// license:BSD-3-Clause // copyright-holders:R. Belmont, Mark Garlanger /********************************************************************** National Semiconductor MM5740 Keyboard Encoder emulation (Code originally based on kb3600.cpp) *********************************************************************/ #include "emu.h" #include "mm5740.h" #include //************************************************************************** // GLOBAL VARIABLES //************************************************************************** // devices DEFINE_DEVICE_TYPE(MM5740, mm5740_device, "mm5740", "MM5740 Keyboard Encoder") //************************************************************************** // DEVICE DEFINITIONS //************************************************************************** ROM_START( mm5740 ) ROM_REGION(0x1c2, "internal", 0) ROM_LOAD("mm5740aac.ic1", 0x000, 0x1c2, CRC(aed404d3) SHA1(e7b9feba5f789f388d27820b5f3fa591d41b4ab1)) ROM_END //------------------------------------------------- // rom_region - device-specific ROM region //------------------------------------------------- const tiny_rom_entry *mm5740_device::device_rom_region() const { return ROM_NAME( mm5740 ); } //------------------------------------------------- // mm5740_device - constructor //------------------------------------------------- mm5740_device::mm5740_device(const machine_config &mconfig, const char *tag, device_t *owner, uint32_t clock) : device_t(mconfig, MM5740, tag, owner, clock), m_read_x{{*this}, {*this}, {*this}, {*this}, {*this}, {*this}, {*this}, {*this}, {*this}}, m_read_shift(*this), m_read_control(*this), m_write_data_ready(*this), m_rom(*this, "internal") { std::fill_n(m_x_mask, 9, 0); } uint32_t mm5740_device::calc_effective_clock_key_debounce(uint32_t capacitance) { // calculate key debounce based on capacitance in pF uint32_t key_debounce_msec = capacitance / 125; if (key_debounce_msec == 0) { key_debounce_msec = 1; } return 1000 / key_debounce_msec; } //------------------------------------------------- // device_start - device-specific startup //------------------------------------------------- void mm5740_device::device_start() { // resolve callbacks for(int i = 0; i < 9; i++) { m_read_x[i].resolve_safe(0x3ff); } m_read_shift.resolve_safe(0); m_read_control.resolve_safe(0); m_write_data_ready.resolve_safe(); // allocate timers m_scan_timer = timer_alloc(); m_scan_timer->adjust(attotime::from_hz(clock()), 0, attotime::from_hz(clock())); // state saving save_item(NAME(m_b)); save_item(NAME(m_x_mask)); } //------------------------------------------------- // device_start - device-specific reset //------------------------------------------------- void mm5740_device::device_reset() { } //------------------------------------------------- // device_timer - handler timer events //------------------------------------------------- void mm5740_device::device_timer(emu_timer &timer, device_timer_id id, int param, void *ptr) { int ako = 0; for (int x = 0; x < 9; x++) { uint16_t data = m_read_x[x]() ^ 0x3ff; if ((data ^ m_x_mask[x]) == 0) { // bail early if nothing has changed. continue; } for (int y = 0; y < 10; y++) { if (BIT(data, y)) { uint8_t *rom = m_rom->base(); uint16_t offset = x*10 + y; // Common portion uint16_t common = (uint16_t) rom[offset]; offset += (((m_read_shift() ? 1: 0) + (m_read_control() ? 2: 0)) + 1) * 90; // Unique portion based on shift/ctrl keys. uint8_t uniq = rom[offset]; uint16_t b = (((common & 0x10) << 4) | ((uniq & 0x0f) << 4) | (common & 0x0f)) ^ 0x1ff; ako = 1; if (!BIT(m_x_mask[x], y)) { m_x_mask[x] |= (1 << y); if (m_b != b) { m_b = b; m_write_data_ready(ASSERT_LINE); return; } } } else // key released, unmark it from the "down" info { m_x_mask[x] &= ~(1 << y); } } } if (!ako) { m_write_data_ready(CLEAR_LINE); m_b = -1; } } //------------------------------------------------- // b_r - //------------------------------------------------- uint16_t mm5740_device::b_r() { m_write_data_ready(CLEAR_LINE); return m_b; }