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#ifndef _LINUX_RECIPROCAL_DIV_H

#define _LINUX_RECIPROCAL_DIV_H

#include <linux/types.h>

/*

 * This file describes reciprocical division.

 *

 * This optimizes the (A/B) problem, when A and B are two u32

 * and B is a known value (but not known at compile time)

 *

 * The math principle used is :

 *   Let RECIPROCAL_VALUE(B) be (((1LL << 32) + (B - 1))/ B)

 *   Then A / B = (u32)(((u64)(A) * (R)) >> 32)

 *

 * This replaces a divide by a multiply (and a shift), and

 * is generally less expensive in CPU cycles.

 */

/*

 * Computes the reciprocal value (R) for the value B of the divisor.

 * Should not be called before each reciprocal_divide(),

 * or else the performance is slower than a normal divide.

 */

extern u32 reciprocal_value(u32 B);

static inline u32 reciprocal_divide(u32 A, u32 R)

{

        return (u32)(((u64)A * R) >> 32);

}

#endif