Function rx_callback

src/usb_serial.rs:137–163

(packet: &UsbEndpointTransferDescriptor)

}

fn rx_callback(packet: &UsbEndpointTransferDescriptor) {
    if unsafe { CONFIGURED } == false {
        return;
    }

    let qh = usb_get_queuehead(CDC_RX_ENDPOINT as usize, false);
    let len = (RX_BUFFER_SIZE as u32) - (packet.status >> 16) & 0x7FFF;

    // // Read the bytes
    for index in 0..len {
        unsafe {
            BUFFER.enqueue(RX_BUFFER.bytes[index as usize]);
        }
    }

    // If the queueheads have been reset, let's
    // re-initialize it all.
    //
    // IDK if this is a good idea??
    // What is the benefit of this vs. just having 1 descriptor?
    // I'm assuming multiple pages will give us some amount of
    // concurrency resilience but not really sure.
    if qh.first_transfer == qh.last_transfer && qh.first_transfer == 0 {
        // Process
        rx_queue_transfer();
    }
}

/// Returns how many bytes are available to read from
/// the buffer.