Move fragments into interleaver instead of copying them

3 files changed, 26 insertions, 28 deletions

diff --git a/src/DabMultiplexer.cpp b/src/DabMultiplexer.cpp
index 6d3a51e..b5f1933 100644
--- a/src/DabMultiplexer.cpp
+++ b/src/DabMultiplexer.cpp
@@ -714,9 +714,7 @@ void DabMultiplexer::mux_frame(std::vector<std::shared_ptr<DabOutput> >& outputs
             vector<edi::PFTFragment> edi_fragments = edi_pft.Assemble(edi_afpacket);
 
             if (edi_conf.interleaver_enabled()) {
-                edi_interleaver.PushFragments(edi_fragments);
-
-                edi_fragments = edi_interleaver.Interleave();
+                edi_fragments = edi_interleaver.Interleave(edi_fragments);
             }
 
             // Send over ethernet
diff --git a/src/dabOutput/edi/Interleaver.cpp b/src/dabOutput/edi/Interleaver.cpp
index ab3a5fc..83f2512 100644
--- a/src/dabOutput/edi/Interleaver.cpp
+++ b/src/dabOutput/edi/Interleaver.cpp
@@ -38,34 +38,32 @@ void Interleaver::SetLatency(size_t latency_frames)
     m_latency = latency_frames;
 }
 
-void Interleaver::PushFragments(const std::vector<PFTFragment> &fragments)
+Interleaver::fragment_vec Interleaver::Interleave(fragment_vec &fragments)
 {
+    m_fragment_count = fragments.size();
+
     // Create vectors containing Fcount*latency fragments in total
     // and store them into the deque
     if (m_buffer.empty()) {
-        m_buffer.push_back(fragments);
+        m_buffer.emplace_back();
     }
-    else {
-        auto& last_buffer = m_buffer.back();
 
-        const bool last_buffer_is_complete =
-                (last_buffer.size() >= m_fragment_count * m_latency);
+    auto& last_buffer = m_buffer.back();
 
-        if (last_buffer_is_complete) {
-            m_buffer.push_back(fragments);
-        }
-        else {
-            std::copy(fragments.begin(), fragments.end(),
-                    std::back_inserter(last_buffer));
-        }
+    const bool last_buffer_is_complete =
+            (last_buffer.size() >= m_fragment_count * m_latency);
+
+    if (last_buffer_is_complete) {
+        m_buffer.emplace_back();
+        last_buffer = m_buffer.back();
     }
 
-    m_fragment_count = fragments.size();
-}
+    std::move(fragments.begin(), fragments.end(),
+            std::back_inserter(last_buffer));
 
-std::vector<PFTFragment> Interleaver::Interleave()
-{
-    std::vector<PFTFragment> fragments;
+    fragments.clear();
+
+    std::vector<PFTFragment> interleaved_frags;
 
     while ( not m_buffer.empty() and
             (m_buffer.front().size() >= m_fragment_count * m_latency)) {
@@ -90,7 +88,7 @@ std::vector<PFTFragment> Interleaver::Interleave()
 
         for (size_t i = 0; i < m_fragment_count; i++) {
             const size_t ix = m_interleave_offset + m_fragment_count * m_stride;
-            fragments.push_back(first_buffer.at(ix));
+            interleaved_frags.push_back(first_buffer.at(ix));
 
             m_stride += 1;
             if (m_stride >= m_latency) {
@@ -106,7 +104,7 @@ std::vector<PFTFragment> Interleaver::Interleave()
         }
     }
 
-    return fragments;
+    return interleaved_frags;
 }
 
 }
diff --git a/src/dabOutput/edi/Interleaver.h b/src/dabOutput/edi/Interleaver.h
index 1a2e26d..51a584f 100644
--- a/src/dabOutput/edi/Interleaver.h
+++ b/src/dabOutput/edi/Interleaver.h
@@ -43,23 +43,25 @@ namespace edi {
 
 class Interleaver {
     public:
+        using fragment_vec = std::vector<PFTFragment>;
+
         /* Configure the interleaver to use latency_frames number of AF
          * packets for interleaving. Total delay through the interleaver
          * will be latency_frames * 24ms
          */
         void SetLatency(size_t latency_frames);
 
-        /* Push the fragments for an AF Packet into the interleaver */
-        void PushFragments(const std::vector< PFTFragment > &fragments);
-
-        std::vector< PFTFragment > Interleave(void);
+        /* Move the fragments for an AF Packet into the interleaver and
+         * return interleaved fragments to be transmitted.
+         */
+        fragment_vec Interleave(fragment_vec &fragments);
 
     private:
         size_t m_latency = 0;
         size_t m_fragment_count = 0;
         size_t m_interleave_offset = 0;
         size_t m_stride = 0;
-        std::deque<std::vector<PFTFragment> > m_buffer;
+        std::deque<fragment_vec> m_buffer;
 };
 
 }