ByteBufferDataIO.h

/* This file is Copyright 2000-2008 Meyer Sound Laboratories Inc.  See the included LICENSE.txt file for details. */

#ifndef MuscleByteBufferDataIO_h
#define MuscleByteBufferDataIO_h

#include "dataio/DataIO.h"
#include "util/ByteBuffer.h"

BEGIN_NAMESPACE(muscle);

class ByteBufferDataIO : public DataIO
{
public:
   ByteBufferDataIO(const ByteBufferRef & buf = ByteBufferRef()) : _buf(buf), _seekPos(0) {/* empty */}

   virtual ~ByteBufferDataIO() {/* empty */}

   void SetBuffer(const ByteBufferRef & buf) {_buf = buf;}

   const ByteBufferRef & GetBuffer() const {return _buf;}

   virtual int32 Read(void * buffer, uint32 size)  
   {
      if (_buf())
      {
         int32 copyBytes = muscleMin((int32)size, muscleMax((int32)0, (int32)(_buf()->GetNumBytes()-_seekPos)));
         memcpy(buffer, _buf()->GetBuffer()+_seekPos, copyBytes);
         _seekPos += copyBytes;
         return copyBytes;
      }
      return -1;
   }

   virtual int32 Write(const void * buffer, uint32 size) 
   {
      if (_buf() == NULL) return -1;

      uint32 oldBufSize = _buf()->GetNumBytes();
      uint32 pastOffset = muscleMax(oldBufSize, _seekPos+size);
      if (pastOffset > oldBufSize)
      {
         uint32 preallocBytes = (pastOffset*2);  // exponential resize to avoid too many reallocs
         if (_buf()->SetNumBytes(preallocBytes, true) != B_NO_ERROR) return -1;   // allocate the memory
         memset(_buf()->GetBuffer()+oldBufSize, 0, preallocBytes-oldBufSize);  // make sure newly alloc'd memory is zeroed out!
         (void) _buf()->SetNumBytes(pastOffset, true);  // guaranteed not to fail
      }
      
      memcpy(_buf()->GetBuffer()+_seekPos, buffer, size);
      _seekPos += size;
      return size;
   }

   virtual status_t Seek(int64 offset, int whence)
   {
      uint32 fileLen = _buf() ? _buf()->GetNumBytes() : 0;
      int32 o = (int32) offset;
      int32 newSeekPos = -1;
      switch(whence)
      {
         case IO_SEEK_SET:  newSeekPos = o;          break;
         case IO_SEEK_CUR:  newSeekPos = _seekPos+o; break;
         case IO_SEEK_END:  newSeekPos = fileLen-o;  break;
         default:           return B_ERROR;
      }
      if (newSeekPos < 0) return B_ERROR;
      _seekPos = newSeekPos;
      return B_NO_ERROR;
   }
   
   virtual int64 GetPosition() const {return _seekPos;}

   virtual void FlushOutput() {/* empty */}

   virtual void Shutdown() {_buf.Reset();}

   virtual const SocketRef & GetSelectSocket() const {return GetNullSocket();}

private:
   ByteBufferRef _buf;
   int32 _seekPos;
};

END_NAMESPACE(muscle);

#endif

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