Gettysburg College

CS 221
Computer Organization and Assembly Language Programming

Fall 2024

Assignment 2

Due: Thu, Sep 12, by 11:59pm

Readings

Description

This assignment will focus on C++ and bitwise operations. There are two tasks:

Testing

Copy the following functions and use assertEquals for testing the code. This is similar to testing in JUnit. 

string to_string( const string& str )
{
	return str;
}

template<typename E1, typename E2>
void assertEquals( E1 a, E2 b )
{
	string strA = to_string( a );
	string strB = to_string( b );

	if ( strA != strB ) {
		cout << "failed: " << a << " != " << b << endl;
	}
}

Note that you will need to put at the very top: 

#include <iostream>
#include <string>
using namespace std;

Converter

Create C++ project called Converter with source file Converter.cpp and re-write all methods from Assignment 1 in C++.

Note the following:

Here are the C++ versions of the given Java code samples: 

char getSymbol(int digit)
{
    if (digit >= 0 && digit <= 9) {
        return (char)('0' + digit);
    }
    else {
        return (char)('A' + (digit - 10));
    }
}

int getValue(char symbol)
{
    if (symbol >= '0' && symbol <= '9') {
        return symbol - '0';
    }
    else {
        return (symbol - 'A') + 10;
    }
}

                               // no new, no =, just list key-value pairs
map<?, ?> theNameOfMap = { {key1, value1}, {key2, value2}, ... };

theNameOfMap[symbol] = value;   // CS111:  map[symbol] = value;

value = theNameOfMap[symbol];   // CS111:  value = map[symbol];

Bitset

Create C++ project called Bitset with source file Bitset.cpp.

Write class Bitset and test it in a main() function at the end of the file.

The class will have one data member of type unsigned short. This is 2 bytes and the bits are indexed from right-to-left (unlike strings or arrays): 

15            2 1 0
 x x x x .... x x x

Note: If you use variables for intermediate quantities, make them of type unsigned short.

Note: Avoid loops and arithmetic operators where possible.

Here is the list of required methods:

constructor()

Initializes the bitset to 0.
constructor(unsigned short theBits)

Initializes the bitset to the given bits.
void print()

The method is given for now. It will be modified later: 

// prints the value of the bitset as hex number    
// note: oct would print the octal version
//       dec would print the decimal version
//       there is no specifier for binary
void print()
{
    cout << hex << the-data-member << endl;

    cout << dec;   // should always be the last line in this method
}
bool none()

[no loops] Returns true if all bits are 0.
bool any()

[no loops] Returns true if at least one bit is set to 1.
bool all()

[no loops] Returns true if all bits have value 1. No multi-digit numbers.
void flip()

[no loops] Inverts the bits in the set (0s to 1s and 1s to 0s). Do not use ~.
bool get(int index)

[no loops] Returns the value of the bit at the given index.

Consider bitshift operation of a suitable mask.

void set()

[no loops] Sets all bits to 1. Do not use |.
void set(int index)

[no loops] Sets the bit at the given index to 1.
void clear()

[no loops] Sets all bits to 0. Do not use 0.
void clear(int index)

[no loops] Sets the bit at the given index to 0.
void swap()

[no loops] Swaps the values of the two halves (here the two bytes) of the data member.
void swapHi()

[no loops] Swaps the two halves in the high byte of the data member, i.e. the byte that corresponds to the higher powers of 2.
void swapLo()

[no loops] Swaps the two halves in the low byte of the data member, i.e. the byte that corresponds to the low powers of 2.
bool isPow2()

[no loops] Returns true if the value stored in the bitset is a power of 2.
void clearLast1()

[no loops] Sets to 0 only the last 1 in the bitset, i.e. the 1 bit that corresponds to the lowest power of 2. The rest of the bits are unchanged.
int count()

[loop needed] Returns the number of bits that are set to 1.

Use a loop with a mask that is shifted by one position on each cycle.

void printBinary()

[loop needed] Prints the binary representation of the data member 

// assuming the bitset has value 25, the output would be
  
bits.printBinary();          0b0000000000011001
void print()

Prints the bits in decimal, hexadecimal, octal, and binary in this format [implicit loop for binary]: 

// assuming the bitset has value 25, the output would be
  
bits.print();          [25, 0x19, 031, 0b0000000000011001]

What to turn in

Upload Converter.cpp and Bitset.cpp to the Moodle dropbox.