#include <stdio.h>
#include <limits.h>

typedef unsigned char byte;

void show_bytes(void * start, size_t len){

  printf("%lu bytes from %p:", len, start);

  int i;
  for(i = 0; i < len; i++){
    printf(" %.2x", ((byte *) start)[i]);
  }
  printf("\n");

}


void shift_demo(){

  unsigned char temp = (unsigned char) (0x41 << 4); // cast truncates to one byte
  printf("0x41 << 4 = %.2x\n", temp);
  temp = 0x41 >> 4;
  printf("0x41 >> 4 = %.2x\n", temp);

  int temp2 =41 << 4;
  printf("41 << 4 = %d\n", temp2);
  temp2 = 41 >> 4;
  printf("41 >> 4 = %d\n", temp2);
  temp2 = -41 << 4;
  printf("-41 << 4 = %d\n", temp2);
  temp2 = -41 >> 4;
  printf("-41 >> 4 = %d\n", temp2);

}

void fun_demo(){ // Note: skipped this in Spring 2020

  int x = 7;
  int y = x & 1;
  printf("%d & 1 = %d\n",x,y);

  x = -14;
  y = (x + 7) & 0xFFFFFFF8;
  printf("(%d + 7) & OxFFFFFFF8 = %d\n",x,y);

  void * p = &x;
  void * p2 = (void *) ((long)p & ~((long)0x3FF));
  void * p3 = (void *) (((long)p >> 10) << 10);
  printf("%p & ~0x3FF = %p\n",p,p2);
  printf("((%p >> 10) << 10) = %p\n",p,p3);

  void * p4 = (void *) ((long)p & ((long)0x3FF));
  printf("%p & 0x3FF = %p\n",p,p4);
}

int main()
{
  
  printf("\nShift demo:\n");
  shift_demo();
  
  //printf("\nFun demo:\n");
  //int_demo();

  return 0;
}