//
// prototypes.h
//
// Description:
//  AD-MIPS Function Prototypes
//
// Version:
//      $Id$
//
// Revision:
// 	$Log$
//
// Author:
//  Brian J. Alliet
//  Jonathon W. Donaldson
//

#ifndef _PROTOTYPES_H
#define _PROTOTYPES_H

/*
 * Adder (just adds instead of having to use entire BusALU object)
 */
class Adder : public Connector {

    public:
        Adder(const char *id, int numbits);

        void connectFrom(OutFlow& op1, OutFlow &op2);

        ~Adder();

        OutFlow& OUT() { return m_output; }

        virtual long computeValue();

    private:
        OutFlow m_output;
        OutFlow *m_op1;
        OutFlow *m_op2;

};

/*
 * Injector (see Injector.C)
 */
class Injector : public Connector {

    public:
        Injector(const char *id, int numbits);

        ~Injector();

        OutFlow& OUT() { return m_output; }

        virtual long computeValue();

    private:
        OutFlow m_output;
    public:
        long m_val;

};


/*
 * Bus for sign-extension and shifting
 */
class SuperBus : public Bus {

    public:
        SuperBus(const char *id, int numbits, long mask=~0, int shift=0);
        ~SuperBus();

        virtual long computeValue();

    private:
        long m_mask;
        int m_shift;

};


/*
 * Creates logical hardware connections for the AD-MIPS CPU
 */
void make_connections();

/*
 * Performs all forwarding for AD-MIPS pipeline
 */
extern StorageObject* forward(long reg_num, StorageObject* fallback, int from);

/*
 * Pipeline stage functions.
 */
extern void fetch();
extern void decode(); extern bool branch();
extern void execute();
extern void memory();
extern void writeback();

extern long mips_syscall(long nr, long a0, long a1, long a2);

static inline long OP(StorageObject& ir)    { return ir(31,26); }
static inline long RS(StorageObject& ir)    { return ir(25,21); }
static inline long RT(StorageObject& ir)    { return ir(20,16); }
static inline long RD(StorageObject& ir)    { return ir(15,11); }
static inline long SHAMT(StorageObject& ir) { return ir(10,6);  }
static inline long FUNC(StorageObject& ir)  { return ir(5,0);   }

// test if instruction loads memory
static inline bool loadsMem(StorageObject& ir) {
    return ir(29,29) == 0 && ir(31,31) == 1;
}

// test if instrux writes to memory
static inline bool storesMem(StorageObject& ir) {
    return ir(29,29) == 1 && ir(31,31) == 1;
}

static inline bool writesRD(StorageObject& ir) {
    return OP(ir) == 0x0 && FUNC(ir) != 0x8 /* JAL */ && FUNC(ir) != 0x9 /* JALR */ && FUNC(ir) != 0xc /* SYSCALL */;
}

static inline bool writesRT(StorageObject& ir) {
    return (ir(29,29) == 1 && ir(31,31) == 0) || loadsMem(ir);
}

static inline bool writesRA(StorageObject& ir) {
    return OP(ir) == 0x03 /* JAL */ 
       || (OP(ir) == 0x00 && FUNC(ir) == 0x09 /* JALR */)
       || (OP(ir) == 0x01 && ir(20,20) == 1 /* B*AL */)
       ;
}

static inline bool writesV0(StorageObject &ir) {
    return OP(ir) == 0x0 && FUNC(ir) == 0xc /* SYSCALL */;
}

#endif