// license:BSD-3-Clause // copyright-holders:Wilbert Pol #include "emu.h" #include "holy_quran.h" const device_type MSX_CART_HOLY_QURAN = &device_creator; msx_cart_holy_quran::msx_cart_holy_quran(const machine_config &mconfig, const char *tag, device_t *owner, UINT32 clock) : device_t(mconfig, MSX_CART_HOLY_QURAN, "MSX Cartridge - Holy Quran", tag, owner, clock, "msx_cart_holy_quran", __FILE__) , msx_cart_interface(mconfig, *this) , m_decrypt(false) { for (int i = 0; i < 4; i++) { m_selected_bank[i] = 0; m_bank_base[i] = NULL; } /* protection uses a simple rotation on databus, some lines inverted: D0 D4 D4 D5 D1 ~ D3 D5 ~ D2 D2 ~ D6 D6 D7 D3 ~ D0 D7 D1 */ for (int i=0; i < 0x100; i++) { m_lookup_prot[i] = (((i << 4) & 0x50) | ((i >> 3) & 5) | ((i << 1) & 0xa0) | ((i << 2) & 8) | ((i >> 6) & 2)) ^ 0x4d; } } void msx_cart_holy_quran::device_start() { save_item(NAME(m_selected_bank)); save_item(NAME(m_decrypt)); machine().save().register_postload(save_prepost_delegate(FUNC(msx_cart_holy_quran::restore_banks), this)); } void msx_cart_holy_quran::restore_banks() { m_bank_base[0] = get_rom_base() + (m_selected_bank[0] & 0x7f) * 0x2000; m_bank_base[1] = get_rom_base() + (m_selected_bank[1] & 0x7f) * 0x2000; m_bank_base[2] = get_rom_base() + (m_selected_bank[2] & 0x7f) * 0x2000; m_bank_base[3] = get_rom_base() + (m_selected_bank[3] & 0x7f) * 0x2000; } void msx_cart_holy_quran::device_reset() { for (int i = 0; i < 4; i++) { m_selected_bank[i] = 0; } } void msx_cart_holy_quran::initialize_cartridge() { if (get_rom_size() != 0x100000) { fatalerror("holy_quran: Invalid ROM size\n"); } restore_banks(); } READ8_MEMBER(msx_cart_holy_quran::read_cart) { if (offset >= 0x4000 && offset < 0xc000) { UINT8 data = m_bank_base[(offset - 0x4000) >> 13][offset & 0x1fff]; if (m_decrypt) { return m_lookup_prot[data]; } // The decryption should actually start working after the first M1 cycle executing something // from the cartridge. if (offset == ((m_rom[3] << 8) | m_rom[2]) && !space.debugger_access()) { m_decrypt = true; } return data; } return 0xff; } WRITE8_MEMBER(msx_cart_holy_quran::write_cart) { switch (offset) { case 0x5000: m_selected_bank[0] = data; restore_banks(); break; case 0x5400: m_selected_bank[1] = data; restore_banks(); break; case 0x5800: m_selected_bank[2] = data; restore_banks(); break; case 0x5c00: m_selected_bank[3] = data; restore_banks(); break; default: logerror("msx_cart_holy_quran: unhandled write %02x to %04x\n", data, offset); break; } }