/******************************************************************************/
/* Mednafen Sega Saturn Emulation Module                                      */
/******************************************************************************/
/* extram.cpp - Extended RAM(1MiB and 4MiB) 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 "extram.h"

namespace MDFN_IEN_SS
{
static uint16 *ExtRAM; //[0x200000];
static size_t ExtRAM_Mask;
static uint8 Cart_ID;

template <typename T, bool IsWrite>
static MDFN_HOT void ExtRAM_RW_DB(uint32 A, uint16 *DB)
{
	const uint32 mask = (sizeof(T) == 2) ? 0xFFFF : (0xFF << (((A & 1) ^ 1) << 3));
	uint16 *const ptr = (uint16 *)((uint8 *)ExtRAM + (A & ExtRAM_Mask));

	//printf("Barf %zu %d: %08x\n", sizeof(T), IsWrite, A);

	if (IsWrite)
		*ptr = (*ptr & ~mask) | (*DB & mask);
	else
		*DB = *ptr;
}

static MDFN_HOT void CartID_Read_DB(uint32 A, uint16 *DB)
{
	if ((A & ~1) == 0x04FFFFFE)
		*DB = Cart_ID;
}

static MDFN_COLD void Reset(bool powering_up)
{
	if (powering_up)
		memset(ExtRAM, 0, 0x400000); // TODO: Test.
}

void CART_ExtRAM_Init(CartInfo *c, bool R4MiB)
{
	ExtRAM = (uint16 *)alloc_plain(0x400000);
	if (R4MiB)
	{
		Cart_ID = 0x5C;
		ExtRAM_Mask = 0x3FFFFE;
	}
	else
	{
		Cart_ID = 0x5A;
		ExtRAM_Mask = 0x27FFFE;
	}

	SS_SetPhysMemMap(0x02400000, 0x025FFFFF, ExtRAM + (0x000000 / sizeof(uint16)), (R4MiB ? 0x200000 : 0x080000), true);
	SS_SetPhysMemMap(0x02600000, 0x027FFFFF, ExtRAM + (0x200000 / sizeof(uint16)), (R4MiB ? 0x200000 : 0x080000), true);

	c->CS01_SetRW8W16(0x02400000, 0x027FFFFF,
					  ExtRAM_RW_DB<uint16, false>,
					  ExtRAM_RW_DB<uint8, true>,
					  ExtRAM_RW_DB<uint16, true>);

	c->CS01_SetRW8W16(/*0x04FFFFFE*/ 0x04F00000, 0x04FFFFFF, CartID_Read_DB);

	c->Reset = Reset;
	AddMemoryDomain("Ram Cart", ExtRAM, 0x400000, MEMORYAREA_FLAGS_WRITABLE | MEMORYAREA_FLAGS_YUGEENDIAN | MEMORYAREA_FLAGS_WORDSIZE2);
}
}