gomemif: introduce gomemif

golang native memif driver

Type: feature

Signed-off-by: Jakub Grajciar <jgrajcia@cisco.com>
Change-Id: I693156a44011c80025245d25134f5bf5db6eba82
Signed-off-by: Jakub Grajciar <jgrajcia@cisco.com>

1 files changed, 95 insertions, 0 deletions

diff --git a/extras/gomemif/memif/packet_writer.go b/extras/gomemif/memif/packet_writer.go
new file mode 100644
index 00000000000..702044f4b49
--- /dev/null
+++ b/extras/gomemif/memif/packet_writer.go
@@ -0,0 +1,95 @@
+/*
+ *------------------------------------------------------------------
+ * 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
+}