// 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/export.h>#include <linux/bitops.h>#include <linux/limits.h>#include <linux/math.h>/** * int_sqrt - computes the integer square root * @x: integer of which to calculate the sqrt * * Computes: floor(sqrt(x)) */unsigned long int_sqrt(unsigned long x){ unsigned long b, m, y = 0; if (x <= 1) return x; m = 1UL << (__fls(x) & ~1UL); while (m != 0) { b = y + m; y >>= 1; if (x >= b) { x -= b; y += m; } m >>= 2; } return y;}EXPORT_SYMBOL(int_sqrt);#if BITS_PER_LONG < 64/** * int_sqrt64 - strongly typed int_sqrt function when minimum 64 bit input * is expected. * @x: 64bit integer of which to calculate the sqrt */u32 int_sqrt64(u64 x){ u64 b, m, y = 0; if (x <= ULONG_MAX) return int_sqrt((unsigned long) x); m = 1ULL << ((fls64(x) - 1) & ~1ULL); while (m != 0) { b = y + m; y >>= 1; if (x >= b) { x -= b; y += m; } m >>= 2; } return y;}EXPORT_SYMBOL(int_sqrt64);#endif
// 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/export.h>
#include <linux/bitops.h>
#include <linux/limits.h>
#include <linux/math.h>
/**
* int_sqrt - computes the integer square root
* @x: integer of which to calculate the sqrt
*
* Computes: floor(sqrt(x))
*/
unsigned long int_sqrt(unsigned long x)
{
unsigned long b, m, y = 0;
if (x <= 1)
return x;
m = 1UL << (__fls(x) & ~1UL);
while (m != 0) {
b = y + m;
y >>= 1;
if (x >= b) {
x -= b;
y += m;
}
m >>= 2;
}
return y;
}
EXPORT_SYMBOL(int_sqrt);
#if BITS_PER_LONG < 64
/**
* int_sqrt64 - strongly typed int_sqrt function when minimum 64 bit input
* is expected.
* @x: 64bit integer of which to calculate the sqrt
*/
u32 int_sqrt64(u64 x)
{
u64 b, m, y = 0;
if (x <= ULONG_MAX)
return int_sqrt((unsigned long) x);
m = 1ULL << ((fls64(x) - 1) & ~1ULL);
while (m != 0) {
b = y + m;
y >>= 1;
if (x >= b) {
x -= b;
y += m;
}
m >>= 2;
}
return y;
}
EXPORT_SYMBOL(int_sqrt64);
#endif