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// Copyright 2009-2020 Intel Corporation
// SPDX-License-Identifier: Apache-2.0
#pragma once
#include "intrinsics.h"
#include "sysinfo.h"
#include "atomic.h"
namespace embree
{
/*! system barrier using operating system */
class BarrierSys
{
public:
/*! construction / destruction */
BarrierSys (size_t N = 0);
~BarrierSys ();
private:
/*! class in non-copyable */
BarrierSys (const BarrierSys& other) DELETED; // do not implement
BarrierSys& operator= (const BarrierSys& other) DELETED; // do not implement
public:
/*! intializes the barrier with some number of threads */
void init(size_t count);
/*! lets calling thread wait in barrier */
void wait();
private:
void* opaque;
};
/*! fast active barrier using atomitc counter */
struct BarrierActive
{
public:
BarrierActive ()
: cntr(0) {}
void reset() {
cntr.store(0);
}
void wait (size_t numThreads)
{
cntr++;
while (cntr.load() != numThreads)
pause_cpu();
}
private:
std::atomic<size_t> cntr;
};
/*! fast active barrier that does not require initialization to some number of threads */
struct BarrierActiveAutoReset
{
public:
BarrierActiveAutoReset ()
: cntr0(0), cntr1(0) {}
void wait (size_t threadCount)
{
cntr0.fetch_add(1);
while (cntr0 != threadCount) pause_cpu();
cntr1.fetch_add(1);
while (cntr1 != threadCount) pause_cpu();
cntr0.fetch_add(-1);
while (cntr0 != 0) pause_cpu();
cntr1.fetch_add(-1);
while (cntr1 != 0) pause_cpu();
}
private:
std::atomic<size_t> cntr0;
std::atomic<size_t> cntr1;
};
class LinearBarrierActive
{
public:
/*! construction and destruction */
LinearBarrierActive (size_t threadCount = 0);
~LinearBarrierActive();
private:
/*! class in non-copyable */
LinearBarrierActive (const LinearBarrierActive& other) DELETED; // do not implement
LinearBarrierActive& operator= (const LinearBarrierActive& other) DELETED; // do not implement
public:
/*! intializes the barrier with some number of threads */
void init(size_t threadCount);
/*! thread with threadIndex waits in the barrier */
void wait (const size_t threadIndex);
private:
volatile unsigned char* count0;
volatile unsigned char* count1;
volatile unsigned int mode;
volatile unsigned int flag0;
volatile unsigned int flag1;
volatile size_t threadCount;
};
}
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