// 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 "machine/7200fifo.h"
const device_type FIFO7200 = &device_creator<fifo7200_device>;
//-------------------------------------------------
// fifo7200_device - constructor
//-------------------------------------------------
fifo7200_device::fifo7200_device(const machine_config &mconfig, std::string tag, device_t *owner, UINT32 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 data)
{
if (m_ff)
{
logerror("IDT7200 %s fifo_write overflow!\n", tag().c_str());
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 fifo7200_device::fifo_read()
{
if (m_ef)
{
logerror("IDT7200 %s fifo_read underflow!\n", tag().c_str());
return 0x1ff;
}
UINT16 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;
}