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Genesis-Plus-GX/core/cart_hw/areplay.c

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/****************************************************************************
* Genesis Plus
* Action Replay / Pro Action Replay hardware support
*
* Copyright (C) 2009-2021 Eke-Eke (Genesis Plus GX)
*
* Redistribution and use of this code or any derivative works are permitted
* provided that the following conditions are met:
*
* - Redistributions may not be sold, nor may they be used in a commercial
* product or activity.
*
* - Redistributions that are modified from the original source must include the
* complete source code, including the source code for all components used by a
* binary built from the modified sources. However, as a special exception, the
* source code distributed need not include anything that is normally distributed
* (in either source or binary form) with the major components (compiler, kernel,
* and so on) of the operating system on which the executable runs, unless that
* component itself accompanies the executable.
*
* - Redistributions must reproduce the above copyright notice, this list of
* conditions and the following disclaimer in the documentation and/or other
* materials provided with the distribution.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
* AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
* LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
* CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
* SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
* INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
* CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
* POSSIBILITY OF SUCH DAMAGE.
*
****************************************************************************************/
#include "shared.h"
#define TYPE_PRO1 0x12
#define TYPE_PRO2 0x22
static struct
{
uint8 enabled;
uint8 status;
uint8 ram[0x10000];
uint16 regs[13];
uint16 old[4];
uint16 data[4];
uint32 addr[4];
} action_replay;
static void ar_write_regs(uint32 address, uint32 data);
static void ar2_write_reg(uint32 address, uint32 data);
static void ar_write_ram_8(uint32 address, uint32 data);
void areplay_init(void)
{
action_replay.enabled = action_replay.status = 0;
/* try to load Action Replay ROM file (max. 64KB) */
if (load_archive(AR_ROM, cart.lockrom, 0x10000, NULL) > 0)
{
/* detect Action Replay board type */
if (!memcmp(cart.lockrom + 0x120, "ACTION REPLAY ", 16))
{
/* normal Action Replay (32KB ROM) */
action_replay.enabled = TYPE_AR;
/* $0000-$7fff mirrored into $8000-$ffff */
memcpy(cart.lockrom + 0x8000, cart.lockrom, 0x8000);
/* internal registers mapped at $010000-$01ffff */
m68k.memory_map[0x01].write16 = ar_write_regs;
}
else
{
/* Read stack pointer MSB */
uint8 sp = cart.lockrom[0x01];
/* Detect board version */
if ((sp == 0x42) && !memcmp(cart.lockrom + 0x120, "ACTION REPLAY 2 ", 16))
{
/* PRO Action Replay (2x32KB ROM) */
action_replay.enabled = TYPE_PRO1;
/* internal registers mapped at $010000-$01ffff */
m68k.memory_map[0x01].write16 = ar_write_regs;
}
else if ((sp == 0x60) && !memcmp(cart.lockrom + 0x3c6, "ACTION REPLAY II", 16))
{
/* PRO Action Replay 2 (2x32KB ROM) */
action_replay.enabled = TYPE_PRO2;
/* internal register mapped at $100000-$10ffff */
m68k.memory_map[0x10].write16 = ar2_write_reg;
}
/* internal RAM (64KB), mapped at $420000-$42ffff or $600000-$60ffff */
if (action_replay.enabled)
{
m68k.memory_map[sp].base = action_replay.ram;
m68k.memory_map[sp].read8 = NULL;
m68k.memory_map[sp].read16 = NULL;
m68k.memory_map[sp].write8 = ar_write_ram_8;
m68k.memory_map[sp].write16 = NULL;
}
}
#ifdef LSB_FIRST
if (action_replay.enabled)
{
int i;
for (i= 0; i<0x10000; i+=2)
{
/* Byteswap ROM */
uint8 temp = cart.lockrom[i];
cart.lockrom[i] = cart.lockrom[i+1];
cart.lockrom[i+1] = temp;
}
}
#endif
}
}
void areplay_shutdown(void)
{
/* clear existing patches */
areplay_set_status(AR_SWITCH_OFF);
/* disable device by default */
action_replay.enabled = 0;
}
void areplay_reset(int hard)
{
if (action_replay.enabled)
{
if (hard || (action_replay.status == AR_SWITCH_TRAINER))
{
/* reset internal registers */
memset(action_replay.regs, 0, sizeof(action_replay.regs));
memset(action_replay.old, 0, sizeof(action_replay.old));
memset(action_replay.data, 0, sizeof(action_replay.data));
memset(action_replay.addr, 0, sizeof(action_replay.addr));
/* by default, internal ROM is mapped at $000000-$00FFFF */
m68k.memory_map[0].base = cart.lockrom;
/* reset internal RAM on power-on */
if (hard)
{
memset(action_replay.ram,0xff,0x10000);
}
}
}
}
int areplay_get_status(void)
{
if (action_replay.enabled)
{
return action_replay.status;
}
return -1;
}
void areplay_set_status(int status)
{
if (action_replay.enabled)
{
/* no Trainer mode for normal Action Replay */
if ((action_replay.enabled == TYPE_AR) && (status == AR_SWITCH_TRAINER))
{
status = AR_SWITCH_OFF;
}
/* check status changes */
switch (status)
{
case AR_SWITCH_OFF:
case AR_SWITCH_TRAINER:
{
/* check that patches were previously enabled */
if (action_replay.status == AR_SWITCH_ON)
{
/* restore original data */
*(uint16 *)(cart.rom + action_replay.addr[0]) = action_replay.old[0];
*(uint16 *)(cart.rom + action_replay.addr[1]) = action_replay.old[1];
*(uint16 *)(cart.rom + action_replay.addr[2]) = action_replay.old[2];
*(uint16 *)(cart.rom + action_replay.addr[3]) = action_replay.old[3];
}
break;
}
case AR_SWITCH_ON:
{
/* check that patches were previously disabled */
if (action_replay.status != AR_SWITCH_ON)
{
/* decode patch data */
action_replay.data[0] = action_replay.regs[0];
action_replay.data[1] = action_replay.regs[4];
action_replay.data[2] = action_replay.regs[7];
action_replay.data[3] = action_replay.regs[10];
/* decode patch address ($000000-$7fffff) */
action_replay.addr[0] = (action_replay.regs[1] | ((action_replay.regs[2] & 0x3f00) << 8)) << 1;
action_replay.addr[1] = (action_replay.regs[5] | ((action_replay.regs[6] & 0x3f00) << 8)) << 1;
action_replay.addr[2] = (action_replay.regs[8] | ((action_replay.regs[9] & 0x3f00) << 8)) << 1;
action_replay.addr[3] = (action_replay.regs[11] | ((action_replay.regs[12] & 0x3f00) << 8)) << 1;
/* save original data */
action_replay.old[0] = *(uint16 *)(cart.rom + action_replay.addr[0]);
action_replay.old[1] = *(uint16 *)(cart.rom + action_replay.addr[1]);
action_replay.old[2] = *(uint16 *)(cart.rom + action_replay.addr[2]);
action_replay.old[3] = *(uint16 *)(cart.rom + action_replay.addr[3]);
/* patch new data */
*(uint16 *)(cart.rom + action_replay.addr[0]) = action_replay.data[0];
*(uint16 *)(cart.rom + action_replay.addr[1]) = action_replay.data[1];
*(uint16 *)(cart.rom + action_replay.addr[2]) = action_replay.data[2];
*(uint16 *)(cart.rom + action_replay.addr[3]) = action_replay.data[3];
}
break;
}
default:
{
return;
}
}
/* update status */
action_replay.status = status;
}
}
static void ar_write_regs(uint32 address, uint32 data)
{
/* register offset */
int offset = (address & 0xffff) >> 1;
if (offset > 12)
{
m68k_unused_16_w(address,data);
return;
}
/* update internal register */
action_replay.regs[offset] = data;
/* MODE register */
if (action_replay.regs[3] == 0xffff)
{
/* check switch status */
if (action_replay.status == AR_SWITCH_ON)
{
/* reset existing patches */
areplay_set_status(AR_SWITCH_OFF);
areplay_set_status(AR_SWITCH_ON);
}
/* enable Cartridge ROM */
m68k.memory_map[0].base = cart.rom;
}
}
static void ar2_write_reg(uint32 address, uint32 data)
{
/* enable Cartridge ROM */
if (((address & 0xff) == 0x78) && (data == 0xffff))
{
m68k.memory_map[0].base = cart.rom;
}
}
static void ar_write_ram_8(uint32 address, uint32 data)
{
/* byte writes are handled as word writes, with LSB duplicated in MSB (/LWR is not used) */
*(uint16 *)(action_replay.ram + (address & 0xfffe)) = (data | (data << 8));
}
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