void i8251_device::device_reset()
{
LOG(("I8251: Reset\n"));
/* what is the default setup when the 8251 has been reset??? */
/* i8251 datasheet explains the state of tx pin at reset */
/* tx is set to 1 */
set_out_data_bit(1);
/* assumption, rts is set to 1 */
m_connection_state &= ~SERIAL_STATE_RTS;
serial_connection_out();
transmit_register_reset();
receive_register_reset();
/* expecting mode byte */
m_flags |= I8251_EXPECTING_MODE;
/* not expecting a sync byte */
m_flags &= ~I8251_EXPECTING_SYNC_BYTE;
/* no character to read by cpu */
/* transmitter is ready and is empty */
m_status = I8251_STATUS_TX_EMPTY | I8251_STATUS_TX_READY;
m_mode_byte = 0;
m_command = 0;
/* update tx empty pin output */
update_tx_empty();
/* update rx ready pin output */
update_rx_ready();
/* update tx ready pin output */
update_tx_ready();
}
void i8251_device::transmit_clock()
{
m_txc_count++;
if (m_txc_count != m_br_factor)
return;
m_txc_count = 0;
if (is_transmit_register_empty())
{
if ((m_status & I8251_STATUS_TX_READY) == 0 && (is_tx_enabled() || (m_flags & I8251_DELAYED_TX_EN) != 0))
start_tx();
else
m_status |= I8251_STATUS_TX_EMPTY;
update_tx_ready();
update_tx_empty();
}
/* if diserial has bits to send, make them so */
if (!is_transmit_register_empty())
{
uint8_t data = transmit_register_get_data_bit();
m_txd_handler(data);
}
#if 0
/* hunt mode? */
/* after each bit has been shifted in, it is compared against the current sync byte */
if (BIT(m_command, 7))
{
/* data matches sync byte? */
if (m_data == m_sync_bytes[m_sync_byte_offset])
{
/* sync byte matches */
/* update for next sync byte? */
m_sync_byte_offset++;
/* do all sync bytes match? */
if (m_sync_byte_offset == m_sync_byte_count)
{
/* ent hunt mode */
m_command &= ~(1<<7);
}
}
else
{
/* if there is no match, reset */
m_sync_byte_offset = 0;
}
}
#endif
}
void i8251_device::device_reset()
{
LOG("I8251: Reset\n");
/* what is the default setup when the 8251 has been reset??? */
/* i8251 datasheet explains the state of tx pin at reset */
/* tx is set to 1 */
m_txd_handler(1);
/* assumption */
m_rts_handler(1);
m_dtr_handler(1);
transmit_register_reset();
receive_register_reset();
m_flags = 0;
/* expecting mode byte */
m_flags |= I8251_EXPECTING_MODE;
/* not expecting a sync byte */
m_flags &= ~I8251_EXPECTING_SYNC_BYTE;
/* no character to read by cpu */
/* transmitter is ready and is empty */
m_status = I8251_STATUS_TX_EMPTY | I8251_STATUS_TX_READY;
m_mode_byte = 0;
m_command = 0;
m_rx_data = 0;
m_tx_data = 0;
m_rxc_count = m_txc_count = 0;
m_br_factor = 1;
/* update tx empty pin output */
update_tx_empty();
/* update rx ready pin output */
update_rx_ready();
/* update tx ready pin output */
update_tx_ready();
}
void i8251_device::transmit_clock()
{
/* transmit enable? */
if (m_command & (1<<0))
{
/* transmit register full? */
if ((m_status & I8251_STATUS_TX_READY)==0)
{
/* if transmit reg is empty */
if (is_transmit_register_empty())
{
/* set it up */
transmit_register_setup(m_data);
/* i8251 transmit reg now empty */
m_status |=I8251_STATUS_TX_EMPTY;
/* ready for next transmit */
m_status |=I8251_STATUS_TX_READY;
update_tx_empty();
update_tx_ready();
}
}
/* if transmit is not empty... transmit data */
if (!is_transmit_register_empty())
{
UINT8 data = transmit_register_get_data_bit();
// logerror("I8251\n");
//transmit_register_send_bit();
m_out_txd_func(data);
m_connection_state &=~SERIAL_STATE_TX_DATA;
m_connection_state|=(data<<5);
serial_connection_out();
}
}
#if 0
/* hunt mode? */
/* after each bit has been shifted in, it is compared against the current sync byte */
if (m_command & (1<<7))
{
/* data matches sync byte? */
if (m_data == m_sync_bytes[m_sync_byte_offset])
{
/* sync byte matches */
/* update for next sync byte? */
m_sync_byte_offset++;
/* do all sync bytes match? */
if (m_sync_byte_offset == m_sync_byte_count)
{
/* ent hunt mode */
m_command &=~(1<<7);
}
}
else
{
/* if there is no match, reset */
m_sync_byte_offset = 0;
}
}
#endif
}
void i8251_device::transmit_clock()
{
m_txc_count++;
if (m_txc_count == m_br_factor)
m_txc_count = 0;
else
return;
/* transmit enabled? */
if (m_command & (1<<0))
{
/* do we have a character to send? */
if ((m_status & I8251_STATUS_TX_READY)==0)
{
/* is diserial ready for it? */
if (is_transmit_register_empty())
{
/* set it up */
transmit_register_setup(m_data);
/* i8251 transmit reg now empty */
m_status |=I8251_STATUS_TX_EMPTY;
/* ready for next transmit */
m_status |=I8251_STATUS_TX_READY;
update_tx_empty();
update_tx_ready();
}
}
/* if diserial has bits to send, make them so */
if (!is_transmit_register_empty())
{
UINT8 data = transmit_register_get_data_bit();
m_tx_busy = true;
m_txd_handler(data);
}
// is transmitter totally done?
if ((m_status & I8251_STATUS_TX_READY) && is_transmit_register_empty())
{
m_tx_busy = false;
if (m_disable_tx_pending)
{
LOG(("Applying pending disable\n"));
m_disable_tx_pending = false;
m_command &= ~(1<<0);
m_txd_handler(1);
update_tx_ready();
}
}
}
#if 0
/* hunt mode? */
/* after each bit has been shifted in, it is compared against the current sync byte */
if (m_command & (1<<7))
{
/* data matches sync byte? */
if (m_data == m_sync_bytes[m_sync_byte_offset])
{
/* sync byte matches */
/* update for next sync byte? */
m_sync_byte_offset++;
/* do all sync bytes match? */
if (m_sync_byte_offset == m_sync_byte_count)
{
/* ent hunt mode */
m_command &=~(1<<7);
}
}
else
{
/* if there is no match, reset */
m_sync_byte_offset = 0;
}
}
#endif
}
