1 files changed, 144 insertions, 0 deletions
diff --git a/cpu/beta_cpu/decode.hh b/cpu/beta_cpu/decode.hh
new file mode 100644
index 000000000..64e87290e
--- /dev/null
+++ b/cpu/beta_cpu/decode.hh
@@ -0,0 +1,144 @@
+// Todo:
+// Add a couple of the branch fields to DynInst.  Figure out where DynInst
+// should try to compute the target of a PC-relative branch.  Try to avoid
+// having so many returns within the code.
+// Fix up squashing too, as it's too
+// dependent upon the iew stage continually telling it to squash.
+
+#ifndef __SIMPLE_DECODE_HH__
+#define __SIMPLE_DECODE_HH__
+
+#include <queue>
+
+#include "base/timebuf.hh"
+
+template<class Impl>
+class SimpleDecode
+{
+  private:
+    // Typedefs from the Impl.
+    typedef typename Impl::ISA ISA;
+    typedef typename Impl::FullCPU FullCPU;
+    typedef typename Impl::DynInstPtr DynInstPtr;
+    typedef typename Impl::Params Params;
+    typedef typename Impl::CPUPol CPUPol;
+
+    // Typedefs from the CPU policy.
+    typedef typename CPUPol::FetchStruct FetchStruct;
+    typedef typename CPUPol::DecodeStruct DecodeStruct;
+    typedef typename CPUPol::TimeStruct TimeStruct;
+
+    // Typedefs from the ISA.
+    typedef typename ISA::Addr Addr;
+
+  public:
+    // The only time decode will become blocked is if dispatch becomes
+    // blocked, which means IQ or ROB is probably full.
+    enum Status {
+        Running,
+        Idle,
+        Squashing,
+        Blocked,
+        Unblocking
+    };
+
+  private:
+    // May eventually need statuses on a per thread basis.
+    Status _status;
+
+  public:
+    SimpleDecode(Params &params);
+
+    void regStats();
+
+    void setCPU(FullCPU *cpu_ptr);
+
+    void setTimeBuffer(TimeBuffer<TimeStruct> *tb_ptr);
+
+    void setDecodeQueue(TimeBuffer<DecodeStruct> *dq_ptr);
+
+    void setFetchQueue(TimeBuffer<FetchStruct> *fq_ptr);
+
+    void tick();
+
+    void decode();
+
+    // Might want to make squash a friend function.
+    void squash();
+
+  private:
+    void block();
+
+    inline void unblock();
+
+    void squash(DynInstPtr &inst);
+
+    // Interfaces to objects outside of decode.
+    /** CPU interface. */
+    FullCPU *cpu;
+
+    /** Time buffer interface. */
+    TimeBuffer<TimeStruct> *timeBuffer;
+
+    /** Wire to get rename's output from backwards time buffer. */
+    typename TimeBuffer<TimeStruct>::wire fromRename;
+
+    /** Wire to get iew's information from backwards time buffer. */
+    typename TimeBuffer<TimeStruct>::wire fromIEW;
+
+    /** Wire to get commit's information from backwards time buffer. */
+    typename TimeBuffer<TimeStruct>::wire fromCommit;
+
+    /** Wire to write information heading to previous stages. */
+    // Might not be the best name as not only fetch will read it.
+    typename TimeBuffer<TimeStruct>::wire toFetch;
+
+    /** Decode instruction queue. */
+    TimeBuffer<DecodeStruct> *decodeQueue;
+
+    /** Wire used to write any information heading to rename. */
+    typename TimeBuffer<DecodeStruct>::wire toRename;
+
+    /** Fetch instruction queue interface. */
+    TimeBuffer<FetchStruct> *fetchQueue;
+
+    /** Wire to get fetch's output from fetch queue. */
+    typename TimeBuffer<FetchStruct>::wire fromFetch;
+
+    /** Skid buffer between fetch and decode. */
+    std::queue<FetchStruct> skidBuffer;
+
+  private:
+    //Consider making these unsigned to avoid any confusion.
+    /** Rename to decode delay, in ticks. */
+    unsigned renameToDecodeDelay;
+
+    /** IEW to decode delay, in ticks. */
+    unsigned iewToDecodeDelay;
+
+    /** Commit to decode delay, in ticks. */
+    unsigned commitToDecodeDelay;
+
+    /** Fetch to decode delay, in ticks. */
+    unsigned fetchToDecodeDelay;
+
+    /** The width of decode, in instructions. */
+    unsigned decodeWidth;
+
+    /** The instruction that decode is currently on.  It needs to have
+     *  persistent state so that when a stall occurs in the middle of a
+     *  group of instructions, it can restart at the proper instruction.
+     */
+    unsigned numInst;
+
+    Stats::Scalar<> decodeIdleCycles;
+    Stats::Scalar<> decodeBlockedCycles;
+    Stats::Scalar<> decodeUnblockCycles;
+    Stats::Scalar<> decodeSquashCycles;
+    Stats::Scalar<> decodeBranchMispred;
+    Stats::Scalar<> decodeControlMispred;
+    Stats::Scalar<> decodeDecodedInsts;
+    Stats::Scalar<> decodeSquashedInsts;
+};
+
+#endif // __SIMPLE_DECODE_HH__