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