void *read_serial_packet(serial_source src, int *len)
/* Effects: Read the serial source src. If a packet is available, return it.
If in blocking mode and no packet is available, wait for one.
Returns: the packet read (in newly allocated memory), with *len is
set to the packet length, or NULL if no packet is yet available and
the serial source is in non-blocking mode
*/
{
read_and_process(src, TRUE);
for (;;)
{
struct packet_list *entry;
entry = pop_protocol_packet(src, P_PACKET_NO_ACK);
if (entry)
{
uint8_t *packet = entry->packet;
*len = entry->len;
free(entry);
return packet;
}
if (src->non_blocking && serial_source_empty(src))
return NULL;
source_wait(src, NULL);
read_and_process(src, src->non_blocking);
}
}
int write_serial_packet(serial_source src, const void *packet, int len)
/* Effects: writes len byte packet to serial source src
Returns: 0 if packet successfully written, 1 if successfully written
but not acknowledged, -1 otherwise
*/
{
struct timeval deadline;
src->send.seqno++;
if (write_framed_packet(src, P_PACKET_ACK, src->send.seqno, packet, len) < 0)
return -1;
gettimeofday(&deadline, NULL);
add_timeval(&deadline, ACK_TIMEOUT);
for (;;)
{
struct packet_list *entry;
read_and_process(src);
entry = pop_protocol_packet(src, P_ACK);
if (entry)
{
uint8_t acked = entry->packet[0];
free(entry->packet);
free(entry);
if (acked == src->send.seqno)
return 0;
}
else if (source_wait(src, &deadline) < 0)
return 1;
}
}