((*((SERIAL_T)->ops->noflush_set_tty_state)) \
((SERIAL_T), (NEW_TTYSTATE), (OLD_TTYSTATE)))
-/* Read one char from the serial device with TIMEOUT seconds timeout.
- Returns char if ok, else one of the following codes. Note that all
- error codes are guaranteed to be < 0. */
+/* Read one char from the serial device with TIMEOUT seconds to wait
+ or -1 to wait forever. Use timeout of 0 to effect a poll. Returns
+ char if ok, else one of the following codes. Note that all error
+ codes are guaranteed to be < 0. */
#define SERIAL_ERROR -1 /* General error, see errno for details */
#define SERIAL_TIMEOUT -2