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// license:BSD-3-Clause
// copyright-holders:Wilbert Pol
#include "emu.h"
#include "nomapper.h"
namespace {
class msx_cart_nomapper_device : public device_t, public msx_cart_interface
{
public:
msx_cart_nomapper_device(const machine_config &mconfig, const char *tag, device_t *owner, uint32_t clock)
: device_t(mconfig, MSX_CART_NOMAPPER, tag, owner, clock)
, msx_cart_interface(mconfig, *this)
, m_start_address(0)
, m_end_address(0)
{ }
// device_t implementation
virtual void device_start() override { }
virtual std::error_condition initialize_cartridge(std::string &message) override;
private:
uint32_t m_start_address;
uint32_t m_end_address;
void install_memory();
};
void msx_cart_nomapper_device::install_memory()
{
u32 start_address = m_start_address;
u32 rom_offset = 0;
if (m_start_address != 0x0000 && m_start_address != 0x4000 && m_start_address != 0x8000 && m_start_address != 0xc000)
{
fatalerror("nomapper: Unsupported start address %04x\n", m_start_address);
}
for (int i = 0; i < 4; i++)
{
if (start_address < (i + 1) * 0x4000 && start_address < m_end_address)
{
if (page(i))
{
page(i)->install_rom(start_address, std::min<uint32_t>(start_address + 0x3fff, m_end_address - 1), cart_rom_region()->base() + rom_offset);
}
rom_offset += 0x4000;
start_address += 0x4000;
}
}
}
std::error_condition msx_cart_nomapper_device::initialize_cartridge(std::string &message)
{
if (!cart_rom_region())
{
message = "msx_cart_nomapper_device: Required region 'rom' was not found.";
return image_error::INTERNAL;
}
const u32 size = cart_rom_region()->bytes();
u8 *rom = cart_rom_region()->base();
// 64KB images fill all pages.
if (size == 0x10000)
{
m_start_address = 0;
}
else if (is_loaded_through_softlist())
{
const char *start_page_str = get_feature("start_page");
if (!start_page_str)
{
message = "msx_cart_nomapper_device: Feature 'start_page' was not found.";
return image_error::BADSOFTWARE;
}
u32 start_page = strtol(start_page_str, nullptr, 0);
if (start_page > 2)
{
message = "msx_cart_nomapper_device: Invalid value for 'start_page', allowed values are 0, 1, and 2";
return image_error::BADSOFTWARE;
}
m_start_address = start_page * 0x4000;
}
else
{
// Try to guess the start address from the rom contents.
// determine start address, default to 0x4000
m_start_address = 0x4000;
switch (size)
{
// 8KB/16KB
case 0x2000: case 0x4000:
{
uint16_t start = rom[3] << 8 | rom[2];
// start address of $0000: call address in the $4000 region: $4000, else $8000
if (start == 0)
{
if ((rom[5] & 0xc0) == 0x40)
m_start_address = 0x4000;
else
m_start_address = 0x8000;
}
// start address in the $8000 region: $8000, else default
else if ((start & 0xc000) == 0x8000)
m_start_address = 0x8000;
break;
}
// 32KB
case 0x8000:
// take default, check when no "AB" at $0000, but "AB" at $4000
if (rom[0] != 'A' && rom[1] != 'B' && rom[0x4000] == 'A' && rom[0x4001] == 'B')
{
uint16_t start = rom[0x4003] << 8 | rom[0x4002];
// start address of $0000 and call address in the $4000 region, or start address outside the $8000 region: $0000, else default
if ((start == 0 && (rom[0x4005] & 0xc0) == 0x40) || start < 0x8000 || start >= 0xc000)
m_start_address = 0;
}
break;
// 48KB
case 0xc000:
// "AB" at $0000, but no "AB" at $4000, not "AB": $0000
if (rom[0] == 'A' && rom[1] == 'B' && rom[0x4000] != 'A' && rom[0x4001] != 'B')
m_start_address = 0x4000;
else
m_start_address = 0;
break;
}
}
m_end_address = std::min<u32>(m_start_address + size, 0x10000);
install_memory();
return std::error_condition();
}
} // anonymous namespace
DEFINE_DEVICE_TYPE_PRIVATE(MSX_CART_NOMAPPER, msx_cart_interface, msx_cart_nomapper_device, "msx_cart_nomapper", "MSX Cartridge - ROM")
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