OMAPDSS: VENC: fix NULL pointer dereference in DSS2 VENC sysfs debug attr on OMAP4
[zen-stable.git] / include / linux / reciprocal_div.h
blobf9c90b33285b24b2ef9870ee3d3fe3cf78f9283d
1 #ifndef _LINUX_RECIPROCAL_DIV_H
2 #define _LINUX_RECIPROCAL_DIV_H
4 #include <linux/types.h>
6 /*
7 * This file describes reciprocical division.
9 * This optimizes the (A/B) problem, when A and B are two u32
10 * and B is a known value (but not known at compile time)
12 * The math principle used is :
13 * Let RECIPROCAL_VALUE(B) be (((1LL << 32) + (B - 1))/ B)
14 * Then A / B = (u32)(((u64)(A) * (R)) >> 32)
16 * This replaces a divide by a multiply (and a shift), and
17 * is generally less expensive in CPU cycles.
21 * Computes the reciprocal value (R) for the value B of the divisor.
22 * Should not be called before each reciprocal_divide(),
23 * or else the performance is slower than a normal divide.
25 extern u32 reciprocal_value(u32 B);
28 static inline u32 reciprocal_divide(u32 A, u32 R)
30 return (u32)(((u64)A * R) >> 32);
32 #endif