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/*
 * ilog2 - return floor(log base 2 of x), where x > 0
 *   Example: ilog2(16) = 4
 *   Legal ops: ! ~ & ^ | + << >>
 *   Max ops: 90
 *   Rating: 4
 */
int ilog2(int x) {
  int bitsNumber=0;  
  bitsNumber=(!!(x>>16))<<4;  
  bitsNumber=bitsNumber+((!!(x>>(bitsNumber+8)))<<3);  
  bitsNumber=bitsNumber+((!!(x>>(bitsNumber+4)))<<2);  
  bitsNumber=bitsNumber+((!!(x>>(bitsNumber+2)))<<1);  
  bitsNumber=bitsNumber+(!!(x>>(bitsNumber+1))); 
  bitsNumber=bitsNumber+(!!bitsNumber)+(~0)+(!(1^x));  
  return bitsNumber;  
}