int read_packet(int id)
{
int ret = read_header(id);
/*
* Since we are reading with no timeout,
* a positive value indicates that the header is complete.
*/
if(ret > 0)
{
ret = read_value(id);
/*
* Since we are reading with no timeout,
* a non-negative value indicates that the value is complete.
*/
if(ret >= 0)
{
ret = adapter_process_packet(id, serials[id].data);
serials[id].bread = 0;
}
}
return ret;
}
/*
* \brief This function tries to read 'size' bytes of data.
*
* It blocks until 'size' bytes of data have been read or after 1s has elapsed.
* It should only be used in the initialization stages, i.e. before the mainloop.
*
* \param id the instance id
* \param pdata the pointer where to store the data
* \param size the number of bytes to retrieve
*
* \return the number of bytes actually read
*/
int serial_recv(int id, void* pdata, unsigned int size)
{
int bread = 0;
int res;
fd_set readfds;
struct timeval timeout = {.tv_sec = 1, .tv_usec = 0};
while(bread != size)
{
FD_ZERO(&readfds);
FD_SET(serials[id].fd, &readfds);
int status = select(serials[id].fd+1, &readfds, NULL, NULL, &timeout);
if(status > 0)
{
if(FD_ISSET(serials[id].fd, &readfds))
{
res = read(serials[id].fd, pdata, size-bread);
if(res > 0)
{
bread += res;
}
}
}
else if(status == EINTR)
{
continue;
}
else
{
break;
}
}
return bread;
}
/*
* \brief This function closes a serial port.
*
* \param id the instance id
*
* \return 0
*/
int serial_close(int id)
{
if(serials[id].fd >= 0)
{
usleep(10000);//sleep 10ms to leave enough time for the last packet to be sent
close(serials[id].fd);
serials[id].fd = -1;
}
return 0;
}
/*
* \brief the serial callback for serial ports that are added as event sources.
*
* \param id the instance id
*
* \return 0 in case of a success, -1 in case of an error
*/
static int serial_callback(int id)
{
int nread;
int ret = 0;
unsigned char* base = (unsigned char*)&serials[id].packet;
if(serials[id].bread < HEADER_SIZE)
{
/*
* read the first two bytes first so as to retrieve the data length
*/
nread = read(serials[id].fd, base+serials[id].bread, HEADER_SIZE-serials[id].bread);
if(nread >= 0)
{
serials[id].bread += nread;
}
else
{
fprintf(stderr, "%s:%d read: %m", __FILE__, __LINE__);
ret = -1;
}
}
else
{
/*
* read the data
*/
nread = read(serials[id].fd, base+serials[id].bread, serials[id].packet.header.length-(serials[id].bread-HEADER_SIZE));
if(nread >= 0)
{
serials[id].bread += nread;
if(serials[id].packet.header.length + HEADER_SIZE == serials[id].bread)
{
ret = adapter_process_packet(id, &serials[id].packet);
serials[id].bread = 0;
}
}
else
{
fprintf(stderr, "%s:%d read: %m", __FILE__, __LINE__);
ret = -1;
}
}
return ret;
}
