// license:BSD-3-Clause // copyright-holders:hap /********************************************************************** IDT7200 series 9-bit Asynchronous FIFO Emulation TODO: - retransmit (RT pin) - cascaded width expansion mode (when needed) **********************************************************************/ #include "emu.h" #include "machine/7200fifo.h" const device_type FIFO7200 = &device_creator; //------------------------------------------------- // fifo7200_device - constructor //------------------------------------------------- fifo7200_device::fifo7200_device(const machine_config &mconfig, const char *tag, device_t *owner, uint32_t clock) : device_t(mconfig, FIFO7200, "IDT7200 FIFO", tag, owner, clock, "fifo7200", __FILE__), m_ram_size(0), m_read_ptr(0), m_write_ptr(0), m_ef(0), m_ff(0), m_hf(0), m_ef_handler(*this), m_ff_handler(*this), m_hf_handler(*this) { } //------------------------------------------------- // device_start - device-specific startup //------------------------------------------------- void fifo7200_device::device_start() { assert(m_ram_size > 1 && ~m_ram_size & 1); m_buffer.resize(m_ram_size); // resolve callbacks m_ef_handler.resolve_safe(); m_ff_handler.resolve_safe(); m_hf_handler.resolve_safe(); // state save save_item(NAME(m_buffer)); save_item(NAME(m_read_ptr)); save_item(NAME(m_write_ptr)); save_item(NAME(m_ef)); save_item(NAME(m_ff)); save_item(NAME(m_hf)); } //------------------------------------------------- // device_reset - device-specific reset //------------------------------------------------- void fifo7200_device::device_reset() { // master reset m_buffer.clear(); m_read_ptr = 0; m_write_ptr = 0; m_ef = 1; m_ff = 0; m_hf = 0; m_ef_handler(!m_ef); m_ff_handler(!m_ff); m_hf_handler(!m_hf); } void fifo7200_device::fifo_write(uint16_t data) { if (m_ff) { logerror("IDT7200 %s fifo_write overflow!\n", tag()); return; } m_buffer[m_write_ptr] = data & 0x1ff; m_write_ptr = (m_write_ptr + 1) % m_ram_size; // update flags if (m_ef) { m_ef = 0; m_ef_handler(!m_ef); } else if (m_read_ptr == m_write_ptr) { m_ff = 1; m_ff_handler(!m_ff); } else if (((m_read_ptr + 1 + m_ram_size / 2) % m_ram_size) == m_write_ptr) { m_hf = 1; m_hf_handler(!m_hf); } } uint16_t fifo7200_device::fifo_read() { if (m_ef) { logerror("IDT7200 %s fifo_read underflow!\n", tag()); return 0x1ff; } uint16_t ret = m_buffer[m_read_ptr]; m_read_ptr = (m_read_ptr + 1) % m_ram_size; // update flags if (m_ff) { m_ff = 0; m_ff_handler(!m_ff); } else if (m_read_ptr == m_write_ptr) { m_ef = 1; m_ef_handler(!m_ef); } else if (((m_read_ptr + m_ram_size / 2) % m_ram_size) == m_write_ptr) { m_hf = 0; m_hf_handler(!m_hf); } return ret; }