118 lines
2.4 KiB
Go
118 lines
2.4 KiB
Go
package usb
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/*
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#include <libusb-1.0/libusb.h>
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int submit(struct libusb_transfer *xfer);
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*/
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import "C"
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import (
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"fmt"
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"log"
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"reflect"
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"time"
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"unsafe"
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)
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//export iso_callback
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func iso_callback(cptr unsafe.Pointer) {
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ch := *(*chan struct{})(cptr)
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close(ch)
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}
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func (end *endpoint) allocTransfer() *Transfer {
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// Use libusb_get_max_iso_packet_size ?
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const (
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iso_packets = 8 // 128 // 242
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packet_size = 2 * 960 // 1760
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)
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xfer := C.libusb_alloc_transfer(C.int(iso_packets))
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if xfer == nil {
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log.Printf("usb: transfer allocation failed?!")
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return nil
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}
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buf := make([]byte, iso_packets*packet_size)
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done := make(chan struct{}, 1)
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xfer.dev_handle = end.Device.handle
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xfer.endpoint = C.uchar(end.Address)
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xfer._type = C.LIBUSB_TRANSFER_TYPE_ISOCHRONOUS
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xfer.buffer = (*C.uchar)((unsafe.Pointer)(&buf[0]))
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xfer.length = C.int(len(buf))
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xfer.num_iso_packets = iso_packets
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C.libusb_set_iso_packet_lengths(xfer, packet_size)
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pkts := *(*[]C.struct_libusb_packet_descriptor)(unsafe.Pointer(&reflect.SliceHeader{
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Data: uintptr(unsafe.Pointer(&xfer.iso_packet_desc)),
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Len: iso_packets,
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Cap: iso_packets,
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}))
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t := &Transfer{
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xfer: xfer,
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pkts: pkts,
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done: done,
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buf: buf,
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}
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xfer.user_data = (unsafe.Pointer)(&t.done)
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return t
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}
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type Transfer struct {
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xfer *C.struct_libusb_transfer
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pkts []C.struct_libusb_packet_descriptor
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done chan struct{}
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buf []byte
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}
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func (t *Transfer) Submit(timeout time.Duration) error {
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log.Printf("iso: submitting %#v", t.xfer)
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t.xfer.timeout = C.uint(timeout / time.Millisecond)
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if errno := C.submit(t.xfer); errno < 0 {
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return usbError(errno)
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}
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return nil
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}
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func (t *Transfer) Wait(b []byte) (n int, err error) {
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select {
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case <-time.After(10 * time.Second):
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return 0, fmt.Errorf("wait timed out after 10s")
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case <-t.done:
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}
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n = int(t.xfer.actual_length)
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copy(b, ((*[1 << 16]byte)(unsafe.Pointer(t.xfer.buffer)))[:n])
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/*
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for i, pkt := range t.pkts {
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log.Printf("PACKET[%4d] - %#v", i, pkt)
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}*/
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return n, err
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}
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func (t *Transfer) Close() error {
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C.libusb_free_transfer(t.xfer)
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return nil
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}
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func isochronous_xfer(e *endpoint, buf []byte, timeout time.Duration) (int, error) {
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t := e.allocTransfer()
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defer t.Close()
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if err := t.Submit(timeout); err != nil {
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log.Printf("iso: xfer failed to submit: %s", err)
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return 0, err
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}
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n, err := t.Wait(buf)
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if err != nil {
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log.Printf("iso: xfer failed: %s", err)
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return 0, err
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}
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return n, err
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}
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