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// Copyright 2013 Google Inc. All rights reserved.
// Copyright 2016 the gousb Authors. 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 gousb
import (
"context"
"fmt"
"strings"
"time"
)
// EndpointAddress is a unique identifier for the endpoint, combining the endpoint number and direction.
type EndpointAddress uint8
// String implements the Stringer interface.
func (a EndpointAddress) String() string {
return fmt.Sprintf("0x%02x", uint8(a))
}
// EndpointDesc contains the information about an interface endpoint, extracted
// from the descriptor.
type EndpointDesc struct {
// Address is the unique identifier of the endpoint within the interface.
Address EndpointAddress
// Number represents the endpoint number. Note that the endpoint number is different from the
// address field in the descriptor - address 0x82 means endpoint number 2,
// with endpoint direction IN.
// The device can have up to two endpoints with the same number but with
// different directions.
Number int
// Direction defines whether the data is flowing IN or OUT from the host perspective.
Direction EndpointDirection
// MaxPacketSize is the maximum USB packet size for a single frame/microframe.
MaxPacketSize int
// TransferType defines the endpoint type - bulk, interrupt, isochronous.
TransferType TransferType
// PollInterval is the maximum time between transfers for interrupt and isochronous transfer,
// or the NAK interval for a control transfer. See endpoint descriptor bInterval documentation
// in the USB spec for details.
PollInterval time.Duration
// IsoSyncType is the isochronous endpoint synchronization type, as defined by USB spec.
IsoSyncType IsoSyncType
// UsageType is the isochronous or interrupt endpoint usage type, as defined by USB spec.
UsageType UsageType
}
// String returns the human-readable description of the endpoint.
func (e EndpointDesc) String() string {
ret := make([]string, 0, 3)
ret = append(ret, fmt.Sprintf("ep #%d %s (address %s) %s", e.Number, e.Direction, e.Address, e.TransferType))
switch e.TransferType {
case TransferTypeIsochronous:
ret = append(ret, fmt.Sprintf("- %s %s", e.IsoSyncType, e.UsageType))
case TransferTypeInterrupt:
ret = append(ret, fmt.Sprintf("- %s", e.UsageType))
}
ret = append(ret, fmt.Sprintf("[%d bytes]", e.MaxPacketSize))
return strings.Join(ret, " ")
}
type endpoint struct {
h *libusbDevHandle
InterfaceSetting
Desc EndpointDesc
ctx *Context
}
// String returns a human-readable description of the endpoint.
func (e *endpoint) String() string {
return e.Desc.String()
}
func (e *endpoint) transfer(ctx context.Context, buf []byte) (int, error) {
t, err := newUSBTransfer(e.ctx, e.h, &e.Desc, len(buf))
if err != nil {
return 0, err
}
defer t.free()
if e.Desc.Direction == EndpointDirectionOut {
copy(t.data(), buf)
}
if err := t.submit(); err != nil {
return 0, err
}
n, err := t.wait(ctx)
if e.Desc.Direction == EndpointDirectionIn {
copy(buf, t.data())
}
if err != nil {
return n, err
}
return n, nil
}
// InEndpoint represents an IN endpoint open for transfer.
// InEndpoint implements the io.Reader interface.
// For high-throughput transfers, consider creating a buffered read stream
// through InEndpoint.ReadStream.
type InEndpoint struct {
*endpoint
}
// Read reads data from an IN endpoint. Read returns number of bytes obtained
// from the endpoint. Read may return non-zero length even if
// the returned error is not nil (partial read).
// It's recommended to use buffer sizes that are multiples of
// EndpointDesc.MaxPacketSize to avoid overflows.
// When a USB device receives a read request, it doesn't know the size of the
// buffer and may send too much data in one packet to fit in the buffer.
// If that happens, Read will return an error signaling an overflow.
// See http://libusb.sourceforge.net/api-1.0/libusb_packetoverflow.html
// for more details.
func (e *InEndpoint) Read(buf []byte) (int, error) {
return e.transfer(context.Background(), buf)
}
// ReadContext reads data from an IN endpoint. ReadContext returns number of
// bytes obtained from the endpoint. ReadContext may return non-zero length
// even if the returned error is not nil (partial read).
// The passed context can be used to control the cancellation of the read. If
// the context is cancelled, ReadContext will cancel the underlying transfers,
// resulting in TransferCancelled error.
// It's recommended to use buffer sizes that are multiples of
// EndpointDesc.MaxPacketSize to avoid overflows.
// When a USB device receives a read request, it doesn't know the size of the
// buffer and may send too much data in one packet to fit in the buffer.
// If that happens, Read will return an error signaling an overflow.
// See http://libusb.sourceforge.net/api-1.0/libusb_packetoverflow.html
// for more details.
func (e *InEndpoint) ReadContext(ctx context.Context, buf []byte) (int, error) {
return e.transfer(ctx, buf)
}
// OutEndpoint represents an OUT endpoint open for transfer.
type OutEndpoint struct {
*endpoint
}
// Write writes data to an OUT endpoint. Write returns number of bytes comitted
// to the endpoint. Write may return non-zero length even if the returned error
// is not nil (partial write).
func (e *OutEndpoint) Write(buf []byte) (int, error) {
return e.transfer(context.Background(), buf)
}
// WriteContext writes data to an OUT endpoint. WriteContext returns number of
// bytes comitted to the endpoint. WriteContext may return non-zero length even
// if the returned error is not nil (partial write).
// The passed context can be used to control the cancellation of the write. If
// the context is cancelled, WriteContext will cancel the underlying transfers,
// resulting in TransferCancelled error.
func (e *OutEndpoint) WriteContext(ctx context.Context, buf []byte) (int, error) {
return e.transfer(ctx, buf)
}
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