// SPDX-License-Identifier: GPL-2.0
  /*
   * Copyright (C) 2013 Davidlohr Bueso <davidlohr.bueso@hp.com>
   *
   *  Based on the shift-and-subtract algorithm for computing integer
   *  square root from Guy L. Steele.
   */
  
  #include <linux/kernel.h>
  #include <linux/export.h>
  
  /**
   * int_sqrt - rough approximation to sqrt
   * @x: integer of which to calculate the sqrt
   *
   * A very rough approximation to the sqrt() function.
   */
  unsigned long int_sqrt(unsigned long x)
  {
  	unsigned long b, m, y = 0;
  
  	if (x <= 1)
  		return x;
  
  	m = 1UL << (BITS_PER_LONG - 2);
  	while (m != 0) {
  		b = y + m;
  		y >>= 1;
  
  		if (x >= b) {
  			x -= b;
  			y += m;
  		}
  		m >>= 2;
  	}
  
  	return y;
  }
  EXPORT_SYMBOL(int_sqrt);