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/*
SuperCollider real time audio synthesis system
Copyright (c) 2002 James McCartney. All rights reserved.
http://www.audiosynth.com
Copyright (c) 2013 Tim Blechmann
This program is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 2 of the License, or
(at your option) any later version.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program; if not, write to the Free Software
Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
*/
#pragma once
#include <atomic>
/////////////////////////////////////////////////////////////////////
namespace SCMsgFifo {
using std::memory_order_relaxed;
using std::memory_order_release;
template <class MsgType, int N> class MsgFifo {
public:
MsgFifo(): mReadHead(0), mWriteHead(0), mFreeHead(0) {}
void MakeEmpty() {
int writeHead = mWriteHead.load();
mReadHead.store(writeHead, memory_order_relaxed);
mFreeHead.store(writeHead, memory_order_release);
}
bool IsEmpty() { return mReadHead.load(memory_order_relaxed) == mWriteHead.load(memory_order_relaxed); }
bool HasData() { return mReadHead.load(memory_order_relaxed) != mWriteHead.load(memory_order_relaxed); }
bool NeedsFree() { return mFreeHead.load(memory_order_relaxed) != mReadHead.load(memory_order_relaxed); }
bool Write(MsgType& data) {
unsigned int next = NextPos(mWriteHead.load(memory_order_relaxed));
if (next == mFreeHead.load(memory_order_relaxed))
return false; // fifo is full
mItems[next] = data;
mWriteHead.store(next, memory_order_release);
return true;
}
void Perform() // get next and advance
{
while (HasData()) {
unsigned int next = NextPos(mReadHead.load(memory_order_relaxed));
mItems[next].Perform();
mReadHead.store(next, memory_order_release);
}
}
void Free() // reclaim messages
{
while (NeedsFree()) {
unsigned int next = NextPos(mFreeHead.load(memory_order_relaxed));
mItems[next].Free();
mFreeHead.store(next, memory_order_release);
}
}
private:
int NextPos(int inPos) { return (inPos + 1) & (N - 1); }
std::atomic<int> mReadHead, mWriteHead, mFreeHead;
MsgType mItems[N];
};
/////////////////////////////////////////////////////////////////////
template <class MsgType, int N> class MsgFifoNoFree {
public:
MsgFifoNoFree(): mReadHead(0), mWriteHead(0) {}
void MakeEmpty() { mReadHead.store(mWriteHead.load()); }
bool IsEmpty() { return mReadHead.load(memory_order_relaxed) == mWriteHead.load(memory_order_relaxed); }
bool HasData() { return mReadHead.load(memory_order_relaxed) != mWriteHead.load(memory_order_relaxed); }
bool Write(MsgType& data) {
unsigned int next = NextPos(mWriteHead.load(memory_order_relaxed));
if (next == mReadHead.load(memory_order_relaxed))
return false; // fifo is full
mItems[next] = data;
mWriteHead.store(next, memory_order_release);
return true;
}
void Perform() // get next and advance
{
while (HasData()) {
unsigned int next = NextPos(mReadHead.load(memory_order_relaxed));
mItems[next].Perform();
mReadHead.store(next, memory_order_release);
}
}
private:
int NextPos(int inPos) { return (inPos + 1) & (N - 1); }
std::atomic<int> mReadHead, mWriteHead;
MsgType mItems[N];
};
}
using SCMsgFifo::MsgFifo;
using SCMsgFifo::MsgFifoNoFree;
/////////////////////////////////////////////////////////////////////
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