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v0.5.1
https://github.com/torvalds/linux
02 December 2023, 22:23:51 UTC
Revision bfe01a5ba2490f299e1d2d5508cbbbadd897bbe9 authored by Linus Torvalds on 05 October 2014, 19:23:04 UTC, committed by Linus Torvalds on 05 October 2014, 19:23:04 UTC 
Linux 3.17
1 parent ef0a599
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Tip revision: bfe01a5ba2490f299e1d2d5508cbbbadd897bbe9 authored by Linus Torvalds on 05 October 2014, 19:23:04 UTC
Linux 3.17
Tip revision: bfe01a5
int_sqrt.c 
/*
 * 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);
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