inorder: define iterator for resource schedules

resource skeds are divided into two parts: front end (all insts) and back end (inst. specific)
each of those are implemented as separate lists,  so this iterator wraps around
the traditional list iterator so that an instruction can walk it's schedule but seamlessly
transfer from front end to back end when necessary

src/cpu/inorder/resource_sked.hh

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2010 The Regents of The University of Michigan
+ * Copyright (c) 2010-2011 The Regents of The University of Michigan
  * All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
@@ -34,6 +34,7 @@
 
 #include <vector>
 #include <list>
+#include <cstdlib>
 
 /** ScheduleEntry class represents a single function that an instruction
     wants to do at any pipeline stage. For example, if an instruction
@@ -86,6 +87,7 @@ class ScheduleEntry {
 class ResourceSked {
   public:
     typedef std::list<ScheduleEntry*>::iterator SkedIt;
+    typedef std::vector<std::list<ScheduleEntry*> > StageList;
 
     ResourceSked();
 
@@ -103,6 +105,12 @@ class ResourceSked {
     /** Is the schedule empty? */
     bool empty();
 
+    /** Beginning Entry of this schedule */
+    SkedIt begin();
+
+    /** Ending Entry of this schedule */
+    SkedIt end();
+
     /** What is the next task for this instruction schedule? */
     ScheduleEntry* top();
 
@@ -120,14 +128,19 @@ class ResourceSked {
     /** Print what's left on the instruction schedule */
     void print();
 
+    StageList *getStages()
+    {
+        return &stages;
+    }
+
   private:
     /** Current Schedule Entry Pointer */
     SkedIt curSkedEntry;
 
-    /** The Resource Schedule: Resized to Number of Stages in
-        the constructor
+    /** The Stage-by-Stage Resource Schedule:
+        Resized to Number of Stages in the constructor
     */
-    std::vector<std::list<ScheduleEntry*> > sked;
+    StageList stages;
 
     /** Find a place to insert the instruction using  the
         schedule entries priority
@@ -141,4 +154,126 @@ class ResourceSked {
                              int sked_cmd, int sked_cmd_idx = -1);
 };
 
+/** Wrapper class around the SkedIt iterator in the Resource Sked so that
+    we can use ++ operator to automatically go to the next available
+    resource schedule entry but otherwise maintain same functionality
+    as a normal iterator.
+*/
+class RSkedIt
+{
+  public:
+    RSkedIt()
+        : curStage(0), numStages(0)
+    { }
+
+
+    /** init() must be called before the use of any other member
+        in the RSkedIt class.
+    */
+    void init(ResourceSked* rsked)
+    {
+        stages = rsked->getStages();
+        numStages = stages->size();
+    }
+
+    /* Update the encapsulated "myIt" iterator, but only
+       update curStage/curStage_end if the iterator is valid.
+       The iterator could be invalid in the case where
+       someone is saving the end of a list (i.e. std::list->end())
+    */
+    RSkedIt operator=(ResourceSked::SkedIt const &rhs)
+    {
+        myIt = rhs;
+        if (myIt != (*stages)[numStages-1].end()) {
+            curStage = (*myIt)->stageNum;
+            curStage_end = (*stages)[curStage].end();
+        }
+        return *this;
+    }
+
+    /** Increment to the next entry in current stage.
+        If no more entries then find the next stage that has
+        resource schedule to complete.
+        If no more stages, then return the end() iterator from
+        the last stage to indicate we are done.
+    */
+    RSkedIt &operator++(int unused)
+    {
+        if (++myIt == curStage_end) {
+            curStage++;
+            while (curStage < numStages) {
+                if ((*stages)[curStage].empty()) {
+                    curStage++;
+                } else {
+                    myIt = (*stages)[curStage].begin();
+                    curStage_end = (*stages)[curStage].end();
+                    return *this;
+                }
+            }
+
+            myIt = (*stages)[numStages - 1].end();
+        }
+
+        return *this;
+    }
+
+    /** The "pointer" operator can be used on a RSkedIt and it
+        will use the encapsulated iterator
+    */
+    ScheduleEntry* operator->()
+    {
+        return *myIt;
+    }
+
+    /** Dereferencing a RSKedIt will access the encapsulated
+        iterator
+    */
+    ScheduleEntry* operator*()
+    {
+        return *myIt;
+    }
+
+    /** Equality for RSkedIt only compares the "myIt" iterators,
+        as the other members are just ancillary
+    */
+    bool operator==(RSkedIt const &rhs)
+    {
+        return this->myIt == rhs.myIt;
+    }
+
+    /** Inequality for RSkedIt only compares the "myIt" iterators,
+        as the other members are just ancillary
+    */
+    bool operator!=(RSkedIt const &rhs)
+    {
+        return this->myIt != rhs.myIt;
+    }
+
+    /* The == and != operator overloads should be sufficient
+       here if need otherwise direct access to the schedule
+       iterator, then this can be used */
+    ResourceSked::SkedIt getIt()
+    {
+        return myIt;
+    }
+
+  private:
+    /** Schedule Iterator that this class is encapsulating */
+    ResourceSked::SkedIt myIt;
+
+    /** Ptr to resource schedule that the 'myIt' iterator
+        belongs to
+    */
+    ResourceSked::StageList *stages;
+
+    /**  The last iterator in the current stage. */
+    ResourceSked::SkedIt curStage_end;
+
+    /** Current Stage that "myIt" refers to. */
+    int curStage;
+
+    /** Number of stages in the "*stages" object. */
+    int numStages;
+};
+
 #endif //__CPU_INORDER_RESOURCE_SKED_HH__