diff options
Diffstat (limited to 'src/devices/bus/odyssey2/ktaa.cpp')
-rw-r--r-- | src/devices/bus/odyssey2/ktaa.cpp | 59 |
1 files changed, 47 insertions, 12 deletions
diff --git a/src/devices/bus/odyssey2/ktaa.cpp b/src/devices/bus/odyssey2/ktaa.cpp index 4f1fba25153..f14fdf7c113 100644 --- a/src/devices/bus/odyssey2/ktaa.cpp +++ b/src/devices/bus/odyssey2/ktaa.cpp @@ -11,13 +11,33 @@ Bankswitched ROM with page size of 3KB. #include "emu.h" #include "ktaa.h" -DEFINE_DEVICE_TYPE(O2_ROM_KTAA, o2_ktaa_device, "o2_ktaa", "Odyssey 2 Homebrew KTAA") - +namespace { //------------------------------------------------- -// o2_ktaa_device - constructor +// initialization //------------------------------------------------- +class o2_ktaa_device : public device_t, public device_o2_cart_interface +{ +public: + o2_ktaa_device(const machine_config &mconfig, const char *tag, device_t *owner, u32 clock); + +protected: + virtual void device_start() override; + + virtual void cart_init() override; + + virtual u8 read_rom04(offs_t offset) override; + virtual u8 read_rom0c(offs_t offset) override { return read_rom04(offset + 0x800); } + + virtual void write_p1(u8 data) override { m_bank = data & m_bank_mask; } + +private: + u32 m_page_size = 0; + u8 m_bank_mask = 0; + u8 m_bank = 0; +}; + o2_ktaa_device::o2_ktaa_device(const machine_config &mconfig, const char *tag, device_t *owner, u32 clock) : device_t(mconfig, O2_ROM_KTAA, tag, owner, clock), device_o2_cart_interface(mconfig, *this) @@ -30,11 +50,25 @@ void o2_ktaa_device::device_start() void o2_ktaa_device::cart_init() { - u32 size = m_rom.bytes(); - if (size != 0xc00 && size != 0xc00*2 && size != 0xc00*4) - fatalerror("o2_ktaa_device: ROM size must be multiple of 3KB\n"); + bool err = false; + + if (m_rom_size & (m_rom_size - 1)) + { + // freely released binary file is 12KB + err = m_rom_size != 0xc00 && m_rom_size != 0xc00*2 && m_rom_size != 0xc00*4; + m_page_size = 0xc00; + } + else + { + // actual ROM is 16KB(27C128), first 1KB of each 4KB block is empty + err = m_rom_size < 0x1000; + m_page_size = 0x1000; + } - m_bank_mask = (size / 0xc00) - 1; + if (err) + fatalerror("o2_ktaa_device: ROM size must be multiple of 3KB or 4KB\n"); + + m_bank_mask = (m_rom_size / m_page_size) - 1; } @@ -44,10 +78,11 @@ void o2_ktaa_device::cart_init() u8 o2_ktaa_device::read_rom04(offs_t offset) { - return m_rom[offset + m_bank * 0xc00]; + offset += m_page_size - 0xc00; + return m_rom[offset + m_bank * m_page_size]; } -u8 o2_ktaa_device::read_rom0c(offs_t offset) -{ - return m_rom[offset + 0x800 + m_bank * 0xc00]; -} +} // anonymous namespace + + +DEFINE_DEVICE_TYPE_PRIVATE(O2_ROM_KTAA, device_o2_cart_interface, o2_ktaa_device, "o2_ktaa", "Videopac+ KTAA Cartridge") |