/*! \file cbits.c
    
  Illustrating concepts discussed in 03-Cbits.txt notes.

  To compile use the following command:
    gcc -Wall -g cbits.c
  
  To run type:
    ./a.out

*/
#include <stdio.h>

int main() {

    // Checking the 2's complement representation for 30 and -75.
    printf("==== Hex representation for 2's complement of 30 and -75\n");
    int x = 30;
    printf("x = 0x%X\n", x);
    x = -75;
    printf("x = 0x%X\n", x);
    
    // shift right logical
    printf("\n==== shift right logical\n");
    unsigned short y = 0xFFFF;
    printf("y = 0x%hX = %hu\n", y, y); 
    printf("y >> 2  = 0x%hX = %hu\n", y >> 2, y >> 2);

    // shift right arithmetic
    printf("\n==== shift right arithmetic\n");
    short z = -4;
    printf("z = 0x%hX = %hd\n", z, z); 
    printf("z >> 2  = 0x%hX = %hd\n", z >> 2, z >> 2);

    // shift left logical
    printf("\n==== shift left logical\n");
    printf("z = 0x%hX = %hd\n", z, z); 
    printf("z << 2  = 0x%hX = %hd\n", z << 2, z << 2);

    // masking
    printf("\n==== masking\n");
    unsigned int num =  0x55555555;
    unsigned int mask = 0x80000000;
    int MSB = mask & num;
    printf("MSB = %d\n", MSB);
    mask = mask >> 1;
    printf("next bit = %d (0x%X)\n", mask & num, mask & num);

    // Big-Endian or Little-Endian?
    printf("\n==== big-endian or little-endian\n");
    unsigned int a = 0x41424344;
    char *ptrChar = (char *) &a;

    int i;
    for ( i = 0; i < sizeof( unsigned int ); ++i ) {
        printf( "%c ", ptrChar[i] );
    }
    printf("\n");

    return 0;
}