1 files changed, 9 insertions, 5 deletions

diff --git a/src/dev/pktfifo.hh b/src/dev/pktfifo.hh
index 95d46fc76..ea5803026 100644
--- a/src/dev/pktfifo.hh
+++ b/src/dev/pktfifo.hh
@@ -80,6 +80,7 @@ class PacketFifo
 
     typedef std::list<PacketFifoEntry> fifo_list;
     typedef fifo_list::iterator iterator;
+    typedef fifo_list::const_iterator const_iterator;
 
   protected:
     std::list<PacketFifoEntry> fifo;
@@ -112,6 +113,9 @@ class PacketFifo
     iterator begin() { return fifo.begin(); }
     iterator end() { return fifo.end(); }
 
+    const_iterator begin() const { return fifo.begin(); }
+    const_iterator end() const { return fifo.end(); }
+
     EthPacketPtr front() { return fifo.begin()->packet; }
 
     bool push(EthPacketPtr ptr)
@@ -171,25 +175,25 @@ class PacketFifo
 
     bool copyout(void *dest, unsigned offset, unsigned len);
 
-    int countPacketsBefore(iterator i)
+    int countPacketsBefore(const_iterator i) const
     {
         if (i == fifo.end())
             return 0;
         return i->number - fifo.begin()->number;
     }
 
-    int countPacketsAfter(iterator i)
+    int countPacketsAfter(const_iterator i) const
     {
-        iterator end = fifo.end();
+        auto end = fifo.end();
         if (i == end)
             return 0;
         return (--end)->number - i->number;
     }
 
-    void check()
+    void check() const
     {
         unsigned total = 0;
-        for (iterator i = begin(); i != end(); ++i)
+        for (auto i = begin(); i != end(); ++i)
             total += i->packet->length + i->slack;
 
         if (total != _size)