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Automatically re-transmit corrupt data packets

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Originally packets are only retried when a valid NAK packet with the
busy error code is received. The retrying is now enabled for other types
of errors also, such as data packets with checksum errors.
This commit is contained in:
Jef Driesen 2017-06-13 16:31:16 +02:00
parent 37392a03f2
commit 31c68ba338
1 changed files with 73 additions and 51 deletions
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124
src/divesystem_idive.c
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@ -291,72 +291,94 @@ divesystem_idive_receive (divesystem_idive_device_t *device, unsigned char answe
static dc_status_t
divesystem_idive_transfer (divesystem_idive_device_t *device, const unsigned char command[], unsigned int csize, unsigned char answer[], unsigned int asize)
divesystem_idive_packet (divesystem_idive_device_t *device, const unsigned char command[], unsigned int csize, unsigned char answer[], unsigned int asize, unsigned int *errorcode)
{
dc_status_t rc = DC_STATUS_SUCCESS;
dc_status_t status = DC_STATUS_SUCCESS;
dc_device_t *abstract = (dc_device_t *) device;
unsigned char packet[MAXPACKET] = {0};
unsigned int length = 0;
unsigned int nretries = 0;
unsigned int length = sizeof(packet);
unsigned int errcode = 0;
while (1) {
// Send the command.
rc = divesystem_idive_send (device, command, csize);
if (rc != DC_STATUS_SUCCESS)
return rc;
// Send the command.
status = divesystem_idive_send (device, command, csize);
if (status != DC_STATUS_SUCCESS) {
goto error;
}
// Receive the answer.
length = sizeof(packet);
rc = divesystem_idive_receive (device, packet, &length);
if (rc != DC_STATUS_SUCCESS)
return rc;
// Receive the answer.
status = divesystem_idive_receive (device, packet, &length);
if (status != DC_STATUS_SUCCESS) {
goto error;
}
// Verify the command byte.
if (packet[0] != command[0]) {
ERROR (abstract->context, "Unexpected packet header.");
return DC_STATUS_PROTOCOL;
}
// Verify the command byte.
if (packet[0] != command[0]) {
ERROR (abstract->context, "Unexpected packet header.");
status = DC_STATUS_PROTOCOL;
goto error;
}
// Check the ACK byte.
if (packet[length - 1] == ACK)
break;
// Verify the NAK byte.
if (packet[length - 1] != NAK) {
ERROR (abstract->context, "Unexpected ACK/NAK byte.");
return DC_STATUS_PROTOCOL;
}
// Verify the length of the packet.
if (length != 3) {
ERROR (abstract->context, "Unexpected packet length.");
return DC_STATUS_PROTOCOL;
}
// Verify the error code.
unsigned int errcode = packet[1];
if (errcode != BUSY) {
ERROR (abstract->context, "Received NAK packet with error code %02x.", errcode);
return DC_STATUS_PROTOCOL;
}
// Abort if the maximum number of retries is reached.
if (nretries++ >= MAXRETRIES)
return DC_STATUS_PROTOCOL;
// Delay the next attempt.
dc_serial_sleep(device->port, 100);
// Verify the ACK/NAK byte.
unsigned int type = packet[length - 1];
if (type != ACK && type != NAK) {
ERROR (abstract->context, "Unexpected ACK/NAK byte.");
status = DC_STATUS_PROTOCOL;
goto error;
}
// Verify the length of the packet.
if (asize != length - 2) {
unsigned int expected = (type == ACK ? asize : 1) + 2;
if (length != expected) {
ERROR (abstract->context, "Unexpected packet length.");
return DC_STATUS_PROTOCOL;
status = DC_STATUS_PROTOCOL;
goto error;
}
// Get the error code from a NAK packet.
if (type == NAK) {
errcode = packet[1];
ERROR (abstract->context, "Received NAK packet with error code %02x.", errcode);
status = DC_STATUS_PROTOCOL;
goto error;
}
memcpy(answer, packet + 1, length - 2);
return DC_STATUS_SUCCESS;
error:
if (errorcode) {
*errorcode = errcode;
}
return status;
}
static dc_status_t
divesystem_idive_transfer (divesystem_idive_device_t *device, const unsigned char command[], unsigned int csize, unsigned char answer[], unsigned int asize)
{
dc_status_t status = DC_STATUS_SUCCESS;
unsigned int errcode = 0;
unsigned int nretries = 0;
while ((status = divesystem_idive_packet (device, command, csize, answer, asize, &errcode)) != DC_STATUS_SUCCESS) {
// Automatically discard a corrupted packet,
// and request a new one.
if (status != DC_STATUS_PROTOCOL && status != DC_STATUS_TIMEOUT)
break;
// Abort if the device reports a fatal error.
if (errcode && errcode != BUSY)
break;
// Abort if the maximum number of retries is reached.
if (nretries++ >= MAXRETRIES)
break;
// Delay the next attempt.
dc_serial_sleep (device->port, 100);
}
return status;
}
static dc_status_t