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// license:BSD-3-Clause
// copyright-holders:Fabio Priuli
/***********************************************************************************************************
NES/Famicom cartridge emulation for Galoob Game Genie PCBs
Here we emulate the following PCBs
* Galoob Game Genie, passthrough hacking cart
***********************************************************************************************************/
#include "emu.h"
#include "ggenie.h"
#include "bus/nes/nes_carts.h"
#ifdef NES_PCB_DEBUG
#define VERBOSE 1
#else
#define VERBOSE 0
#endif
#define LOG_MMC(x) do { if (VERBOSE) logerror x; } while (0)
//-------------------------------------------------
// constructor
//-------------------------------------------------
DEFINE_DEVICE_TYPE(NES_GGENIE, nes_ggenie_device, "nes_ggenie", "NES Cart Game Genie PCB")
nes_ggenie_device::nes_ggenie_device(const machine_config &mconfig, const char *tag, device_t *owner, uint32_t clock)
: nes_nrom_device(mconfig, NES_GGENIE, tag, owner, clock)
, m_ggslot(*this, "gg_slot")
, m_gg_bypass(0)
{
}
void nes_ggenie_device::device_start()
{
common_start();
save_item(NAME(m_gg_bypass));
}
void nes_ggenie_device::pcb_start(running_machine &machine, uint8_t *ciram_ptr, bool cart_mounted)
{
device_nes_cart_interface::pcb_start(machine, ciram_ptr, cart_mounted);
if (m_ggslot->m_cart)
m_ggslot->pcb_start(m_ciram);
}
void nes_ggenie_device::pcb_reset()
{
m_chr_source = m_vrom_chunks ? CHRROM : CHRRAM;
prg32(0);
chr8(0, m_chr_source);
set_nt_mirroring(PPU_MIRROR_LOW);
m_gg_bypass = 0;
if (m_ggslot->m_cart)
m_ggslot->m_cart->pcb_reset();
}
/*-------------------------------------------------
mapper specific handlers
-------------------------------------------------*/
/*-------------------------------------------------
Game Genie board emulation
-------------------------------------------------*/
void nes_ggenie_device::write_h(offs_t offset, uint8_t data)
{
// LOG_MMC(("axrom write_h, offset: %04x, data: %02x\n", offset, data));
if (!m_gg_bypass)
{
// From blargg: Codes are written to $8001-800C, starting at $800C and going down to $8001.
// Next, two values are written to $8000. The first specify the kind of codes which have
// been inserted, the second write to $8000 is always zero (all 8 bits).
// This probably disables the boot ROM (the code is executing from RAM at this point).
// Once done, the code jumps to ($FFFC) to begin the game.
// All 12 bytes from $8001-800C are written regardless of how many codes are inserted.
// The value written to $8000 is the only clue as to what codes are actually valid and which
// ones have compare values.
if (offset)
{
int code;
offset -= 1;
code = (offset & 0xc) >> 2;
if (code == 3)
return; // how did we end up here? the GG is not expected to write to $800d-800f!
switch (offset & 3)
{
case 0:
m_gg_addr[code] |= (data & 0x7f) << 8;
break;
case 1:
m_gg_addr[code] = data;
break;
case 2:
m_gg_comp[code] = data;
break;
case 3:
m_gg_repl[code] = data;
break;
}
return;
}
if (offset == 0 && data == 0)
{
m_gg_bypass = 1;
reset_cpu();
}
else
{
// bit 0 is always set (GG enable?)
m_gg_is_comp[0] = BIT(data, 1);
m_gg_is_comp[1] = BIT(data, 2);
m_gg_is_comp[2] = BIT(data, 3);
m_gg_disable[0] = BIT(data, 4);
m_gg_disable[1] = BIT(data, 5);
m_gg_disable[2] = BIT(data, 6);
// bit 7 is always clear
logerror("Game Genie Summary:\n");
for (int i = 0; i < 3; i++)
{
logerror("Code %d: %s\n", i, m_gg_disable[i] ? "No" : "Yes");
if (!m_gg_disable[i])
{
logerror("\tAddr: 0x%X\n", m_gg_addr[i]);
logerror("\tValue: 0x%X\n", m_gg_repl[i]);
if (m_gg_is_comp[i])
logerror("\t if equals: 0x%X\n", m_gg_comp[i]);
}
}
}
}
else
m_ggslot->write_h(offset, data);
}
void nes_ggenie_device::write_m(offs_t offset, uint8_t data)
{
if (m_gg_bypass && m_ggslot)
m_ggslot->write_m(offset, data);
}
void nes_ggenie_device::write_l(offs_t offset, uint8_t data)
{
if (m_gg_bypass && m_ggslot)
m_ggslot->write_l(offset, data);
}
uint8_t nes_ggenie_device::read_h(offs_t offset)
{
if (m_gg_bypass && m_ggslot->m_cart)
{
uint8_t rom_value = m_ggslot->m_cart->hi_access_rom(offset);
// check if GG code has to act on this address
for (int i = 0; i < 3; i++)
{
if (!m_gg_disable[i] && offset == m_gg_addr[i])
{
if (!m_gg_is_comp[i] || (m_gg_is_comp[i] && m_gg_comp[i] == rom_value))
return m_gg_repl[i];
}
}
return rom_value;
}
return hi_access_rom(offset);
}
uint8_t nes_ggenie_device::read_m(offs_t offset)
{
if (m_gg_bypass && m_ggslot->m_cart)
return m_ggslot->m_cart->read_m(offset);
return 0xff;
}
uint8_t nes_ggenie_device::read_l(offs_t offset)
{
if (m_gg_bypass && m_ggslot->m_cart)
return m_ggslot->m_cart->read_l(offset);
return 0xff;
}
void nes_ggenie_device::chr_w(offs_t offset, uint8_t data)
{
int bank = offset >> 10;
if (m_gg_bypass && m_ggslot->m_cart)
{
m_ggslot->m_cart->chr_w(offset, data);
return;
}
if (m_chr_src[bank] == CHRRAM)
m_chr_access[bank][offset & 0x3ff] = data;
}
uint8_t nes_ggenie_device::chr_r(offs_t offset)
{
int bank = offset >> 10;
if (m_gg_bypass && m_ggslot->m_cart)
return m_ggslot->m_cart->chr_r(offset);
return m_chr_access[bank][offset & 0x3ff];
}
void nes_ggenie_device::nt_w(offs_t offset, uint8_t data)
{
int page = ((offset & 0xc00) >> 10);
if (m_gg_bypass && m_ggslot->m_cart)
{
m_ggslot->m_cart->nt_w(offset, data);
return;
}
if (!m_nt_writable[page])
return;
m_nt_access[page][offset & 0x3ff] = data;
}
uint8_t nes_ggenie_device::nt_r(offs_t offset)
{
int page = ((offset & 0xc00) >> 10);
if (m_gg_bypass && m_ggslot->m_cart)
return m_ggslot->m_cart->nt_r(offset);
return m_nt_access[page][offset & 0x3ff];
}
//-------------------------------------------------
// device_add_mconfig - add device configuration
//-------------------------------------------------
void nes_ggenie_device::device_add_mconfig(machine_config &config)
{
NES_CART_SLOT(config, "gg_slot", DERIVED_CLOCK(1, 1), nes_cart, nullptr).set_must_be_loaded(false);
}
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