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// license:BSD-3-Clause
// copyright-holders:Fabio Priuli
/***********************************************************************************************************
Generic ROM emulation (for carts and ROM sockets)
This offers generic access to a ROM
generic_rom_plain : returns 0xff when the system reads beyond the end of the ROM
generic_rom_linear : maps linearly the ROM in the accessed area (i.e., read offset is masked with (ROM size - 1) )
generic_romram_plain : allows support for carts always containing ROM + RAM (e.g. X07)
TODO:
- possibly support linear mapping when non-power of 2 ROMs are mapped
***********************************************************************************************************/
#include "emu.h"
#include "rom.h"
//-------------------------------------------------
// constructor
//-------------------------------------------------
DEFINE_DEVICE_TYPE(GENERIC_ROM_PLAIN, generic_rom_plain_device, "generic_rom_plain", "Generic ROM (plain mapping)")
DEFINE_DEVICE_TYPE(GENERIC_ROM_LINEAR, generic_rom_linear_device, "generic_rom_linear", "Generic ROM (linear mapping)")
DEFINE_DEVICE_TYPE(GENERIC_ROMRAM_PLAIN, generic_romram_plain_device, "generic_romram_plain", "Generic ROM + RAM (plain mapping)")
generic_rom_device::generic_rom_device(const machine_config &mconfig, device_type type, const char *tag, device_t *owner, uint32_t clock)
: device_t(mconfig, type, tag, owner, clock), device_generic_cart_interface(mconfig, *this)
{
}
generic_rom_plain_device::generic_rom_plain_device(const machine_config &mconfig, device_type type, const char *tag, device_t *owner, uint32_t clock)
: generic_rom_device(mconfig, type, tag, owner, clock)
{
}
generic_rom_plain_device::generic_rom_plain_device(const machine_config &mconfig, const char *tag, device_t *owner, uint32_t clock)
: generic_rom_plain_device(mconfig, GENERIC_ROM_PLAIN, tag, owner, clock)
{
}
generic_rom_linear_device::generic_rom_linear_device(const machine_config &mconfig, const char *tag, device_t *owner, uint32_t clock)
: generic_rom_device(mconfig, GENERIC_ROM_LINEAR, tag, owner, clock)
{
}
generic_romram_plain_device::generic_romram_plain_device(const machine_config &mconfig, const char *tag, device_t *owner, uint32_t clock)
: generic_rom_plain_device(mconfig, GENERIC_ROMRAM_PLAIN, tag, owner, clock)
{
}
/*-------------------------------------------------
mapper specific handlers
-------------------------------------------------*/
uint8_t generic_rom_plain_device::read_rom(offs_t offset)
{
if (offset < m_rom_size)
return m_rom[offset];
else
return 0xff;
}
uint16_t generic_rom_plain_device::read16_rom(offs_t offset, uint16_t mem_mask)
{
uint16_t *ROM = (uint16_t *)m_rom;
if (offset < m_rom_size/2)
return ROM[offset];
else
return 0xffff;
}
uint32_t generic_rom_plain_device::read32_rom(offs_t offset, uint32_t mem_mask)
{
uint32_t *ROM = (uint32_t *)m_rom;
if (offset < m_rom_size/4)
return ROM[offset];
else
return 0xffffffff;
}
uint8_t generic_rom_linear_device::read_rom(offs_t offset)
{
return m_rom[offset % m_rom_size];
}
uint16_t generic_rom_linear_device::read16_rom(offs_t offset, uint16_t mem_mask)
{
uint16_t *ROM = (uint16_t *)m_rom;
return ROM[offset % (m_rom_size/2)];
}
uint32_t generic_rom_linear_device::read32_rom(offs_t offset, uint32_t mem_mask)
{
uint32_t *ROM = (uint32_t *)m_rom;
return ROM[offset % (m_rom_size/4)];
}
uint8_t generic_romram_plain_device::read_ram(offs_t offset)
{
if (offset < m_ram.size())
return m_ram[offset];
else
return 0xff;
}
void generic_romram_plain_device::write_ram(offs_t offset, uint8_t data)
{
if (offset < m_ram.size())
m_ram[offset] = data;
}
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