Add FlexFEC header formatters. (pt. 5)

webrtc/modules/rtp_rtcp/source/ulpfec_header_reader_writer.cc

 /*
  *  Copyright (c) 2016 The WebRTC project authors. All Rights Reserved.
  *
  *  Use of this source code is governed by a BSD-style license
  *  that can be found in the LICENSE file in the root of the source
  *  tree. An additional intellectual property rights grant can be found
  *  in the file PATENTS.  All contributing project authors may
  *  be found in the AUTHORS file in the root of the source tree.
  */
 
@@ skipping 81 matching lines @@
 size_t UlpfecHeaderWriter::MinPacketMaskSize(const uint8_t* packet_mask,
                                              size_t packet_mask_size) const {
   return packet_mask_size;
 }
 
 size_t UlpfecHeaderWriter::FecHeaderSize(size_t packet_mask_size) const {
   return UlpfecHeaderSize(packet_mask_size);
 }
 
 void UlpfecHeaderWriter::FinalizeFecHeader(
+    uint32_t media_ssrc,

[danilchap, 2016/09/21 11:17:56]

there is construct
uint32_t /* media_ssrc */
to stress variable is unused. Not widely used in webrtc code, but recommended by
base google style
https://google.github.io/styleguide/cppguide.html#Function_Declarations_and_D...

[brandtr, 2016/09/21 11:43:28]

Done.

     uint16_t seq_num_base,
     const uint8_t* packet_mask,
     size_t packet_mask_size,
     ForwardErrorCorrection::Packet* fec_packet) const {
   // Set E bit to zero.
   fec_packet->data[0] &= 0x7f;
   // Set L bit based on packet mask size. (Note that the packet mask
   // can only take on two discrete values.)
   bool l_bit = (packet_mask_size == kUlpfecPacketMaskSizeLBitSet);
   if (l_bit) {
     fec_packet->data[0] |= 0x40;  // Set the L bit.
   } else {
     RTC_DCHECK_EQ(packet_mask_size, kUlpfecPacketMaskSizeLBitClear);
     fec_packet->data[0] &= 0xbf;  // Clear the L bit.
   }
   // Copy length recovery field from temporary location.
   memcpy(&fec_packet->data[8], &fec_packet->data[2], 2);
   // Write sequence number base.
   ByteWriter<uint16_t>::WriteBigEndian(&fec_packet->data[2], seq_num_base);
   // Protection length is set to entire packet. (This is not
   // required in general.)
   const size_t fec_header_size = FecHeaderSize(packet_mask_size);
   ByteWriter<uint16_t>::WriteBigEndian(&fec_packet->data[10],
                                        fec_packet->length - fec_header_size);
   // Copy the packet mask.
   memcpy(&fec_packet->data[12], packet_mask, packet_mask_size);
 }
 
 }  // namespace webrtc