1 files changed, 99 insertions, 0 deletions
diff --git a/cpu/beta_cpu/2bit_local_pred.hh b/cpu/beta_cpu/2bit_local_pred.hh
new file mode 100644
index 000000000..32a7972d0
--- /dev/null
+++ b/cpu/beta_cpu/2bit_local_pred.hh
@@ -0,0 +1,99 @@
+#ifndef __2BIT_LOCAL_PRED_HH__
+#define __2BIT_LOCAL_PRED_HH__
+
+// For Addr type.
+#include "arch/alpha/isa_traits.hh"
+
+class DefaultBP
+{
+  public:
+    /**
+     * Default branch predictor constructor.
+     */
+    DefaultBP(unsigned localPredictorSize, unsigned localCtrBits,
+              unsigned instShiftAmt);
+
+    /**
+     * Looks up the given address in the branch predictor and returns
+     * a true/false value as to whether it is taken.
+     * @param branch_addr The address of the branch to look up.
+     * @return Whether or not the branch is taken.
+     */
+    bool lookup(Addr &branch_addr);
+
+    /**
+     * Updates the branch predictor with the actual result of a branch.
+     * @param branch_addr The address of the branch to update.
+     * @param taken Whether or not the branch was taken.
+     */
+    void update(Addr &branch_addr, bool taken);
+
+  private:
+
+    inline bool getPrediction(uint8_t &count);
+
+    inline unsigned getLocalIndex(Addr &PC);
+
+    /**
+     * Private counter class for the internal saturating counters.
+     * Implements an n bit saturating counter and provides methods to
+     * increment, decrement, and read it.
+     * @todo Consider making this something that more closely mimics a
+     * built in class so you can use ++ or --.
+     */
+    class SatCounter
+    {
+      public:
+        /**
+         * Constructor for the counter.
+         * @param bits How many bits the counter will have.
+         */
+        SatCounter(unsigned bits);
+
+        /**
+         * Constructor for the counter.
+         * @param bits How many bits the counter will have.
+         * @param initial_val Starting value for each counter.
+         */
+        SatCounter(unsigned bits, unsigned initial_val);
+
+        /**
+         * Increments the counter's current value.
+         */
+        void increment();
+
+        /**
+         * Decrements the counter's current value.
+         */
+        void decrement();
+
+        /**
+         * Read the counter's value.
+         */
+        uint8_t read()
+        {
+            return counter;
+        }
+
+      private:
+        uint8_t maxVal;
+        uint8_t counter;
+    };
+
+    /** Array of counters that make up the local predictor. */
+    SatCounter *localCtrs;
+
+    /** Size of the local predictor. */
+    unsigned localPredictorSize;
+
+    /** Number of bits of the local predictor's counters. */
+    unsigned localCtrBits;
+
+    /** Number of bits to shift the PC when calculating index. */
+    unsigned instShiftAmt;
+
+    /** Mask to get index bits. */
+    unsigned indexMask;
+};
+
+#endif // __2BIT_LOCAL_PRED_HH__