// license:BSD-3-Clause // copyright-holders:Curt Coder /********************************************************************** Intel 8155/8156 - 2048-Bit Static MOS RAM with I/O Ports and Timer emulation **********************************************************************/ /* TODO: - strobed mode */ #include "emu.h" #include "i8155.h" // device type definitions const device_type I8155 = &device_creator; const device_type I8156 = &device_creator; //************************************************************************** // MACROS / CONSTANTS //************************************************************************** #define LOG 0 enum { REGISTER_COMMAND = 0, REGISTER_STATUS = 0, REGISTER_PORT_A, REGISTER_PORT_B, REGISTER_PORT_C, REGISTER_TIMER_LOW, REGISTER_TIMER_HIGH }; enum { PORT_A = 0, PORT_B, PORT_C, PORT_COUNT }; enum { PORT_MODE_INPUT = 0, PORT_MODE_OUTPUT, PORT_MODE_STROBED_PORT_A, // not supported PORT_MODE_STROBED // not supported }; enum { MEMORY = 0, IO }; #define COMMAND_PA 0x01 #define COMMAND_PB 0x02 #define COMMAND_PC_MASK 0x0c #define COMMAND_PC_ALT_1 0x00 #define COMMAND_PC_ALT_2 0x0c #define COMMAND_PC_ALT_3 0x04 // not supported #define COMMAND_PC_ALT_4 0x08 // not supported #define COMMAND_IEA 0x10 // not supported #define COMMAND_IEB 0x20 // not supported #define COMMAND_TM_MASK 0xc0 #define COMMAND_TM_NOP 0x00 #define COMMAND_TM_STOP 0x40 #define COMMAND_TM_STOP_AFTER_TC 0x80 #define COMMAND_TM_START 0xc0 #define STATUS_INTR_A 0x01 // not supported #define STATUS_A_BF 0x02 // not supported #define STATUS_INTE_A 0x04 // not supported #define STATUS_INTR_B 0x08 // not supported #define STATUS_B_BF 0x10 // not supported #define STATUS_INTE_B 0x20 // not supported #define STATUS_TIMER 0x40 #define TIMER_MODE_MASK 0xc0 #define TIMER_MODE_LOW 0x00 #define TIMER_MODE_SQUARE_WAVE 0x40 #define TIMER_MODE_SINGLE_PULSE 0x80 #define TIMER_MODE_AUTOMATIC_RELOAD 0xc0 //************************************************************************** // GLOBAL VARIABLES //************************************************************************** // default address map static ADDRESS_MAP_START( i8155, AS_0, 8, i8155_device ) AM_RANGE(0x00, 0xff) AM_RAM ADDRESS_MAP_END //************************************************************************** // INLINE HELPERS //************************************************************************** inline uint8_t i8155_device::get_timer_mode() { return (m_count_length >> 8) & TIMER_MODE_MASK; } inline void i8155_device::timer_output() { m_out_to_cb(m_to); if (LOG) logerror("8155 Timer Output: %u\n", m_to); } inline void i8155_device::pulse_timer_output() { m_to = 0; timer_output(); m_to = 1; timer_output(); } inline int i8155_device::get_port_mode(int port) { int mode = -1; switch (port) { case PORT_A: mode = (m_command & COMMAND_PA) ? PORT_MODE_OUTPUT : PORT_MODE_INPUT; break; case PORT_B: mode = (m_command & COMMAND_PB) ? PORT_MODE_OUTPUT : PORT_MODE_INPUT; break; case PORT_C: switch (m_command & COMMAND_PC_MASK) { case COMMAND_PC_ALT_1: mode = PORT_MODE_INPUT; break; case COMMAND_PC_ALT_2: mode = PORT_MODE_OUTPUT; break; case COMMAND_PC_ALT_3: mode = PORT_MODE_STROBED_PORT_A; break; case COMMAND_PC_ALT_4: mode = PORT_MODE_STROBED; break; } break; } return mode; } inline uint8_t i8155_device::read_port(int port) { uint8_t data = 0; switch (get_port_mode(port)) { case PORT_MODE_INPUT: data = (port == PORT_A) ? m_in_pa_cb(0) : ((port == PORT_B) ? m_in_pb_cb(0) : m_in_pc_cb(0)); break; case PORT_MODE_OUTPUT: data = m_output[port]; break; default: // strobed mode not implemented yet logerror("8155 Unsupported Port C mode!\n"); break; } return data; } inline void i8155_device::write_port(int port, uint8_t data) { switch (get_port_mode(port)) { case PORT_MODE_OUTPUT: m_output[port] = data; if (port == PORT_A) m_out_pa_cb((offs_t)0, m_output[port]); else if (port == PORT_B) m_out_pb_cb((offs_t)0, m_output[port]); else m_out_pc_cb((offs_t)0, m_output[port]); break; } } //************************************************************************** // LIVE DEVICE //************************************************************************** //------------------------------------------------- // i8155_device - constructor //------------------------------------------------- i8155_device::i8155_device(const machine_config &mconfig, const char *tag, device_t *owner, uint32_t clock) : device_t(mconfig, I8155, "8155 RIOT", tag, owner, clock, "i8155", __FILE__), device_memory_interface(mconfig, *this), m_in_pa_cb(*this), m_in_pb_cb(*this), m_in_pc_cb(*this), m_out_pa_cb(*this), m_out_pb_cb(*this), m_out_pc_cb(*this), m_out_to_cb(*this), m_command(0), m_status(0), m_space_config("ram", ENDIANNESS_LITTLE, 8, 8, 0, nullptr, *ADDRESS_MAP_NAME(i8155)) { } //------------------------------------------------- // device_start - device-specific startup //------------------------------------------------- void i8155_device::device_start() { // resolve callbacks m_in_pa_cb.resolve_safe(0); m_in_pb_cb.resolve_safe(0); m_in_pc_cb.resolve_safe(0); m_out_pa_cb.resolve_safe(); m_out_pb_cb.resolve_safe(); m_out_pc_cb.resolve_safe(); m_out_to_cb.resolve_safe(); // allocate timers m_timer = timer_alloc(); // register for state saving save_item(NAME(m_io_m)); save_item(NAME(m_ad)); save_item(NAME(m_command)); save_item(NAME(m_status)); save_item(NAME(m_output)); save_item(NAME(m_count_length)); save_item(NAME(m_counter)); save_item(NAME(m_to)); } //------------------------------------------------- // device_reset - device-specific reset //------------------------------------------------- void i8155_device::device_reset() { // clear output registers m_output[PORT_A] = 0; m_output[PORT_B] = 0; m_output[PORT_C] = 0; // set ports to input mode register_w(REGISTER_COMMAND, m_command & ~(COMMAND_PA | COMMAND_PB | COMMAND_PC_MASK)); // clear timer flag m_status &= ~STATUS_TIMER; // stop counting m_timer->enable(0); // clear timer output m_to = 1; timer_output(); } //------------------------------------------------- // device_timer - handler timer events //------------------------------------------------- void i8155_device::device_timer(emu_timer &timer, device_timer_id id, int param, void *ptr) { // count down m_counter--; if (get_timer_mode() == TIMER_MODE_LOW) { // pulse on every count pulse_timer_output(); } if (m_counter == 0) { if (LOG) logerror("8155 Timer Count Reached\n"); switch (get_timer_mode()) { case TIMER_MODE_LOW: case TIMER_MODE_SQUARE_WAVE: // toggle timer output m_to = !m_to; timer_output(); break; case TIMER_MODE_SINGLE_PULSE: case TIMER_MODE_AUTOMATIC_RELOAD: // pulse upon TC being reached pulse_timer_output(); break; } // set timer flag m_status |= STATUS_TIMER; if ((m_command & COMMAND_TM_MASK) == COMMAND_TM_START) { // load new timer counter m_counter = m_count_length & 0x3fff; if (LOG) logerror("8155 Timer New Start\n"); } else if ((m_command & COMMAND_TM_MASK) == COMMAND_TM_STOP_AFTER_TC || get_timer_mode() == TIMER_MODE_SINGLE_PULSE) { // stop timer m_timer->enable(0); if (LOG) logerror("8155 Timer Stopped\n"); } else { // automatically reload the counter m_counter = m_count_length & 0x3fff; } // clear timer command m_command &= ~COMMAND_TM_MASK; } } //------------------------------------------------- // memory_space_config - return a description of // any address spaces owned by this device //------------------------------------------------- const address_space_config *i8155_device::memory_space_config(address_spacenum spacenum) const { return (spacenum == AS_0) ? &m_space_config : nullptr; } //------------------------------------------------- // io_r - register read //------------------------------------------------- READ8_MEMBER( i8155_device::io_r ) { uint8_t data = 0; switch (offset & 0x07) { case REGISTER_STATUS: data = m_status; // clear timer flag m_status &= ~STATUS_TIMER; break; case REGISTER_PORT_A: data = read_port(PORT_A); break; case REGISTER_PORT_B: data = read_port(PORT_B); break; case REGISTER_PORT_C: data = read_port(PORT_C) | 0xc0; break; case REGISTER_TIMER_LOW: data = m_counter & 0xff; break; case REGISTER_TIMER_HIGH: data = (m_counter >> 8 & 0x3f) | get_timer_mode(); break; } return data; } //------------------------------------------------- // register_w - register write //------------------------------------------------- void i8155_device::register_w(int offset, uint8_t data) { switch (offset & 0x07) { case REGISTER_COMMAND: m_command = data; if (LOG) logerror("8155 Port A Mode: %s\n", (data & COMMAND_PA) ? "output" : "input"); if (LOG) logerror("8155 Port B Mode: %s\n", (data & COMMAND_PB) ? "output" : "input"); if (LOG) logerror("8155 Port A Interrupt: %s\n", (data & COMMAND_IEA) ? "enabled" : "disabled"); if (LOG) logerror("8155 Port B Interrupt: %s\n", (data & COMMAND_IEB) ? "enabled" : "disabled"); switch (data & COMMAND_PC_MASK) { case COMMAND_PC_ALT_1: if (LOG) logerror("8155 Port C Mode: Alt 1\n"); break; case COMMAND_PC_ALT_2: if (LOG) logerror("8155 Port C Mode: Alt 2\n"); break; case COMMAND_PC_ALT_3: if (LOG) logerror("8155 Port C Mode: Alt 3\n"); break; case COMMAND_PC_ALT_4: if (LOG) logerror("8155 Port C Mode: Alt 4\n"); break; } switch (data & COMMAND_TM_MASK) { case COMMAND_TM_NOP: // do not affect counter operation break; case COMMAND_TM_STOP: // NOP if timer has not started, stop counting if the timer is running if (LOG) logerror("8155 Timer Command: Stop\n"); m_to = 1; timer_output(); m_timer->enable(0); break; case COMMAND_TM_STOP_AFTER_TC: // stop immediately after present TC is reached (NOP if timer has not started) if (LOG) logerror("8155 Timer Command: Stop after TC\n"); break; case COMMAND_TM_START: if (LOG) logerror("8155 Timer Command: Start\n"); if (m_timer->enabled()) { // if timer is running, start the new mode and CNT length immediately after present TC is reached } else { // load mode and CNT length and start immediately after loading (if timer is not running) m_counter = m_count_length & 0x3fff; m_timer->adjust(attotime::zero, 0, attotime::from_hz(clock())); // clear timer command so this won't execute twice m_command &= ~COMMAND_TM_MASK; } break; } break; case REGISTER_PORT_A: write_port(PORT_A, data); break; case REGISTER_PORT_B: write_port(PORT_B, data); break; case REGISTER_PORT_C: write_port(PORT_C, data & 0x3f); break; case REGISTER_TIMER_LOW: m_count_length = (m_count_length & 0xff00) | data; if (LOG) logerror("8155 Count Length Low: %04x\n", m_count_length); break; case REGISTER_TIMER_HIGH: m_count_length = (data << 8) | (m_count_length & 0xff); if (LOG) logerror("8155 Count Length High: %04x\n", m_count_length); switch (data & TIMER_MODE_MASK) { case TIMER_MODE_LOW: // puts out LOW during second half of count if (LOG) logerror("8155 Timer Mode: LOW\n"); break; case TIMER_MODE_SQUARE_WAVE: // square wave, i.e. the period of the square wave equals the count length programmed with automatic reload at terminal count if (LOG) logerror("8155 Timer Mode: Square wave\n"); break; case TIMER_MODE_SINGLE_PULSE: // single pulse upon TC being reached if (LOG) logerror("8155 Timer Mode: Single pulse\n"); break; case TIMER_MODE_AUTOMATIC_RELOAD: // automatic reload, i.e. single pulse every time TC is reached if (LOG) logerror("8155 Timer Mode: Automatic reload\n"); break; } break; } } //------------------------------------------------- // io_w - register write //------------------------------------------------- WRITE8_MEMBER( i8155_device::io_w ) { register_w(offset, data); } //------------------------------------------------- // memory_r - internal RAM read //------------------------------------------------- READ8_MEMBER( i8155_device::memory_r ) { return this->space().read_byte(offset); } //------------------------------------------------- // memory_w - internal RAM write //------------------------------------------------- WRITE8_MEMBER( i8155_device::memory_w ) { this->space().write_byte(offset, data); } //------------------------------------------------- // ale_w - address latch write //------------------------------------------------- WRITE8_MEMBER( i8155_device::ale_w ) { // I/O / memory select m_io_m = BIT(offset, 0); // address m_ad = data; } //------------------------------------------------- // read - memory or I/O read //------------------------------------------------- READ8_MEMBER( i8155_device::read ) { uint8_t data = 0; switch (m_io_m) { case MEMORY: data = memory_r(space, m_ad); break; case IO: data = io_r(space, m_ad); break; } return data; } //------------------------------------------------- // write - memory or I/O write //------------------------------------------------- WRITE8_MEMBER( i8155_device::write ) { switch (m_io_m) { case MEMORY: memory_w(space, m_ad, data); break; case IO: io_w(space, m_ad, data); break; } }