// 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 "7200fifo.h" DEFINE_DEVICE_TYPE(IDT7200, idt7200_device, "idt7200", "IDT7200 FIFO (256x9)") DEFINE_DEVICE_TYPE(IDT7201, idt7201_device, "idt7201", "IDT7201 FIFO (512x9)") DEFINE_DEVICE_TYPE(IDT7202, idt7202_device, "idt7202", "IDT7202 FIFO (1024x9)") //------------------------------------------------- // fifo7200_device - constructor //------------------------------------------------- fifo7200_device::fifo7200_device(const machine_config &mconfig, device_type type, const char *tag, device_t *owner, int size) : device_t(mconfig, type, tag, owner, (uint32_t)0), m_ram_size(size), 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) { } //------------------------------------------------- // idt7200_device - constructor //------------------------------------------------- idt7200_device::idt7200_device(const machine_config &mconfig, const char *tag, device_t *owner, uint32_t clock) : fifo7200_device(mconfig, IDT7200, tag, owner, 0x100) { } //------------------------------------------------- // idt7201_device - constructor //------------------------------------------------- idt7201_device::idt7201_device(const machine_config &mconfig, const char *tag, device_t *owner, uint32_t clock) : fifo7200_device(mconfig, IDT7201, tag, owner, 0x200) { } //------------------------------------------------- // idt7202_device - constructor //------------------------------------------------- idt7202_device::idt7202_device(const machine_config &mconfig, const char *tag, device_t *owner, uint32_t clock) : fifo7200_device(mconfig, IDT7202, tag, owner, 0x400) { } //------------------------------------------------- // 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); // 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 std::fill(m_buffer.begin(), m_buffer.end(), 0); 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_hf && (fifo_used() >= m_ram_size / 2)) { m_hf = 1; m_hf_handler(!m_hf); } } uint16_t fifo7200_device::fifo_read() { if (m_ef) { if (!machine().side_effects_disabled()) logerror("IDT7200 %s fifo_read underflow!\n", tag()); return 0x1ff; } uint16_t ret = m_buffer[m_read_ptr]; if (!machine().side_effects_disabled()) { 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_hf && (fifo_used() < m_ram_size / 2)) { m_hf = 0; m_hf_handler(!m_hf); } } return ret; } int fifo7200_device::fifo_used() { int ret = m_ram_size; if (!m_ff) { if (m_write_ptr >= m_read_ptr) { ret = m_write_ptr - m_read_ptr; } else { ret = m_ram_size + m_write_ptr - m_read_ptr; } } return ret; }