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/*
*------------------------------------------------------------------
* Copyright (c) 2020 Cisco and/or its affiliates.
* 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 memif
// WritePacket writes one packet to the shared memory and
// returns the number of bytes written
func (q *Queue) WritePacket(pkt []byte) int {
var mask int = q.ring.size - 1
var slot int
var nFree uint16
var packetBufferSize int = int(q.i.run.PacketBufferSize)
if q.i.args.IsMaster {
slot = q.readTail()
nFree = uint16(q.readHead() - slot)
} else {
slot = q.readHead()
nFree = uint16(q.ring.size - slot + q.readTail())
}
if nFree == 0 {
q.interrupt()
return 0
}
// copy descriptor from shm
desc := newDescBuf()
q.getDescBuf(slot&mask, desc)
// reset flags
desc.setFlags(0)
// reset length
if q.i.args.IsMaster {
packetBufferSize = desc.getLength()
}
desc.setLength(0)
offset := desc.getOffset()
// write packet into memif buffer
n := copy(q.i.regions[desc.getRegion()].data[offset:offset+packetBufferSize], pkt[:])
desc.setLength(n)
for n < len(pkt) {
nFree--
if nFree == 0 {
q.interrupt()
return 0
}
desc.setFlags(descFlagNext)
q.putDescBuf(slot&mask, desc)
slot++
// copy descriptor from shm
q.getDescBuf(slot&mask, desc)
// reset flags
desc.setFlags(0)
// reset length
if q.i.args.IsMaster {
packetBufferSize = desc.getLength()
}
desc.setLength(0)
offset := desc.getOffset()
tmp := copy(q.i.regions[desc.getRegion()].data[offset:offset+packetBufferSize], pkt[:])
desc.setLength(tmp)
n += tmp
}
// copy descriptor to shm
q.putDescBuf(slot&mask, desc)
slot++
if q.i.args.IsMaster {
q.writeTail(slot)
} else {
q.writeHead(slot)
}
q.interrupt()
return n
}
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