update src/device.c.
Correct "rt_device_read()" and "rt_device_write()" comments error. They should return 0 on fail, otherwise negative.
@@ -339,7 +339,7 @@ RTM_EXPORT(rt_device_close);
* @param buffer the data buffer to save read data
* @param size the size of buffer
*
- * @return the actually read size on successful, otherwise negative returned.
+ * @return the actually read size on successful, otherwise zero returned.
*
* @note since 0.4.0, the unit of size/pos is a block for block device.
*/
@@ -378,7 +378,7 @@ RTM_EXPORT(rt_device_read);
* @param buffer the data buffer to be written to device
* @param size the size of buffer
*
- * @return the actually written size on successful, otherwise negative returned.
+ * @return the actually written size on successful, otherwise zero returned.
*
* @note since 0.4.0, the unit of size/pos is a block for block device.
*/
