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The implementation of int_sqrt() assumes that longs have 32 bits. On systems that have 64 bit longs this will result in gross errors when the argument to the function is greater than 2^32 - 1 on such systems. I doubt whether any such use is currently made of int_sqrt() but the attached patch fixes the problem anyway. Signed-off-by: Peter Williams <pwil3058@bigpond.com.au> Cc: Dave Jones <davej@codemonkey.org.uk> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
32 lines
533 B
C
32 lines
533 B
C
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#include <linux/kernel.h>
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#include <linux/module.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 op, res, one;
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op = x;
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res = 0;
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one = 1UL << (BITS_PER_LONG - 2);
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while (one > op)
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one >>= 2;
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while (one != 0) {
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if (op >= res + one) {
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op = op - (res + one);
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res = res + 2 * one;
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}
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res /= 2;
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one /= 4;
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}
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return res;
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}
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EXPORT_SYMBOL(int_sqrt);
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