Use pointer to generated FEC packet.

webrtc/modules/rtp_rtcp/source/forward_error_correction.cc

 /*
  *  Copyright (c) 2012 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 199 matching lines @@
     return;
   }
   uint8_t media_payload_length[2];
   const int num_mask_bytes = l_bit ? kMaskSizeLBitSet : kMaskSizeLBitClear;
   const uint16_t ulp_header_size =
       l_bit ? kUlpHeaderSizeLBitSet : kUlpHeaderSizeLBitClear;
   const uint16_t fec_rtp_offset =
       kFecHeaderSize + ulp_header_size - kRtpHeaderSize;
 
   for (int i = 0; i < num_fec_packets; ++i) {
+    Packet* const fec_packet = &generated_fec_packets_[i];
     PacketList::const_iterator media_list_it = media_packet_list.begin();
     uint32_t pkt_mask_idx = i * num_mask_bytes;
     uint32_t media_pkt_idx = 0;
     uint16_t fec_packet_length = 0;
     uint16_t prev_seq_num = ParseSequenceNumber((*media_list_it)->data);
     while (media_list_it != media_packet_list.end()) {
       // Each FEC packet has a multiple byte mask. Determine if this media
       // packet should be included in FEC packet i.
       if (packet_mask[pkt_mask_idx] & (1 << (7 - media_pkt_idx))) {
         Packet* media_packet = *media_list_it;
 
         // Assign network-ordered media payload length.
         ByteWriter<uint16_t>::WriteBigEndian(
             media_payload_length, media_packet->length - kRtpHeaderSize);
 
         fec_packet_length = media_packet->length + fec_rtp_offset;
         // On the first protected packet, we don't need to XOR.
-        if (generated_fec_packets_[i].length == 0) {
+        if (fec_packet->length == 0) {
           // Copy the first 2 bytes of the RTP header.
-          memcpy(generated_fec_packets_[i].data, media_packet->data, 2);
+          memcpy(fec_packet->data, media_packet->data, 2);
           // Copy the 5th to 8th bytes of the RTP header.
-          memcpy(&generated_fec_packets_[i].data[4], &media_packet->data[4], 4);
+          memcpy(&fec_packet->data[4], &media_packet->data[4], 4);
           // Copy network-ordered payload size.
-          memcpy(&generated_fec_packets_[i].data[8], media_payload_length, 2);
+          memcpy(&fec_packet->data[8], media_payload_length, 2);
 
           // Copy RTP payload, leaving room for the ULP header.
-          memcpy(
-              &generated_fec_packets_[i].data[kFecHeaderSize + ulp_header_size],
-              &media_packet->data[kRtpHeaderSize],
-              media_packet->length - kRtpHeaderSize);
+          memcpy(&fec_packet->data[kFecHeaderSize + ulp_header_size],
+                 &media_packet->data[kRtpHeaderSize],
+                 media_packet->length - kRtpHeaderSize);
         } else {
           // XOR with the first 2 bytes of the RTP header.
-          generated_fec_packets_[i].data[0] ^= media_packet->data[0];
-          generated_fec_packets_[i].data[1] ^= media_packet->data[1];
+          fec_packet->data[0] ^= media_packet->data[0];
+          fec_packet->data[1] ^= media_packet->data[1];
 
           // XOR with the 5th to 8th bytes of the RTP header.
           for (uint32_t j = 4; j < 8; ++j) {
-            generated_fec_packets_[i].data[j] ^= media_packet->data[j];
+            fec_packet->data[j] ^= media_packet->data[j];
           }
 
           // XOR with the network-ordered payload size.
-          generated_fec_packets_[i].data[8] ^= media_payload_length[0];
-          generated_fec_packets_[i].data[9] ^= media_payload_length[1];
+          fec_packet->data[8] ^= media_payload_length[0];
+          fec_packet->data[9] ^= media_payload_length[1];
 
           // XOR with RTP payload, leaving room for the ULP header.
           for (int32_t j = kFecHeaderSize + ulp_header_size;
                j < fec_packet_length; j++) {
-            generated_fec_packets_[i].data[j] ^=
-                media_packet->data[j - fec_rtp_offset];
+            fec_packet->data[j] ^= media_packet->data[j - fec_rtp_offset];
           }
         }
-        if (fec_packet_length > generated_fec_packets_[i].length) {
-          generated_fec_packets_[i].length = fec_packet_length;
+        if (fec_packet_length > fec_packet->length) {
+          fec_packet->length = fec_packet_length;
         }
       }
       media_list_it++;
       if (media_list_it != media_packet_list.end()) {
         uint16_t seq_num = ParseSequenceNumber((*media_list_it)->data);
         media_pkt_idx += static_cast<uint16_t>(seq_num - prev_seq_num);
         prev_seq_num = seq_num;
       }
       pkt_mask_idx += media_pkt_idx / 8;
       media_pkt_idx %= 8;
     }
-    RTC_DCHECK_GT(generated_fec_packets_[i].length, 0u)
+    RTC_DCHECK_GT(fec_packet->length, 0u)
         << "Packet mask is wrong or poorly designed.";
   }
 }
 
 int ForwardErrorCorrection::InsertZerosInBitMasks(
     const PacketList& media_packets,
     uint8_t* packet_mask,
     int num_mask_bytes,
     int num_fec_packets) {
   uint8_t* new_mask = NULL;
@@ skipping 122 matching lines @@
   //   |              mask cont. (present only when L = 1)             |
   //   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   PacketList::const_iterator media_list_it = media_packet_list.begin();
   Packet* media_packet = *media_list_it;
   assert(media_packet != NULL);
   int num_mask_bytes = l_bit ? kMaskSizeLBitSet : kMaskSizeLBitClear;
   const uint16_t ulp_header_size =
       l_bit ? kUlpHeaderSizeLBitSet : kUlpHeaderSizeLBitClear;
 
   for (int i = 0; i < num_fec_packets; ++i) {
+    Packet* const fec_packet = &generated_fec_packets_[i];
     // -- FEC header --
-    generated_fec_packets_[i].data[0] &= 0x7f;  // Set E to zero.
+    fec_packet->data[0] &= 0x7f;  // Set E to zero.
     if (l_bit == 0) {
-      generated_fec_packets_[i].data[0] &= 0xbf;  // Clear the L bit.
+      fec_packet->data[0] &= 0xbf;  // Clear the L bit.
     } else {
-      generated_fec_packets_[i].data[0] |= 0x40;  // Set the L bit.
+      fec_packet->data[0] |= 0x40;  // Set the L bit.
     }
     // Two byte sequence number from first RTP packet to SN base.
     // We use the same sequence number base for every FEC packet,
     // but that's not required in general.
-    memcpy(&generated_fec_packets_[i].data[2], &media_packet->data[2], 2);
+    memcpy(&fec_packet->data[2], &media_packet->data[2], 2);
 
     // -- ULP header --
     // Copy the payload size to the protection length field.
     // (We protect the entire packet.)
     ByteWriter<uint16_t>::WriteBigEndian(
-        &generated_fec_packets_[i].data[10],
-        generated_fec_packets_[i].length - kFecHeaderSize - ulp_header_size);
+        &fec_packet->data[10],
+        fec_packet->length - kFecHeaderSize - ulp_header_size);
 
     // Copy the packet mask.
-    memcpy(&generated_fec_packets_[i].data[12],
-           &packet_mask[i * num_mask_bytes], num_mask_bytes);
+    memcpy(&fec_packet->data[12], &packet_mask[i * num_mask_bytes],
+           num_mask_bytes);
   }
 }
 
 void ForwardErrorCorrection::ResetState(
     RecoveredPacketList* recovered_packet_list) {
   fec_packet_received_ = false;
 
   // Free the memory for any existing recovered packets, if the user hasn't.
   while (!recovered_packet_list->empty()) {
     delete recovered_packet_list->front();
@@ skipping 391 matching lines @@
   }
   InsertPackets(received_packet_list, recovered_packet_list);
   AttemptRecover(recovered_packet_list);
   return 0;
 }
 
 size_t ForwardErrorCorrection::PacketOverhead() {
   return kFecHeaderSize + kUlpHeaderSizeLBitSet;
 }
 }  // namespace webrtc