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kernel/util: Add bit hack utilities

This commit is contained in:
Pawel Dziepak 2013-10-02 21:24:46 +02:00
parent 26c3861891
commit 1f50d09018
2 changed files with 43 additions and 26 deletions
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42
headers/private/kernel/util/BitUtils.h Normal file
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@ -0,0 +1,42 @@
/*
* Copyright 2013 Haiku, Inc. All rights reserved.
* Distributed under the terms of the MIT License.
*
* Authors:
* Paweł Dziepak, pdziepak@quarnos.org
*/
#ifndef KERNEL_UTIL_BITUTIL_H
#define KERNEL_UTIL_BITUTIL_H
#include <SupportDefs.h>
// http://graphics.stanford.edu/~seander/bithacks.html
static inline uint32
nextPowerOf2(uint32 v)
{
v--;
v |= v >> 1;
v |= v >> 2;
v |= v >> 4;
v |= v >> 8;
v |= v >> 16;
v++;
return v;
}
// http://graphics.stanford.edu/~seander/bithacks.html
static inline uint32
countSetBits(uint32 v)
{
v = v - ((v >> 1) & 0x55555555);
v = (v & 0x33333333) + ((v >> 2) & 0x33333333);
return (((v + (v >> 4)) & 0xF0F0F0F) * 0x1010101) >> 24;
}
#endif // KERNEL_UTIL_RANDOM_H

27
src/system/kernel/arch/x86/arch_cpu.cpp
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@ -21,6 +21,7 @@
#include <debug.h>
#include <elf.h>
#include <smp.h>
#include <util/BitUtils.h>
#include <vm/vm.h>
#include <vm/vm_types.h>
#include <vm/VMAddressSpace.h>
@ -129,32 +130,6 @@ static uint32 sHierarchyMask[CPU_TOPOLOGY_LEVELS];
static uint32 sHierarchyShift[CPU_TOPOLOGY_LEVELS];
// http://graphics.stanford.edu/~seander/bithacks.html
static inline uint32
nextPowerOf2(uint32 v)
{
v--;
v |= v >> 1;
v |= v >> 2;
v |= v >> 4;
v |= v >> 8;
v |= v >> 16;
v++;
return v;
}
// http://graphics.stanford.edu/~seander/bithacks.html
static inline uint32
countSetBits(uint32 v)
{
v = v - ((v >> 1) & 0x55555555);
v = (v & 0x33333333) + ((v >> 2) & 0x33333333);
return (((v + (v >> 4)) & 0xF0F0F0F) * 0x1010101) >> 24;
}
static status_t
acpi_shutdown(bool rebootSystem)
{