gem5/src/arch/sparc/regfile.hh

/*
 * Copyright (c) 2003-2005 The Regents of The University of Michigan
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are
 * met: redistributions of source code must retain the above copyright
 * notice, this list of conditions and the following disclaimer;
 * redistributions in binary form must reproduce the above copyright
 * notice, this list of conditions and the following disclaimer in the
 * documentation and/or other materials provided with the distribution;
 * neither the name of the copyright holders nor the names of its
 * contributors may be used to endorse or promote products derived from
 * this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
 * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
 * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 *
 * Authors: Gabe Black
 *          Ali Saidi
 */

#ifndef __ARCH_SPARC_REGFILE_HH__
#define __ARCH_SPARC_REGFILE_HH__

#include "arch/sparc/exceptions.hh"
#include "arch/sparc/faults.hh"
#include "base/trace.hh"
#include "sim/byteswap.hh"
#include "cpu/cpuevent.hh"
#include "sim/host.hh"

class Checkpoint;

namespace SparcISA
{

    typedef uint8_t  RegIndex;

    // MAXTL - maximum trap level
    const int MaxPTL = 2;
    const int MaxTL  = 6;
    const int MaxGL  = 3;
    const int MaxPGL = 2;

    // NWINDOWS - number of register windows, can be 3 to 32
    const int NWindows = 32;

    const int AsrStart = 0;
    const int PrStart = 32;
    const int HprStart = 64;
    const int MiscStart = 96;

    const uint64_t Bit64 = (1ULL << 63);
    class IntRegFile
    {
      protected:
        static const int FrameOffsetBits = 3;
        static const int FrameNumBits = 2;

        static const int RegsPerFrame = 1 << FrameOffsetBits;
        static const int FrameNumMask =
                (FrameNumBits == sizeof(int)) ?
                (unsigned int)(-1) :
                (1 << FrameNumBits) - 1;
        static const int FrameOffsetMask =
                (FrameOffsetBits == sizeof(int)) ?
                (unsigned int)(-1) :
                (1 << FrameOffsetBits) - 1;

        IntReg regGlobals[MaxGL][RegsPerFrame];
        IntReg regSegments[2 * NWindows][RegsPerFrame];

        enum regFrame {Globals, Outputs, Locals, Inputs, NumFrames};

        IntReg * regView[NumFrames];

        static const int RegGlobalOffset = 0;
        static const int FrameOffset = MaxGL * RegsPerFrame;
        int offset[NumFrames];

      public:

        int flattenIndex(int reg)
        {
            int flatIndex = offset[reg >> FrameOffsetBits]
                | (reg & FrameOffsetMask);
            DPRINTF(Sparc, "Flattened index %d into %d.\n", reg, flatIndex);
            return flatIndex;
        }

        void clear()
        {
            int x;
            for (x = 0; x < MaxGL; x++)
                memset(regGlobals[x], 0, sizeof(regGlobals[x]));
            for(int x = 0; x < 2 * NWindows; x++)
                bzero(regSegments[x], sizeof(regSegments[x]));
        }

        IntRegFile()
        {
            offset[Globals] = 0;
            regView[Globals] = regGlobals[0];
            setCWP(0);
            clear();
        }

        IntReg readReg(int intReg)
        {
            IntReg val =
                regView[intReg >> FrameOffsetBits][intReg & FrameOffsetMask];
            DPRINTF(Sparc, "Read register %d = 0x%x\n", intReg, val);
            return val;
        }

        Fault setReg(int intReg, const IntReg &val)
        {
            if(intReg)
                DPRINTF(Sparc, "Wrote register %d = 0x%x\n", intReg, val);
            regView[intReg >> FrameOffsetBits][intReg & FrameOffsetMask] = val;
            return NoFault;
        }

        //This doesn't effect the actual CWP register.
        //It's purpose is to adjust the view of the register file
        //to what it would be if CWP = cwp.
        void setCWP(int cwp)
        {
            int index = ((NWindows - cwp) % NWindows) * 2;
            offset[Outputs] = FrameOffset + (index * RegsPerFrame);
            offset[Locals] = FrameOffset + ((index+1) * RegsPerFrame);
            offset[Inputs] = FrameOffset +
                (((index+2) % (NWindows * 2)) * RegsPerFrame);
            regView[Outputs] = regSegments[index];
            regView[Locals] = regSegments[index+1];
            regView[Inputs] = regSegments[(index+2) % (NWindows * 2)];

            DPRINTF(Sparc, "Changed the CWP value to %d\n", cwp);
        }

        void setGlobals(int gl)
        {

            DPRINTF(Sparc, "Now using %d globals", gl);

            regView[Globals] = regGlobals[gl];
            offset[Globals] = RegGlobalOffset + gl * RegsPerFrame;
        }

        void serialize(std::ostream &os);

        void unserialize(Checkpoint *cp, const std::string &section);
    };

    typedef float float32_t;
    typedef double float64_t;
    //FIXME long double refers to a 10 byte float, rather than a
    //16 byte float as required. This data type may have to be emulated.
    typedef double float128_t;

    class FloatRegFile
    {
      public:
        static const int SingleWidth = 32;
        static const int DoubleWidth = 64;
        static const int QuadWidth = 128;

      protected:

        //Since the floating point registers overlap each other,
        //A generic storage space is used. The float to be returned is
        //pulled from the appropriate section of this region.
        char regSpace[(SingleWidth / 8) * NumFloatRegs];

      public:

        void clear()
        {
            bzero(regSpace, sizeof(regSpace));
        }

        FloatReg readReg(int floatReg, int width)
        {
            //In each of these cases, we have to copy the value into a temporary
            //variable. This is because we may otherwise try to access an
            //unaligned portion of memory.
            switch(width)
            {
              case SingleWidth:
                float32_t result32;
                memcpy(&result32, regSpace + 4 * floatReg, sizeof(result32));
                return htog(result32);
              case DoubleWidth:
                float64_t result64;
                memcpy(&result64, regSpace + 4 * floatReg, sizeof(result64));
                return htog(result64);
              case QuadWidth:
                float128_t result128;
                memcpy(&result128, regSpace + 4 * floatReg, sizeof(result128));
                return htog(result128);
              default:
                panic("Attempted to read a %d bit floating point register!", width);
            }
        }

        FloatRegBits readRegBits(int floatReg, int width)
        {
            //In each of these cases, we have to copy the value into a temporary
            //variable. This is because we may otherwise try to access an
            //unaligned portion of memory.
            switch(width)
            {
              case SingleWidth:
                uint32_t result32;
                memcpy(&result32, regSpace + 4 * floatReg, sizeof(result32));
                return htog(result32);
              case DoubleWidth:
                uint64_t result64;
                memcpy(&result64, regSpace + 4 * floatReg, sizeof(result64));
                return htog(result64);
              case QuadWidth:
                uint64_t result128;
                memcpy(&result128, regSpace + 4 * floatReg, sizeof(result128));
                return htog(result128);
              default:
                panic("Attempted to read a %d bit floating point register!", width);
            }
        }

        Fault setReg(int floatReg, const FloatReg &val, int width)
        {
            //In each of these cases, we have to copy the value into a temporary
            //variable. This is because we may otherwise try to access an
            //unaligned portion of memory.

            uint32_t result32;
            uint64_t result64;
            DPRINTF(Sparc, "Setting floating point register %d\n", floatReg);
            switch(width)
            {
              case SingleWidth:
                result32 = gtoh((uint32_t)val);
                memcpy(regSpace + 4 * floatReg, &result32, sizeof(result32));
                break;
              case DoubleWidth:
                result64 = gtoh((uint64_t)val);
                memcpy(regSpace + 4 * floatReg, &result64, sizeof(result64));
                break;
              case QuadWidth:
                panic("Quad width FP not implemented.");
                break;
              default:
                panic("Attempted to read a %d bit floating point register!", width);
            }
            return NoFault;
        }

        Fault setRegBits(int floatReg, const FloatRegBits &val, int width)
        {
            //In each of these cases, we have to copy the value into a temporary
            //variable. This is because we may otherwise try to access an
            //unaligned portion of memory.
            uint32_t result32;
            uint64_t result64;
            switch(width)
            {
              case SingleWidth:
                result32 = gtoh((uint32_t)val);
                memcpy(regSpace + 4 * floatReg, &result32, sizeof(result32));
                break;
              case DoubleWidth:
                result64 = gtoh((uint64_t)val);
                memcpy(regSpace + 4 * floatReg, &result64, sizeof(result64));
                break;
              case QuadWidth:
                panic("Quad width FP not implemented.");
                break;
              default:
                panic("Attempted to read a %d bit floating point register!", width);
            }
            return NoFault;
        }

        void serialize(std::ostream &os);

        void unserialize(Checkpoint *cp, const std::string &section);
    };

    enum MiscRegIndex
    {
        /** Ancillary State Registers */
        MISCREG_Y  = AsrStart + 0,
        MISCREG_CCR = AsrStart + 2,
        MISCREG_ASI = AsrStart + 3,
        MISCREG_TICK = AsrStart + 4,
        MISCREG_PC = AsrStart + 5,
        MISCREG_FPRS = AsrStart + 6,
        MISCREG_PCR = AsrStart + 16,
        MISCREG_PIC = AsrStart + 17,
        MISCREG_GSR = AsrStart + 19,
        MISCREG_SOFTINT_SET = AsrStart + 20,
        MISCREG_SOFTINT_CLR = AsrStart + 21,
        MISCREG_SOFTINT = AsrStart + 22,
        MISCREG_TICK_CMPR = AsrStart + 23,
        MISCREG_STICK = AsrStart + 24,
        MISCREG_STICK_CMPR = AsrStart + 25,

        /** Privilged Registers */
        MISCREG_TPC = PrStart + 0,
        MISCREG_TNPC = PrStart + 1,
        MISCREG_TSTATE = PrStart + 2,
        MISCREG_TT = PrStart + 3,
        MISCREG_PRIVTICK = PrStart + 4,
        MISCREG_TBA = PrStart + 5,
        MISCREG_PSTATE = PrStart + 6,
        MISCREG_TL = PrStart + 7,
        MISCREG_PIL = PrStart + 8,
        MISCREG_CWP = PrStart + 9,
        MISCREG_CANSAVE = PrStart + 10,
        MISCREG_CANRESTORE = PrStart + 11,
        MISCREG_CLEANWIN = PrStart + 12,
        MISCREG_OTHERWIN = PrStart + 13,
        MISCREG_WSTATE = PrStart + 14,
        MISCREG_GL = PrStart + 16,

        /** Hyper privileged registers */
        MISCREG_HPSTATE = HprStart + 0,
        MISCREG_HTSTATE = HprStart + 1,
        MISCREG_HINTP = HprStart + 3,
        MISCREG_HTBA = HprStart + 5,
        MISCREG_HVER = HprStart + 6,
        MISCREG_STRAND_STS_REG = HprStart + 16,
        MISCREG_HSTICK_CMPR = HprStart + 31,

        /** Floating Point Status Register */
        MISCREG_FSR = MiscStart + 0

    };

    // The control registers, broken out into fields
    class MiscRegFile
    {
      private:

        /* ASR Registers */
        union {
            uint64_t y;		// Y (used in obsolete multiplication)
            struct {
                uint64_t value:32;	// The actual value stored in y
                uint64_t :32;	// reserved bits
            } yFields;
        };
        union {
            uint8_t	ccr;		// Condition Code Register
            struct {
                union {
                    uint8_t icc:4;	// 32-bit condition codes
                    struct {
                        uint8_t c:1;	// Carry
                        uint8_t v:1;	// Overflow
                        uint8_t z:1;	// Zero
                        uint8_t n:1;	// Negative
                    } iccFields;
                };
                union {
                    uint8_t xcc:4;	// 64-bit condition codes
                    struct {
                        uint8_t c:1;	// Carry
                        uint8_t v:1;	// Overflow
                        uint8_t z:1;	// Zero
                        uint8_t n:1;	// Negative
                    } xccFields;
                };
            } ccrFields;
        };
        uint8_t asi;		// Address Space Identifier
        union {
            uint64_t tick;		// Hardware clock-tick counter
            struct {
                int64_t counter:63;	// Clock-tick count
                uint64_t npt:1;		// Non-priveleged trap
            } tickFields;
        };
        union {
            uint8_t		fprs;	// Floating-Point Register State
            struct {
                uint8_t dl:1;		// Dirty lower
                uint8_t du:1;		// Dirty upper
                uint8_t fef:1;		// FPRS enable floating-Point
            } fprsFields;
        };
        union {
            uint64_t softint;
            struct {
                uint64_t tm:1;
                uint64_t int_level:14;
                uint64_t sm:1;
            } softintFields;
        };
        union {
            uint64_t tick_cmpr;		// Hardware tick compare registers
            struct {
                uint64_t tick_cmpr:63;	// Clock-tick count
                uint64_t int_dis:1;		// Non-priveleged trap
            } tick_cmprFields;
        };
        union {
            uint64_t stick;		// Hardware clock-tick counter
            struct {
                int64_t :63;	// Not used, storage in SparcSystem
                uint64_t npt:1;		// Non-priveleged trap
            } stickFields;
        };
        union {
            uint64_t stick_cmpr;		// Hardware tick compare registers
            struct {
                uint64_t tick_cmpr:63;	// Clock-tick count
                uint64_t int_dis:1;		// Non-priveleged trap
            } stick_cmprFields;
        };


        /* Privileged Registers */
        uint64_t tpc[MaxTL];	// Trap Program Counter (value from
                                // previous trap level)
        uint64_t tnpc[MaxTL];	// Trap Next Program Counter (value from
                                // previous trap level)
        union {
            uint64_t tstate[MaxTL];	// Trap State
            struct {
                //Values are from previous trap level
                uint64_t cwp:5;		// Current Window Pointer
                uint64_t :3;	// Reserved bits
                uint64_t pstate:13;	// Process State
                uint64_t :3;	// Reserved bits
                uint64_t asi:8;		// Address Space Identifier
                uint64_t ccr:8;		// Condition Code Register
                uint64_t gl:8;		// Global level
            } tstateFields[MaxTL];
        };
        uint16_t tt[MaxTL];	// Trap Type (Type of trap which occured
                                // on the previous level)
        uint64_t tba;		// Trap Base Address

        union {
            uint16_t pstate;		// Process State Register
            struct {
                uint16_t :1;		// reserved
                uint16_t ie:1;		// Interrupt enable
                uint16_t priv:1;	// Privelege mode
                uint16_t am:1;		// Address mask
                uint16_t pef:1;		// PSTATE enable floating-point
                uint16_t :1;		// reserved2
                uint16_t mm:2;		// Memory Model
                uint16_t tle:1;		// Trap little-endian
                uint16_t cle:1;		// Current little-endian
            } pstateFields;
        };
        uint8_t tl;		// Trap Level
        uint8_t pil;		// Process Interrupt Register
        uint8_t cwp;		// Current Window Pointer
        uint8_t cansave;	// Savable windows
        uint8_t canrestore;	// Restorable windows
        uint8_t cleanwin;	// Clean windows
        uint8_t otherwin;	// Other windows
        union {
            uint8_t wstate;		// Window State
            struct {
                uint8_t normal:3;	// Bits TT<4:2> are set to on a normal
                                        // register window trap
                uint8_t other:3;	// Bits TT<4:2> are set to on an "otherwin"
                                        // register window trap
            } wstateFields;
        };
        uint8_t gl;             // Global level register


        /** Hyperprivileged Registers */
        union {
            uint64_t hpstate; // Hyperprivileged State Register
            struct {
                uint8_t tlz: 1;
                uint8_t :1;
                uint8_t hpriv:1;
                uint8_t :2;
                uint8_t red:1;
                uint8_t :4;
                uint8_t ibe:1;
                uint8_t id:1;
            } hpstateFields;
        };

        uint64_t htstate[MaxTL]; // Hyperprivileged Trap State Register
        uint64_t hintp;
        uint64_t htba; // Hyperprivileged Trap Base Address register
        union {
            uint64_t hstick_cmpr;		// Hardware tick compare registers
            struct {
                uint64_t tick_cmpr:63;	// Clock-tick count
                uint64_t int_dis:1;		// Non-priveleged trap
            } hstick_cmprFields;
        };

        uint64_t strandStatusReg; // Per strand status register


        /** Floating point misc registers. */
        union {
            uint64_t	fsr;	// Floating-Point State Register
            struct {
                union {
                    uint64_t cexc:5;	// Current excpetion
                    struct {
                        uint64_t nxc:1;		// Inexact
                        uint64_t dzc:1;		// Divide by zero
                        uint64_t ufc:1;		// Underflow
                        uint64_t ofc:1;		// Overflow
                        uint64_t nvc:1;		// Invalid operand
                    } cexcFields;
                };
                union {
                    uint64_t aexc:5;		// Accrued exception
                    struct {
                        uint64_t nxc:1;		// Inexact
                        uint64_t dzc:1;		// Divide by zero
                        uint64_t ufc:1;		// Underflow
                        uint64_t ofc:1;		// Overflow
                        uint64_t nvc:1;		// Invalid operand
                    } aexcFields;
                };
                uint64_t fcc0:2;		// Floating-Point condtion codes
                uint64_t :1;		// Reserved bits
                uint64_t qne:1;			// Deferred trap queue not empty
                                                // with no queue, it should read 0
                uint64_t ftt:3;			// Floating-Point trap type
                uint64_t ver:3;			// Version (of the FPU)
                uint64_t :2;		// Reserved bits
                uint64_t ns:1;			// Nonstandard floating point
                union {
                    uint64_t tem:5;			// Trap Enable Mask
                    struct {
                        uint64_t nxm:1;		// Inexact
                        uint64_t dzm:1;		// Divide by zero
                        uint64_t ufm:1;		// Underflow
                        uint64_t ofm:1;		// Overflow
                        uint64_t nvm:1;		// Invalid operand
                    } temFields;
                };
                uint64_t :2;		// Reserved bits
                uint64_t rd:2;			// Rounding direction
                uint64_t fcc1:2;		// Floating-Point condition codes
                uint64_t fcc2:2;		// Floating-Point condition codes
                uint64_t fcc3:2;		// Floating-Point condition codes
                uint64_t :26;		// Reserved bits
            } fsrFields;
        };

        // These need to check the int_dis field and if 0 then
        // set appropriate bit in softint and checkinterrutps on the cpu
#if FULL_SYSTEM
        /** Process a tick compare event and generate an interrupt on the cpu if
         * appropriate. */
        void processTickCompare(ThreadContext *tc);
        void processSTickCompare(ThreadContext *tc);
        void processHSTickCompare(ThreadContext *tc);

        typedef CpuEventWrapper<MiscRegFile,
                &MiscRegFile::processTickCompare> TickCompareEvent;
        TickCompareEvent *tickCompare;

        typedef CpuEventWrapper<MiscRegFile,
                &MiscRegFile::processSTickCompare> STickCompareEvent;
        STickCompareEvent *sTickCompare;

        typedef CpuEventWrapper<MiscRegFile,
                &MiscRegFile::processHSTickCompare> HSTickCompareEvent;
        HSTickCompareEvent *hSTickCompare;

        /** Fullsystem only register version of ReadRegWithEffect() */
        MiscReg readFSRegWithEffect(int miscReg, Fault &fault, ThreadContext *tc);
        /** Fullsystem only register version of SetRegWithEffect() */
        Fault setFSRegWithEffect(int miscReg, const MiscReg &val,
                ThreadContext * tc);
#endif
      public:

        void reset()
        {
            pstateFields.pef = 0; //No FPU
            //pstateFields.pef = 1; //FPU
#if FULL_SYSTEM
            //For SPARC, when a system is first started, there is a power
            //on reset Trap which sets the processor into the following state.
            //Bits that aren't set aren't defined on startup.
            tl = MaxTL;
            gl = MaxGL;

            tickFields.counter = 0; //The TICK register is unreadable bya
            tickFields.npt = 1; //The TICK register is unreadable by by !priv

            softint = 0; // Clear all the soft interrupt bits
            tick_cmprFields.int_dis = 1; // disable timer compare interrupts
            tick_cmprFields.tick_cmpr = 0; // Reset to 0 for pretty printing
            stickFields.npt = 1; //The TICK register is unreadable by by !priv
            stick_cmprFields.int_dis = 1; // disable timer compare interrupts
            stick_cmprFields.tick_cmpr = 0; // Reset to 0 for pretty printing


            tt[tl] = power_on_reset;
            pstate = 0; // fields 0 but pef
            pstateFields.pef = 1;

            hpstate = 0;
            hpstateFields.red = 1;
            hpstateFields.hpriv = 1;
            hpstateFields.tlz = 0; // this is a guess
            hintp = 0; // no interrupts pending
            hstick_cmprFields.int_dis = 1; // disable timer compare interrupts
            hstick_cmprFields.tick_cmpr = 0; // Reset to 0 for pretty printing
#else
/*	    //This sets up the initial state of the processor for usermode processes
            pstateFields.priv = 0; //Process runs in user mode
            pstateFields.ie = 1; //Interrupts are enabled
            fsrFields.rd = 0; //Round to nearest
            fsrFields.tem = 0; //Floating point traps not enabled
            fsrFields.ns = 0; //Non standard mode off
            fsrFields.qne = 0; //Floating point queue is empty
            fsrFields.aexc = 0; //No accrued exceptions
            fsrFields.cexc = 0; //No current exceptions

            //Register window management registers
            otherwin = 0; //No windows contain info from other programs
            canrestore = 0; //There are no windows to pop
            cansave = MaxTL - 2; //All windows are available to save into
            cleanwin = MaxTL;*/
#endif
        }

        MiscRegFile()
        {
            reset();
        }

        /** read a value out of an either an SE or FS IPR. No checking is done
         * about SE vs. FS as this is mostly used to copy the regfile. Thus more
         * register are copied that are necessary for FS. However this prevents
         * a bunch of ifdefs and is rarely called so is not performance
         * criticial. */
        MiscReg readReg(int miscReg);

        /** Read a value from an IPR. Only the SE iprs are here and the rest
         * are are readFSRegWithEffect (which is called by readRegWithEffect()).
         * Checking is done for permission based on state bits in the miscreg
         * file. */
        MiscReg readRegWithEffect(int miscReg, Fault &fault, ThreadContext *tc);

        /** write a value into an either an SE or FS IPR. No checking is done
         * about SE vs. FS as this is mostly used to copy the regfile. Thus more
         * register are copied that are necessary for FS. However this prevents
         * a bunch of ifdefs and is rarely called so is not performance
         * criticial.*/
        Fault setReg(int miscReg, const MiscReg &val);

        /** Write a value into an IPR. Only the SE iprs are here and the rest
         * are are setFSRegWithEffect (which is called by setRegWithEffect()).
         * Checking is done for permission based on state bits in the miscreg
         * file. */
        Fault setRegWithEffect(int miscReg,
                const MiscReg &val, ThreadContext * tc);

        void serialize(std::ostream & os);

        void unserialize(Checkpoint * cp, const std::string & section);

        void copyMiscRegs(ThreadContext * tc);

      protected:

        bool isHyperPriv() { return hpstateFields.hpriv; }
        bool isPriv() { return hpstateFields.hpriv || pstateFields.priv; }
        bool isNonPriv() { return !isPriv(); }
    };

    typedef union
    {
        IntReg  intreg;
        FloatReg   fpreg;
        MiscReg ctrlreg;
    } AnyReg;

    class RegFile
    {
      protected:
        Addr pc;		// Program Counter
        Addr npc;		// Next Program Counter
        Addr nnpc;

      public:
        Addr readPC()
        {
            return pc;
        }

        void setPC(Addr val)
        {
            pc = val;
        }

        Addr readNextPC()
        {
            return npc;
        }

        void setNextPC(Addr val)
        {
            npc = val;
        }

        Addr readNextNPC()
        {
            return nnpc;
        }

        void setNextNPC(Addr val)
        {
            nnpc = val;
        }

      protected:
        IntRegFile intRegFile;		// integer register file
        FloatRegFile floatRegFile;	// floating point register file
        MiscRegFile miscRegFile;	// control register file

      public:

        void clear()
        {
            intRegFile.clear();
            floatRegFile.clear();
        }

        int FlattenIntIndex(int reg)
        {
            return intRegFile.flattenIndex(reg);
        }

        MiscReg readMiscReg(int miscReg)
        {
            return miscRegFile.readReg(miscReg);
        }

        MiscReg readMiscRegWithEffect(int miscReg,
                Fault &fault, ThreadContext *tc)
        {
            return miscRegFile.readRegWithEffect(miscReg, fault, tc);
        }

        Fault setMiscReg(int miscReg, const MiscReg &val)
        {
            return miscRegFile.setReg(miscReg, val);
        }

        Fault setMiscRegWithEffect(int miscReg, const MiscReg &val,
                ThreadContext * tc)
        {
            return miscRegFile.setRegWithEffect(miscReg, val, tc);
        }

        FloatReg readFloatReg(int floatReg, int width)
        {
            return floatRegFile.readReg(floatReg, width);
        }

        FloatReg readFloatReg(int floatReg)
        {
            //Use the "natural" width of a single float
            return floatRegFile.readReg(floatReg, FloatRegFile::SingleWidth);
        }

        FloatRegBits readFloatRegBits(int floatReg, int width)
        {
            return floatRegFile.readRegBits(floatReg, width);
        }

        FloatRegBits readFloatRegBits(int floatReg)
        {
            //Use the "natural" width of a single float
            return floatRegFile.readRegBits(floatReg,
                    FloatRegFile::SingleWidth);
        }

        Fault setFloatReg(int floatReg, const FloatReg &val, int width)
        {
            return floatRegFile.setReg(floatReg, val, width);
        }

        Fault setFloatReg(int floatReg, const FloatReg &val)
        {
            //Use the "natural" width of a single float
            return setFloatReg(floatReg, val, FloatRegFile::SingleWidth);
        }

        Fault setFloatRegBits(int floatReg, const FloatRegBits &val, int width)
        {
            return floatRegFile.setRegBits(floatReg, val, width);
        }

        Fault setFloatRegBits(int floatReg, const FloatRegBits &val)
        {
            //Use the "natural" width of a single float
            return floatRegFile.setRegBits(floatReg, val,
                    FloatRegFile::SingleWidth);
        }

        IntReg readIntReg(int intReg)
        {
            return intRegFile.readReg(intReg);
        }

        Fault setIntReg(int intReg, const IntReg &val)
        {
            return intRegFile.setReg(intReg, val);
        }

        void serialize(std::ostream &os);
        void unserialize(Checkpoint *cp, const std::string &section);

      public:

        enum ContextParam
        {
            CONTEXT_CWP,
            CONTEXT_GLOBALS
        };
        typedef int ContextVal;

        void changeContext(ContextParam param, ContextVal val)
        {
            switch(param)
            {
              case CONTEXT_CWP:
                intRegFile.setCWP(val);
                break;
              case CONTEXT_GLOBALS:
                intRegFile.setGlobals(val);
                break;
              default:
                panic("Tried to set illegal context parameter in the SPARC regfile.\n");
            }
        }
    };

    void copyRegs(ThreadContext *src, ThreadContext *dest);

    void copyMiscRegs(ThreadContext *src, ThreadContext *dest);

    int InterruptLevel(uint64_t softint);

} // namespace SparcISA

#endif