/// <summary>
/// Allocate a libusb transfer with a specified number of isochronous packet descriptors
/// </summary>
/// <remarks>
/// <para>The returned transfer is pre-initialized for you. When the new transfer is no longer needed, it should be freed with <see cref="Free"/>.</para>
/// <para>Transfers intended for non-isochronous endpoints (e.g. control, bulk, interrupt) should specify an iso_packets count of zero.</para>
/// <para>For transfers intended for isochronous endpoints, specify an appropriate number of packet descriptors to be allocated as part of the transfer. The returned transfer is not specially initialized for isochronous I/O; you are still required to set the <see cref="MonoUsbTransfer.NumIsoPackets"/> and <see cref="MonoUsbTransfer.Type"/> fields accordingly.</para>
/// <para>It is safe to allocate a transfer with some isochronous packets and then use it on a non-isochronous endpoint. If you do this, ensure that at time of submission, <see cref="MonoUsbTransfer.NumIsoPackets"/> is 0 and that type is set appropriately.</para>
/// <note title="Libusb-1.0 API Note:" type="cpp">
/// <see cref="Alloc"/> is roughly equivalent to
/// <a href="http://libusb.sourceforge.net/api-1.0/group__asyncio.html#ga13cc69ea40c702181c430c950121c000">libusb_alloc_transfer()</a>.
/// </note>
/// </remarks>
/// <param name="numIsoPackets">number of isochronous packet descriptors to allocate.</param>
/// <returns>A newly allocated <see cref="MonoUsbTransfer"/>.</returns>
/// <exception cref="OutOfMemoryException">If the transfer was not allocated.</exception>
public static MonoUsbTransfer Alloc(int numIsoPackets)
{
IntPtr p = MonoUsbApi.AllocTransfer(numIsoPackets);
if (p == IntPtr.Zero)
{
throw new OutOfMemoryException("AllocTransfer");
}
return(new MonoUsbTransfer(p));
}
/// <summary>
/// Allocate a libusb transfer with a specified number of isochronous packet descriptors
/// </summary>
/// <remarks>
/// <para>The transfer is pre-initialized for you. When the new transfer is no longer needed, it should be freed with <see cref="Free"/>.</para>
/// <para>Transfers intended for non-isochronous endpoints (e.g. control, bulk, interrupt) should specify an iso_packets count of zero.</para>
/// <para>For transfers intended for isochronous endpoints, specify an appropriate number of packet descriptors to be allocated as part of the transfer. The returned transfer is not specially initialized for isochronous I/O; you are still required to set the <see cref="MonoUsbTransfer.NumIsoPackets"/> and <see cref="MonoUsbTransfer.Type"/> fields accordingly.</para>
/// <para>It is safe to allocate a transfer with some isochronous packets and then use it on a non-isochronous endpoint. If you do this, ensure that at time of submission, <see cref="MonoUsbTransfer.NumIsoPackets"/> is 0 and that type is set appropriately.</para>
/// </remarks>
/// <param name="numIsoPackets">number of isochronous packet descriptors to allocate.</param>
public MonoUsbTransfer(int numIsoPackets)
{
handle = MonoUsbApi.AllocTransfer(numIsoPackets);
}