/** Method to update the readbuf of the serial communication,
* as well as the connection itself.
* @param connection
* the serial struct
* @note
* the packets will be read in the following format:
* data\n
* however, the \n will be cut off
*/
static void _serial_update(serial_t *connection) {
int numAvailable;
int totalBytes;
/* dynamically reconnect the device */
if (access(connection->port, F_OK) == -1) {
if (connection->connected) {
connection->connected = 0;
connection->fd = -1;
}
} else {
if (!connection->connected) {
if ((connection->fd = open(connection->port, O_RDWR | O_NOCTTY | O_NDELAY)) != -1) {
if (_serial_setattr(connection) == 0) {
connection->connected = 1;
} else {
close(connection->fd);
connection->fd = -1;
}
}
}
}
if (!connection->connected)
return;
/* update buffer */
if ((numAvailable = read(connection->fd, tempbuf, SWREADMAX)) > 0) {
char *start_index, *end_index;
tempbuf[numAvailable] = '\0';
if ((totalBytes = strlen(connection->buffer) + numAvailable) >= SWBUFMAX) {
totalBytes -= SWREADMAX;
memmove(connection->buffer, &connection->buffer[totalBytes],
(SWBUFMAX - totalBytes) * sizeof(char));
connection->buffer[SWBUFMAX - totalBytes] = '\0';
}
strcat(connection->buffer, tempbuf);
if ((end_index = strrchr(connection->buffer, '\n'))) {
end_index[0] = '\0';
end_index = &end_index[1];
start_index = strrchr(connection->buffer, '\n');
start_index = start_index ? &start_index[1] : connection->buffer;
memcpy(connection->readbuf, start_index,
(strlen(start_index) + 1) * sizeof(char));
memmove(connection->buffer, end_index,
(strlen(end_index) + 1) * sizeof(char));
connection->readAvailable = 1;
}
}
}
/** Connect to a serial device.
* @param connection
* a pointer to the serial struct
* @param port
* a portname; if NULL, will open a random port
* @param baudrate
* the bits per second of information to transmit/receive
* @return 0 on success, -1 on failure
*/
int serial_connect(serial_t *connection, char *port, int baudrate)
{
connection->connected = 0;
if (port)
{
connection->port = (char *)malloc((strlen(port) + 1) * sizeof(char));
strcpy(connection->port, port);
if ((connection->fd = open(connection->port, O_RDWR)) == -1)
{
goto error;
}
}
else
{
DIR *dp;
struct dirent *ent;
char hasPossibleSerial;
if (!(dp = opendir(INPUT_DIR)))
{
fprintf(stderr, "Cannot find directory %s to open serial connection\n", INPUT_DIR);
return -1;
}
while ((ent = readdir(dp)))
{
const char *prefix;
int i;
hasPossibleSerial = 0;
for (prefix = PREFIXES[(i = 0)]; prefix != NULL; prefix = PREFIXES[++i])
{
if (strstr(ent->d_name, prefix))
{
connection->port = (char *)malloc((strlen(INPUT_DIR) + strlen(ent->d_name) + 1) * sizeof(char));
sprintf(connection->port, "%s%s", INPUT_DIR, ent->d_name);
if ((connection->fd = open(connection->port, O_RDWR | O_NOCTTY | O_NONBLOCK)) == -1)
{
free(connection->port);
connection->port = NULL;
}
else
{
hasPossibleSerial = 1;
break;
}
}
}
if (hasPossibleSerial)
{
break;
}
}
if (!hasPossibleSerial)
{
fprintf(stderr, "Cannot find a serial device to open\n");
return -1;
}
}
/* set connection attributes */
connection->baudrate = baudrate;
connection->parity = 0;
if (_serial_setattr(connection) == -1)
{
goto error; /* possible bad behavior */
}
tcflush(connection->fd, TCIFLUSH);
tcflush(connection->fd, TCOFLUSH);
connection->connected = 1;
memset(connection->buffer, 0, SWBUFMAX);
memset(connection->readbuf, 0, SWREADMAX);
connection->readAvailable = 0;
printf("Connected to %s\n", connection->port);
return 0;
error:
fprintf(stderr, "Cannot connect to the device on %s\n", connection->port);
connection->connected = 0;
if (connection->fd != -1)
{
close(connection->fd);
}
connection->fd = -1;
if (connection->port)
{
free(connection->port);
}
connection->port = NULL;
return -1;
}
/** Method to update the readbuf of the serial communication,
* as well as the connection itself.
* @param connection
* the serial struct
* @note
* the packets will be read in the following format:
* data\n
*/
static void _serial_update(serial_t *connection)
{
int bytesRead;
int bytesStored;
unsigned char analyzeBuffer;
/* dynamically reconnect the device */
if (access(connection->port, F_OK) == -1)
{
if (connection->connected)
{
connection->connected = 0;
connection->fd = -1;
}
}
else
{
if (!connection->connected)
{
if ((connection->fd = open(connection->port, O_RDWR | O_NOCTTY | O_NDELAY)) != -1)
{
if (_serial_setattr(connection) == 0)
{
connection->connected = 1;
}
else
{
close(connection->fd);
connection->fd = -1;
}
}
}
}
if (!connection->connected)
{
return;
}
/* update buffer constantly (be careful of overflow!) */
analyzeBuffer = 0;
while ((bytesRead = read(connection->fd, tempbuf, SWREADMAX)) > 0)
{
if (bytesRead > 0)
{
analyzeBuffer = 1; /* turn on buffer analysis signal */
}
tempbuf[bytesRead] = '\0';
bytesStored = strlen(connection->buffer); /* no \0 */
while (bytesStored + bytesRead >= SWBUFMAX)
{
/* shorten it by only half of the readmax value */
bytesStored -= SWREADMAX / 2;
memmove(connection->buffer, &connection->buffer[SWREADMAX / 2], (bytesStored + 1) * sizeof(char));
}
strcat(connection->buffer, tempbuf);
}
if (analyzeBuffer)
{
char *start_index, *end_index;
size_t nbytes;
if ((end_index = strrchr(connection->buffer, '\n')))
{
end_index[0] = '\0';
end_index = &end_index[1];
start_index = strrchr(connection->buffer, '\n');
start_index = start_index ? &start_index[1] : connection->buffer;
nbytes = (size_t)end_index - (size_t)start_index;
memcpy(connection->readbuf, start_index, nbytes * sizeof(char));
connection->readbuf[nbytes + 1] = '\n'; /* put the \n back */
connection->readbuf[nbytes + 2] = '\0';
memmove(connection->buffer, end_index, (strlen(end_index) + 1) * sizeof(char));
connection->readAvailable = 1;
}
}
}
