// license:BSD-3-Clause // copyright-holders:etabeta /*********************************************************************************************************** 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 //------------------------------------------------- const device_type GENERIC_ROM_PLAIN = &device_creator; const device_type GENERIC_ROM_LINEAR = &device_creator; const device_type GENERIC_ROMRAM_PLAIN = &device_creator; generic_rom_device::generic_rom_device(const machine_config &mconfig, device_type type, const char *name, const char *tag, device_t *owner, UINT32 clock, const char *shortname, const char *source) : device_t(mconfig, type, name, tag, owner, clock, shortname, source), device_generic_cart_interface(mconfig, *this) { } generic_rom_plain_device::generic_rom_plain_device(const machine_config &mconfig, device_type type, const char *name, const char *tag, device_t *owner, UINT32 clock, const char *shortname, const char *source) : generic_rom_device(mconfig, type, name, tag, owner, clock, shortname, source) { } generic_rom_plain_device::generic_rom_plain_device(const machine_config &mconfig, const char *tag, device_t *owner, UINT32 clock) : generic_rom_device(mconfig, GENERIC_ROM_PLAIN, "Generic ROM (plain mapping)", tag, owner, clock, "generic_rom_plain", __FILE__) { } generic_rom_linear_device::generic_rom_linear_device(const machine_config &mconfig, const char *tag, device_t *owner, UINT32 clock) : generic_rom_device(mconfig, GENERIC_ROM_LINEAR, "Generic ROM (linear mapping)", tag, owner, clock, "generic_rom_linear", __FILE__) { } generic_romram_plain_device::generic_romram_plain_device(const machine_config &mconfig, const char *tag, device_t *owner, UINT32 clock) : generic_rom_plain_device(mconfig, GENERIC_ROMRAM_PLAIN, "Generic ROM + RAM (plain mapping)", tag, owner, clock, "generic_romram_plain", __FILE__) { } /*------------------------------------------------- mapper specific handlers -------------------------------------------------*/ READ8_MEMBER(generic_rom_plain_device::read_rom) { if (offset < m_rom_size) return m_rom[offset]; else return 0xff; } READ16_MEMBER(generic_rom_plain_device::read16_rom) { UINT16 *ROM = (UINT16 *)m_rom; if (offset < m_rom_size/2) return ROM[offset]; else return 0xffff; } READ32_MEMBER(generic_rom_plain_device::read32_rom) { UINT32 *ROM = (UINT32 *)m_rom; if (offset < m_rom_size/4) return ROM[offset]; else return 0xffffffff; } READ8_MEMBER(generic_rom_linear_device::read_rom) { return m_rom[offset % m_rom_size]; } READ16_MEMBER(generic_rom_linear_device::read16_rom) { UINT16 *ROM = (UINT16 *)m_rom; return ROM[offset % (m_rom_size/2)]; } READ32_MEMBER(generic_rom_linear_device::read32_rom) { UINT32 *ROM = (UINT32 *)m_rom; return ROM[offset % (m_rom_size/4)]; } READ8_MEMBER(generic_romram_plain_device::read_ram) { if (offset < m_ram.bytes()) return m_ram[offset]; else return 0xff; } WRITE8_MEMBER(generic_romram_plain_device::write_ram) { if (offset < m_ram.bytes()) m_ram[offset] = data; }