include/common/SC_FIFO.h

   1 /*
   2         SuperCollider real time audio synthesis system
   3     Copyright (c) 2002 James McCartney. All rights reserved.
   4         http://www.audiosynth.com
   5
   6     This program is free software; you can redistribute it and/or modify
   7     it under the terms of the GNU General Public License as published by
   8     the Free Software Foundation; either version 2 of the License, or
   9     (at your option) any later version.
  10
  11     This program is distributed in the hope that it will be useful,
  12     but WITHOUT ANY WARRANTY; without even the implied warranty of
  13     MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  14     GNU General Public License for more details.
  15
  16     You should have received a copy of the GNU General Public License
  17     along with this program; if not, write to the Free Software
  18     Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301  USA
  19 */
  20
  21 #ifndef SC_FIFO_H_INCLUDED
  22 #define SC_FIFO_H_INCLUDED
  23
  24 #ifdef __APPLE__
  25 # include <libkern/OSAtomic.h>
  26 #endif
  27
  28 #ifdef _WIN32
  29 # include <winsock2.h>
  30 # include <windows.h>
  31 #endif
  32
  33 template <class T, int N>
  34 class SC_FIFO
  35 {
  36 public:
  37         SC_FIFO()
  38                 : mMask(N - 1),
  39                   mReadHead(0),
  40                   mWriteHead(0)
  41         {}
  42
  43         void MakeEmpty() { mReadHead = mWriteHead; }
  44         bool IsEmpty() { return mReadHead == mWriteHead; }
  45         bool HasData() { return mReadHead != mWriteHead; }
  46
  47         bool Put(T data)
  48         {
  49                 long next = NextPos(mWriteHead);
  50                 if (next == mReadHead) return false; // fifo is full
  51                 mItems[next] = data;
  52 #ifdef __APPLE__
  53                 // we don't really need a compare and swap, but this happens to call
  54                 // the PowerPC memory barrier instruction lwsync.
  55                 OSAtomicCompareAndSwap32Barrier(mWriteHead, next, &mWriteHead);
  56 #elif defined(_WIN32)
  57                 InterlockedExchange(reinterpret_cast<volatile LONG*>(&mWriteHead),next);
  58 #else
  59                 mWriteHead = next;
  60 #endif
  61                 return true;
  62         }
  63
  64         T Get()
  65         {
  66                 //assert(HasData());
  67                 long next = NextPos(mReadHead);
  68                 T out = mItems[next];
  69 #ifdef __APPLE__
  70                 // we don't really need a compare and swap, but this happens to call
  71                 // the PowerPC memory barrier instruction lwsync.
  72                 OSAtomicCompareAndSwap32Barrier(mReadHead, next, &mReadHead);
  73 #elif  defined(_WIN32)
  74                 InterlockedExchange(reinterpret_cast<volatile LONG*>(&mReadHead),next);
  75 #else
  76                 mReadHead = next;
  77 #endif
  78                 return out;
  79         }
  80
  81         int Capacity() const { return N; }
  82
  83 private:
  84         int NextPos(int inPos) { return (inPos + 1) & mMask; }
  85
  86         long mMask;
  87
  88 #ifdef __APPLE__
  89         int32_t mReadHead, mWriteHead;
  90 #else
  91         volatile int mReadHead, mWriteHead;
  92 #endif
  93         T mItems[N];
  94 };
  95
  96 #endif // SC_FIFO_H_INCLUDED