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// Copyright 2013 Google Inc. All rights reserved.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
package usb
/*
#include "libusb.h"
int submit(struct libusb_transfer *xfer);
void print_xfer(struct libusb_transfer *xfer);
int extract_data(struct libusb_transfer *xfer, void *data, int max, unsigned char *status);
*/
import "C"
import (
"fmt"
"log"
"time"
"unsafe"
)
//export iso_callback
func iso_callback(cptr unsafe.Pointer) {
ch := *(*chan struct{})(cptr)
close(ch)
}
func (end *endpoint) allocTransfer() *Transfer {
// Use libusb_get_max_iso_packet_size ?
const (
iso_packets = 8 // 128 // 242
packet_size = 2 * 960 // 1760
)
xfer := C.libusb_alloc_transfer(C.int(iso_packets))
if xfer == nil {
log.Printf("usb: transfer allocation failed?!")
return nil
}
buf := make([]byte, iso_packets*packet_size)
done := make(chan struct{}, 1)
xfer.dev_handle = end.Device.handle
xfer.endpoint = C.uchar(end.Address)
xfer._type = C.LIBUSB_TRANSFER_TYPE_ISOCHRONOUS
xfer.buffer = (*C.uchar)((unsafe.Pointer)(&buf[0]))
xfer.length = C.int(len(buf))
xfer.num_iso_packets = iso_packets
C.libusb_set_iso_packet_lengths(xfer, packet_size)
/*
pkts := *(*[]C.struct_libusb_packet_descriptor)(unsafe.Pointer(&reflect.SliceHeader{
Data: uintptr(unsafe.Pointer(&xfer.iso_packet_desc)),
Len: iso_packets,
Cap: iso_packets,
}))
*/
t := &Transfer{
xfer: xfer,
done: done,
buf: buf,
}
xfer.user_data = (unsafe.Pointer)(&t.done)
return t
}
type Transfer struct {
xfer *C.struct_libusb_transfer
pkts []*C.struct_libusb_packet_descriptor
done chan struct{}
buf []byte
}
func (t *Transfer) Submit(timeout time.Duration) error {
//log.Printf("iso: submitting %#v", t.xfer)
t.xfer.timeout = C.uint(timeout / time.Millisecond)
if errno := C.submit(t.xfer); errno < 0 {
return usbError(errno)
}
return nil
}
func (t *Transfer) Wait(b []byte) (n int, err error) {
select {
case <-time.After(10 * time.Second):
return 0, fmt.Errorf("wait timed out after 10s")
case <-t.done:
}
// Non-iso transfers:
//n = int(t.xfer.actual_length)
//copy(b, ((*[1 << 16]byte)(unsafe.Pointer(t.xfer.buffer)))[:n])
//C.print_xfer(t.xfer)
/*
buf, offset := ((*[1 << 16]byte)(unsafe.Pointer(t.xfer.buffer))), 0
for i, pkt := range *t.pkts {
log.Printf("Type is %T", t.pkts)
n += copy(b[n:], buf[offset:][:pkt.actual_length])
offset += pkt.Length
if pkt.status != 0 && err == nil {
err = error(TransferStatus(pkt.status))
}
}
*/
var status uint8
n = int(C.extract_data(t.xfer, unsafe.Pointer(&b[0]), C.int(len(b)), (*C.uchar)(unsafe.Pointer(&status))))
if status != 0 {
err = TransferStatus(status)
}
return n, err
}
func (t *Transfer) Close() error {
C.libusb_free_transfer(t.xfer)
return nil
}
func isochronous_xfer(e *endpoint, buf []byte, timeout time.Duration) (int, error) {
t := e.allocTransfer()
defer t.Close()
if err := t.Submit(timeout); err != nil {
log.Printf("iso: xfer failed to submit: %s", err)
return 0, err
}
n, err := t.Wait(buf)
if err != nil {
log.Printf("iso: xfer failed: %s", err)
return 0, err
}
return n, err
}
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