/* * 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);