Function uart_irq_rx_ready 

pub unsafe extern "C" fn uart_irq_rx_ready(dev: *const device) -> i32

@brief Check if UART RX buffer has a received char

@details Check if UART RX buffer has at least one pending character (i.e. uart_fifo_read() will succeed and return non-zero). This function must be called in a UART interrupt handler, or its result is undefined. Before calling this function in the interrupt handler, uart_irq_update() must be called once per the handler invocation. It’s unspecified whether condition as returned by this function is level- or edge- triggered (i.e. if this function returns true when RX FIFO is non-empty, or when a new char was received since last call to it). See description of uart_fifo_read() for implication of this.

@param dev UART device instance.

@retval 1 If a received char is ready. @retval 0 If a received char is not ready. @retval -ENOSYS If this function is not implemented. @retval -ENOTSUP If API is not enabled.