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uart: add capability to check if data can be read from device

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Signed-off-by: Jon Trulson <jtrulson@ics.com>
Signed-off-by: Brendan Le Foll <brendan.le.foll@intel.com>
This commit is contained in:
Jon Trulson
2015-04-29 16:13:07 -06:00
committed by Thomas Ingleby
parent cf14939cca
commit c30457e434
3 changed files with 60 additions and 0 deletions
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36
src/uart/uart.c
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@@ -204,3 +204,39 @@ mraa_uart_write(mraa_uart_context dev, char *buf, size_t len)
return write(dev->fd, buf, len);
}
mraa_boolean_t
mraa_uart_data_available(mraa_uart_context dev, unsigned int millis)
{
if (!dev) {
syslog(LOG_ERR, "uart: data_available: write context is NULL");
return 0;
}
if (dev->fd < 0) {
syslog(LOG_ERR, "uart: port is not open");
return 0;
}
struct timeval timeout;
if (millis == 0) {
// no waiting
timeout.tv_sec = 0;
timeout.tv_usec = 0;
}
else {
timeout.tv_sec = millis / 1000;
timeout.tv_usec = (millis % 1000) * 1000;
}
fd_set readfds;
FD_ZERO(&readfds);
FD_SET(dev->fd, &readfds);
if (select(dev->fd + 1, &readfds, NULL, NULL, &timeout) > 0)
return 1; // data is ready
else
return 0;
}