/****************************************************************************
 ***   FILE: bits.cpp
 ***   DATE: Nov 15, 2003
 *** AUTHOR: Daniel Dementiev
 ***  DESCR: This is a short example for Algorithms class. This program
 ***         illustrates two ways of getting a bit representation of a number.
 ***         The first is "traditional" - by dividing number by two
 ***         and the other one by using the UNION construct and specifying
 ***         the size of structure elements in bits;
 ****************************************************************************/

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

typedef unsigned char byte;
typedef unsigned short int shword;


// ----------------------
// This special structure allows us to access aither a whole
// byte value (byte_value) or each bit inside that byte.
// The nested structure "bits" contains 8 elements (b0-b7)
// size of exactly one bit each.
// The "union" construction stores both the byte value "byte"
// and structure "bits" in the same memory cell.
// Thus, a value of a variable of the ByteBitMap type can be
// accessed as either:
//  - var.byte_value
//  or as
//  - var.bits
// ----------------------
union ByteBitMap {
   byte byte_value;
   struct {
      shword b0:1;
      shword b1:1;
      shword b2:1;
      shword b3:1;
      shword b4:1;
      shword b5:1;
      shword b6:1;
      shword b7:1;
   } bits;
};


void print_bits(byte value)
{
   ByteBitMap b;
   b.byte_value = value;
   cout<<static_cast<int>(b.byte_value)<<" = ";
   cout<<b.bits.b7<<b.bits.b6<<b.bits.b5<<b.bits.b4
       <<b.bits.b3<<b.bits.b2<<b.bits.b1<<b.bits.b0<<endl;
}

string bitwise(byte b)
{
   string res = "";
   for(int i=0;i<8;i++){
      res = (b%2?"1":"0") + res;
      b >>= 1;
   }
   return res;
}


// ----------------------------------
union IntByteMap {
	unsigned int int_value;
	struct {
		byte b0;
		byte b1;
		byte b2;
		byte b3;
	} bytes;
};


void print_bytes(unsigned int n)
{
	IntByteMap m;
	m.int_value = n;

	cout<<n<<" = "
	    <<static_cast<int>(m.bytes.b3)<<"."
	    <<static_cast<int>(m.bytes.b2)<<"."
	    <<static_cast<int>(m.bytes.b1)<<"."
	    <<static_cast<int>(m.bytes.b0)<<endl;
}



// ----------------------------------

void main()
{
   byte b;
   unsigned int  n;

	cout<<"Size of the ByteBitMap structure is "<<sizeof(ByteBitMap)<<endl;

   cout<<"Enter a small number (0 - 255): ";
   cin>>n;
   b = n;
   cout<<static_cast<int>(b)<<" = "<<bitwise(b)<<endl;
   print_bits(b);

   cout<<"Enter any integer number: ";
   cin>>n;
   print_bytes(n);
}