index
:
litmus-rt.git
archive/unc-master-3.0
archived-2013.1
archived-private-master
archived-semi-part
demo
ecrts-pgm-final
ecrts14-pgm-final
gpusync-rtss12
gpusync/staging
linux-tip
litmus2008-patch-series
master
pgm
prop/litmus-signals
prop/robust-tie-break
staging
test
tracing-devel
v2.6.34-with-arm-patches
v2015.1
wip-2011.2-bbb
wip-2011.2-bbb-trace
wip-2012.3-gpu
wip-2012.3-gpu-preport
wip-2012.3-gpu-rtss13
wip-2012.3-gpu-sobliv-budget-w-kshark
wip-aedzl-final
wip-aedzl-revised
wip-arbit-deadline
wip-aux-tasks
wip-bbb
wip-bbb-prio-don
wip-better-break
wip-binary-heap
wip-budget
wip-color
wip-color-jlh
wip-d10-hz1000
wip-default-clustering
wip-dissipation-jerickso
wip-dissipation2-jerickso
wip-ecrts14-pgm
wip-edf-hsb
wip-edf-os
wip-edf-tie-break
wip-edzl-critique
wip-edzl-final
wip-edzl-revised
wip-events
wip-extra-debug
wip-fix-switch-jerickso
wip-fix3
wip-fmlp-dequeue
wip-ft-irq-flag
wip-gpu-cleanup
wip-gpu-interrupts
wip-gpu-rtas12
wip-gpu-rtss12
wip-gpu-rtss12-srp
wip-gpusync-merge
wip-ikglp
wip-k-fmlp
wip-kernel-coloring
wip-kernthreads
wip-klmirqd-to-aux
wip-kshark
wip-litmus-3.2
wip-litmus2011.2
wip-litmus3.0-2011.2
wip-master-2.6.33-rt#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