First version of streaming transfers.

usb/transfer.go

@@ -33,7 +33,7 @@ type usbTransfer struct {
 	// done is blocking until the transfer is complete and data and transfer
 	// status are available.
 	done chan struct{}
-	// submitted is true if this transfer was passed to libusb through submit()
+	// submitted is true if submit() was called on this transfer.
 	submitted bool
 }
 
@@ -110,6 +110,11 @@ func (t *usbTransfer) free() error {
 	return nil
 }
 
+// data returns the slice containing transfer buffer.
+func (t *usbTransfer) data() []byte {
+	return t.buf
+}
+
 // newUSBTransfer allocates a new transfer structure for communication with a
 // given device/endpoint, with buf as the underlying transfer buffer.
 func newUSBTransfer(dev *libusbDevHandle, ei *EndpointInfo, buf []byte, timeout time.Duration) (*usbTransfer, error) {