1 files changed, 143 insertions, 0 deletions
diff --git a/src/intersim/arbiter.cpp b/src/intersim/arbiter.cpp
new file mode 100644
index 0000000..7225b9b
--- /dev/null
+++ b/src/intersim/arbiter.cpp
@@ -0,0 +1,143 @@
+#include "booksim.hpp"
+#include <assert.h>
+
+#include "arbiter.hpp"
+
+
+Arbiter::Arbiter( const Configuration &,
+                  Module *parent, const string& name,
+                  int inputs )
+: Module( parent, name ), _inputs( inputs )
+{
+}
+
+Arbiter::~Arbiter( )
+{
+}
+
+void Arbiter::Clear( )
+{
+   _requests.clear( );
+}
+
+void Arbiter::AddRequest( int in, int label, int pri )
+{
+   sRequest r;
+   list<sRequest>::iterator insert_point;
+
+   r.in = in; r.label = label; r.pri = pri;
+
+   insert_point = _requests.begin( );
+   while ( ( insert_point != _requests.end( ) ) &&
+           ( insert_point->in < in ) ) {
+      insert_point++;
+   }
+
+   bool del = false;
+   bool add = true;
+
+   // For consistant behavior, delete the existing request
+   // if it is for the same input and has a higher
+   // priority
+
+   if ( ( insert_point != _requests.end( ) ) &&
+        ( insert_point->in == in ) ) {
+      if ( insert_point->pri < pri ) {
+         del = true;
+      } else {
+         add = false;
+      }
+   }
+
+   if ( add ) {
+      _requests.insert( insert_point, r );
+   }
+
+   if ( del ) {
+      _requests.erase( insert_point );
+   }
+}
+
+void Arbiter::RemoveRequest( int in, int label )
+{
+   list<sRequest>::iterator erase_point;
+
+   erase_point = _requests.begin( );
+   while ( ( erase_point != _requests.end( ) ) &&
+           ( erase_point->in < in ) ) {
+      erase_point++;
+   }
+
+   assert( erase_point != _requests.end( ) );
+   _requests.erase( erase_point );
+}
+
+int Arbiter::Match( ) const
+{
+   return _match;
+}
+
+//==================================================
+// PriorityArbiter
+//==================================================
+
+PriorityArbiter::PriorityArbiter( const Configuration &config,
+                                  Module *parent, const string& name,
+                                  int inputs ) 
+: Arbiter( config, parent, name, inputs )
+{
+   _rr_ptr = 0;
+}
+
+PriorityArbiter::~PriorityArbiter( )
+{
+}
+
+void PriorityArbiter::Arbitrate( )
+{
+   list<sRequest>::iterator p;
+
+   int max_index, max_pri;
+   bool wrapped;
+
+   if ( _requests.begin( ) != _requests.end( ) ) {
+      // A round-robin arbiter between input requests
+      p = _requests.begin( );
+      while ( ( p != _requests.end( ) ) &&
+              ( p->in < _rr_ptr ) ) {
+         p++;
+      }
+
+      max_index = -1;
+      max_pri   = 0;
+
+      wrapped = false;
+      while ( (!wrapped) || ( p->in < _rr_ptr ) ) {
+         if ( p == _requests.end( ) ) {
+            if ( wrapped ) {
+               break;
+            }
+            // p is valid here because empty lists
+            // are skipped (above)
+            p = _requests.begin( );
+            wrapped = true;
+         }
+
+         // check if request is the highest priority so far
+         if ( ( p->pri > max_pri ) || ( max_index == -1 ) ) {
+            max_pri   = p->pri;
+            max_index = p->in;
+         }
+
+         p++;
+      }   
+
+      _match = max_index; // -1 for no match
+      if ( _match != -1 ) {
+         _rr_ptr = ( _match + 1 ) % _inputs;
+      }
+
+   } else {
+      _match = -1;
+   }
+}