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mc68681: Detect framing and parity errors, storing flags with FIFO characters

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mc68901: Detect framing and parity errors and signal Rx error interrupt if enabled
This commit is contained in:
AJR 2018-12-28 14:58:14 -05:00
parent f1f0591f43
commit 82a8efd61f
3 changed files with 61 additions and 51 deletions
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93
src/devices/machine/mc68681.cpp
View File

@ -48,6 +48,8 @@
#include "emu.h"
#include "mc68681.h"
#include <algorithm>
//#define VERBOSE 1
//#define LOG_OUTPUT_FUNC printf
#include "logmacro.h"
@ -87,6 +89,7 @@ static const int baud_rate_ACR_1_X_1[] = { 50, 110, 134, 200, 3600, 14400, 28800
#define STATUS_RECEIVER_READY 0x01
#define MODE_RX_INT_SELECT_BIT 0x40
#define MODE_BLOCK_ERROR 0x20
#define CHANA_TAG "cha"
#define CHANB_TAG "chb"
@ -1062,6 +1065,7 @@ duart_channel::duart_channel(const machine_config &mconfig, const char *tag, dev
, rx_fifo_num(0)
, tx_enabled(0)
{
std::fill_n(&rx_fifo[0], MC68681_RX_FIFO_SIZE, 0);
}
void duart_channel::device_start()
@ -1109,22 +1113,40 @@ void duart_channel::rcv_complete()
if (rx_enabled)
{
if (rx_fifo_num >= MC68681_RX_FIFO_SIZE)
{
logerror("68681: FIFO overflow\n");
SR |= STATUS_OVERRUN_ERROR;
return;
}
rx_fifo[rx_fifo_write_ptr++] = get_received_char();
if ( rx_fifo_write_ptr == MC68681_RX_FIFO_SIZE )
{
rx_fifo_write_ptr = 0;
}
rx_fifo_num++;
update_interrupts();
uint8_t errors = 0;
if (is_receive_framing_error())
errors |= STATUS_FRAMING_ERROR;
if (is_receive_parity_error())
errors |= STATUS_PARITY_ERROR;
rx_fifo_push(get_received_char(), errors);
}
}
void duart_channel::rx_fifo_push(uint8_t data, uint8_t errors)
{
if (rx_fifo_num >= MC68681_RX_FIFO_SIZE)
{
logerror("68681: FIFO overflow\n");
SR |= STATUS_OVERRUN_ERROR;
return;
}
rx_fifo[rx_fifo_write_ptr++] = data | (errors << 8);
if (rx_fifo_write_ptr == MC68681_RX_FIFO_SIZE)
rx_fifo_write_ptr = 0;
if (rx_fifo_num++ == 0)
{
SR |= STATUS_RECEIVER_READY;
if (!(MR1 & MODE_BLOCK_ERROR))
SR &= ~(STATUS_RECEIVED_BREAK | STATUS_FRAMING_ERROR | STATUS_PARITY_ERROR);
SR |= errors;
}
if (rx_fifo_num == MC68681_RX_FIFO_SIZE)
SR |= STATUS_FIFO_FULL;
update_interrupts();
}
void duart_channel::tra_complete()
{
//printf("%s ch %d Tx complete\n", tag(), m_ch);
@ -1138,22 +1160,7 @@ void duart_channel::tra_complete()
// 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++;
}
}
rx_fifo_push(tx_data, 0);
update_interrupts();
}
@ -1190,26 +1197,6 @@ void duart_channel::tra_callback()
void duart_channel::update_interrupts()
{
if (rx_enabled)
{
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
switch (MR2 & 0xc0) // what mode are we in?
{
@ -1298,6 +1285,13 @@ uint8_t duart_channel::read_rx_fifo()
}
rx_fifo_num--;
SR &= ~STATUS_FIFO_FULL;
if (!(MR1 & MODE_BLOCK_ERROR))
SR &= ~(STATUS_RECEIVED_BREAK | STATUS_FRAMING_ERROR | STATUS_PARITY_ERROR);
if (rx_fifo_num == 0)
SR &= ~STATUS_RECEIVER_READY;
else
SR |= rx_fifo[rx_fifo_read_ptr] >> 8;
update_interrupts();
//printf("Rx read %02x\n", rv);
@ -1446,6 +1440,7 @@ void duart_channel::write_CR(uint8_t data)
case 2: /* Reset channel receiver (disable receiver and flush fifo) */
rx_enabled = 0;
SR &= ~STATUS_RECEIVER_READY;
SR &= ~(STATUS_RECEIVED_BREAK | STATUS_FRAMING_ERROR | STATUS_PARITY_ERROR);
SR &= ~STATUS_OVERRUN_ERROR; // is this correct?
rx_fifo_read_ptr = 0;
rx_fifo_write_ptr = 0;

3
src/devices/machine/mc68681.h
View File

@ -57,6 +57,7 @@ public:
void write_chan_reg(int reg, uint8_t data);
void update_interrupts();
void rx_fifo_push(uint8_t data, uint8_t errors);
uint8_t read_rx_fifo();
void baud_updated();
@ -83,7 +84,7 @@ private:
/* Receiver */
uint8_t rx_enabled;
uint8_t rx_fifo[MC68681_RX_FIFO_SIZE];
uint16_t rx_fifo[MC68681_RX_FIFO_SIZE];
int rx_fifo_read_ptr;
int rx_fifo_write_ptr;
int rx_fifo_num;

16
src/devices/machine/mc68901.cpp
View File

@ -530,8 +530,22 @@ void mc68901_device::rcv_complete()
m_receive_buffer = get_received_char();
m_rsr |= RSR_BUFFER_FULL;
LOG("Received Character: %02x\n", m_receive_buffer);
if (is_receive_framing_error())
m_rsr |= RSR_FRAME_ERROR;
else
m_rsr &= ~RSR_FRAME_ERROR;
if (is_receive_parity_error())
m_rsr |= RSR_PARITY_ERROR;
else
m_rsr &= ~RSR_PARITY_ERROR;
if ((m_rsr & (RSR_FRAME_ERROR | RSR_PARITY_ERROR)) && (m_ier & IR_RCV_ERROR))
rx_error();
else
rx_buffer_full();
}
rx_buffer_full();
}