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n68681: make loopback operate at the current baud rate instead of instantaneously. Fixes dectalk DUART self-test. [R. Belmont]

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R. Belmont 2014-01-24 03:03:46 +00:00
parent 97fa5db119
commit e34abeff81
1 changed files with 62 additions and 60 deletions
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122
src/emu/machine/n68681.c
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@ -671,20 +671,47 @@ void duart68681_channel::tra_complete()
else
m_uart->clear_ISR_bits(INT_TXRDYB);
// if local loopback is on, write the transmitted data as if a byte had been received
if ((MR2 & 0xC0) == 0x80)
{
if (rx_fifo_num >= MC68681_RX_FIFO_SIZE)
{
LOG(( "68681: FIFO overflow\n" ));
SR |= STATUS_OVERRUN_ERROR;
}
else
{
rx_fifo[rx_fifo_write_ptr++]= tx_data;
if (rx_fifo_write_ptr == MC68681_RX_FIFO_SIZE)
{
rx_fifo_write_ptr = 0;
}
rx_fifo_num++;
}
}
update_interrupts();
}
void duart68681_channel::tra_callback()
{
int bit = transmit_register_get_data_bit();
// printf("ch %d transmit %d\n", m_ch, bit);
if (m_ch == 0)
// don't actually send in loopback mode
if ((MR2&0xC0) != 0x80)
{
m_uart->write_a_tx(bit);
int bit = transmit_register_get_data_bit();
// printf("ch %d transmit %d\n", m_ch, bit);
if (m_ch == 0)
{
m_uart->write_a_tx(bit);
}
else
{
m_uart->write_b_tx(bit);
}
}
else
else // must call this to advance the transmitter
{
m_uart->write_b_tx(bit);
transmit_register_get_data_bit();
}
}
@ -694,21 +721,24 @@ void duart68681_channel::input_callback(UINT8 state)
void duart68681_channel::update_interrupts()
{
if ( rx_fifo_num > 0 )
if (rx_enabled)
{
SR |= STATUS_RECEIVER_READY;
}
else
{
SR &= ~STATUS_RECEIVER_READY;
}
if ( rx_fifo_num == MC68681_RX_FIFO_SIZE )
{
SR |= STATUS_FIFO_FULL;
}
else
{
SR &= ~STATUS_FIFO_FULL;
if (rx_fifo_num > 0)
{
SR |= STATUS_RECEIVER_READY;
}
else
{
SR &= ~STATUS_RECEIVER_READY;
}
if ( rx_fifo_num == MC68681_RX_FIFO_SIZE )
{
SR |= STATUS_FIFO_FULL;
}
else
{
SR &= ~STATUS_FIFO_FULL;
}
}
// Handle the TxEMT and TxRDY bits based on mode
@ -809,6 +839,8 @@ UINT8 duart68681_channel::read_rx_fifo()
rx_fifo_num--;
update_interrupts();
// printf("Rx read %02x\n", rv);
return rv;
};
@ -857,7 +889,7 @@ void duart68681_channel::write_chan_reg(int reg, UINT8 data)
CSR = data;
tx_baud_rate = m_uart->calc_baud(m_ch, data & 0xf);
rx_baud_rate = m_uart->calc_baud(m_ch, (data>>4) & 0xf);
//printf("ch %d CSR %02x Tx baud %d Rx baud %d\n", m_ch, data, tx_baud_rate, rx_baud_rate);
// printf("ch %d CSR %02x Tx baud %d Rx baud %d\n", m_ch, data, tx_baud_rate, rx_baud_rate);
set_rcv_rate(rx_baud_rate);
set_tra_rate(tx_baud_rate);
break;
@ -1032,48 +1064,18 @@ void duart68681_channel::write_TX(UINT8 data)
printf("Write %02x to TX when TX not ready!\n", data);
}*/
// printf("ch %d Tx %02x\n", m_ch, data);
// printf("ch %d Tx %02x\n", m_ch, data);
// send the byte unless we're in loopback mode;
// in loopback mode do NOT 'actually' send the byte: the TXn pin is held high when loopback mode is on.
if ((MR2&0xC0) != 0x80)
{
tx_ready = 0;
SR &= ~STATUS_TRANSMITTER_READY;
tx_ready = 0;
SR &= ~STATUS_TRANSMITTER_READY;
if (m_ch == 0)
m_uart->clear_ISR_bits(INT_TXRDYA);
else
m_uart->clear_ISR_bits(INT_TXRDYB);
if (m_ch == 0)
m_uart->clear_ISR_bits(INT_TXRDYA);
else
m_uart->clear_ISR_bits(INT_TXRDYB);
// send tx_data
transmit_register_setup(tx_data);
}
// if local loopback is on, write the transmitted data as if a byte had been received
else if ((MR2 & 0xC0) == 0x80)
{
if (rx_fifo_num >= MC68681_RX_FIFO_SIZE)
{
LOG(( "68681: FIFO overflow\n" ));
SR |= STATUS_OVERRUN_ERROR;
}
else
{
rx_fifo[rx_fifo_write_ptr++]= tx_data;
if (rx_fifo_write_ptr == MC68681_RX_FIFO_SIZE)
{
rx_fifo_write_ptr = 0;
}
rx_fifo_num++;
}
tx_ready = 1;
SR |= STATUS_TRANSMITTER_READY;
if (m_ch == 0)
m_uart->set_ISR_bits(INT_TXRDYA);
else
m_uart->set_ISR_bits(INT_TXRDYB);
}
// send tx_data
transmit_register_setup(tx_data);
update_interrupts();
};