Please refer to this link for the main instructions: http://www.co-pylit.org/cou

Question

Please refer to this link for the main instructions: http://www.co-pylit.org/courses/cosc2325/Assignments/Lab2/index.html#lab2 ( all i got from it is we are supposed to complete the class and test it?) here's ALU.cpp #include "ALU.h" #include ALU::ALU(void) { } bool ALU::get_carry( void ) { return carry; } bool ALU::get_overflow( void ) { return overflow; } int16_t ALU::get_result( void ) { return result; } void ALU::add(uint16_t op1, uint16_t op2, int size) { } void ALU::sub(uint16_t op1, uint16_t op2, int size) { } ____________________________________________________________________ here's ALU.h: #pragma once #include class ALU { public: // constructor ALU( void ); int16_t get_result( void ); bool get_carry( void ); bool get_overflow( void ); void add(uint16_t op1, uint16_t op2, int size); void sub(uint16_t op1, uint16_t op2, int size); private: uint16_t result; bool carry; bool overflow; }; _________________________________________ for additional clarification about the files, see this git repo; https://github.com/rblack42/CPUsim Your help would be greatly appreciated.

Explanation / Answer

Carry is related to unsigned data types.

And overflow is related to signed data types.

for that you need two add & two sub functions. Modify the implementation as per that. Function overloading can help.

        void add(uint16_t op1, uint16_t op2, int size);
        void sub(uint16_t op1, uint16_t op2, int size);

        void add(int16_t op1, int16_t op2, int size);
        void sub(int16_t op1, int16_t op2, int size);

And modify the carry and overflow condition as per the rules in

http://www.co-pylit.org/courses/cosc2325/Assignments/Lab2/carry-rules.html#carry-rules

Please save these two files and compile. And make your own test cases to test

/********************************/

/*
* ALU.h
*
* Created on: 05-Oct-2017
*      Author:
*/

#ifndef ALU_H_
#define ALU_H_
#pragma once
//#include <cstdint> //you can uncomment this line if your compiler supports.
typedef short int16_t; // you can comment this line if your toolchain supports int16_t
typedef unsigned short uint16_t; // you can comment this line if your toolchain supports uint16_t

class ALU {
    public:
        // constructor
        ALU( void );

        int16_t get_result( void );
        bool get_carry( void );
        bool get_overflow( void );

        void add(uint16_t op1, uint16_t op2, int size);
        void sub(uint16_t op1, uint16_t op2, int size);

    private:
        int16_t result;
        bool carry;
        bool overflow;
};

#endif /* ALU_H_ */

/********************************/

/*
* ALU.cpp
*
* Created on: 05-Oct-2017
*      Author:
*/
#include <iostream>
#include "ALU.h"
//#include

using namespace std;
int main()
{
   ALU alu;
   alu.add(100,170,1);
   cout<<"carry present: "<<alu.get_carry()<<"Result: "<<alu.get_result()<<endl;
   alu.sub(100,170,1);
   cout<<"overflow present: "<<alu.get_overflow()<<"Result: "<<alu.get_result()<<endl;
   return 0;
}
ALU::ALU(void)
{
    result = 0;
    carry = false;
    overflow = false;
}
bool ALU::get_carry( void )
{
   return carry;
}
bool ALU::get_overflow( void )
{
   return overflow;
}
int16_t ALU::get_result( void )
{
   return result;
}
void ALU::add(uint16_t op1, uint16_t op2, int size)
{
   int tmp;
   if(size==1)
   {
       tmp=op1+op2;
       if(tmp>0xff)
       {
           carry=true;
       }
       else
       {
           carry=false;
       }
       result=(unsigned char)tmp; // this will truncate the result after 255
   }
   else if(size==2)
   {
       tmp=op1+op2;
       if(tmp>0xffff)
       {
           carry=true;
       }
       else
       {
           carry=false;
       }
       result=(unsigned short)tmp; // this will truncate the result after 65535
   }

}
void ALU::sub(uint16_t op1, uint16_t op2, int size)
{
   unsigned int tmp;
   if(size==1)
   {
       tmp=op1-op2;
       if(tmp>0x7f)
       {
           overflow=true;
       }
       else
       {
           overflow=false;
       }
       result=(char)tmp;
   }
   else if(size==2)
   {
       tmp=op1-op2;
       if(tmp>0x7fff)
       {
           overflow=true;
       }
       else
       {
           overflow=false;
       }
       result=(int16_t)tmp;
   }
}

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