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// Copyright 2017 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
func (e *endpoint) newStream(size, count int) (*stream, error) {
var ts []transferIntf
for i := 0; i < count; i++ {
t, err := newUSBTransfer(e.ctx, e.h, &e.Desc, size)
if err != nil {
for _, t := range ts {
t.free()
}
return nil, err
}
ts = append(ts, t)
}
return newStream(ts), nil
}
// NewStream prepares a new read stream that will keep reading data from
// the endpoint until closed or until an error or timeout is encountered.
// Size defines a buffer size for a single read transaction and count
// defines how many transactions should be active at any time.
// By keeping multiple transfers active at the same time, a Stream reduces
// the latency between subsequent transfers and increases reading throughput.
// Similarly to InEndpoint.Read, the size of the buffer should be a multiple
// of EndpointDesc.MaxPacketSize to avoid overflows, see documentation
// in InEndpoint.Read for more details.
func (e *InEndpoint) NewStream(size, count int) (*ReadStream, error) {
s, err := e.newStream(size, count)
if err != nil {
return nil, err
}
s.submitAll()
return &ReadStream{s: s}, nil
}
// NewStream prepares a new write stream that will write data in the
// background. Size defines a buffer size for a single write transaction and
// count defines how many transactions may be active at any time. By buffering
// the writes, a Stream reduces the latency between subsequent transfers and
// increases writing throughput.
func (e *OutEndpoint) NewStream(size, count int) (*WriteStream, error) {
s, err := e.newStream(size, count)
if err != nil {
return nil, err
}
return &WriteStream{s: s}, nil
}
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