f13728c6e1
an isochronous endpoint. Use MaxIsoPacket as the iso packet size when preparing the iso transfer.
147 lines
3.5 KiB
Go
147 lines
3.5 KiB
Go
// Copyright 2013 Google Inc. All rights reserved.
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//
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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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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void print_xfer(struct libusb_transfer *xfer);
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int extract_data(struct libusb_transfer *xfer, void *data, int max, unsigned char *status);
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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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"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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const (
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iso_packets = 8 // 128 // 242
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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*end.EndpointInfo.MaxIsoPacket)
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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, C.uint(end.EndpointInfo.MaxIsoPacket))
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/*
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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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*/
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t := &Transfer{
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xfer: xfer,
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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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// Non-iso transfers:
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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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//C.print_xfer(t.xfer)
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/*
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buf, offset := ((*[1 << 16]byte)(unsafe.Pointer(t.xfer.buffer))), 0
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for i, pkt := range *t.pkts {
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log.Printf("Type is %T", t.pkts)
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n += copy(b[n:], buf[offset:][:pkt.actual_length])
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offset += pkt.Length
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if pkt.status != 0 && err == nil {
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err = error(TransferStatus(pkt.status))
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}
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}
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*/
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var status uint8
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n = int(C.extract_data(t.xfer, unsafe.Pointer(&b[0]), C.int(len(b)), (*C.uchar)(unsafe.Pointer(&status))))
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if status != 0 {
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err = TransferStatus(status)
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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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