	c->GetNVInfo = GetNVInfo;

	AddMemoryDomain("Backup Cart", ExtBackupRAM, 524288, MEMORYAREA_FLAGS_WRITABLE | MEMORYAREA_FLAGS_SAVERAMMABLE | MEMORYAREA_FLAGS_YUGEENDIAN | MEMORYAREA_FLAGS_WORDSIZE2);
}
}