RingBuffer.cpp

#include "RingBuffer.h"

RingBuffer::RingBuffer(sampleFormat format, int size)
{
   mFormat = format;
   mBufferSize = (size > 64? size: 64);
   mStart = 0;
   mEnd = 0;
   mBuffer = NewSamples(mBufferSize, mFormat);
}

RingBuffer::~RingBuffer()
{
   DeleteSamples(mBuffer);
}

int RingBuffer::Len()
{
   return (mEnd + mBufferSize - mStart) % mBufferSize;
}

//
// For the writer only:
//

int RingBuffer::AvailForPut()
{
   return (mBufferSize-4) - Len();
}

int RingBuffer::Put(samplePtr buffer, sampleFormat format,
                    int samplesToCopy)
{
   samplePtr src;
   int block;
   int copied;
   int pos;
   int len = Len();

   if (samplesToCopy > (mBufferSize-4) - len)
      samplesToCopy = (mBufferSize-4) - len;

   src = buffer;
   copied = 0;
   pos = mEnd;

   while(samplesToCopy) {
      block = samplesToCopy;
      if (block > mBufferSize - pos)
         block = mBufferSize - pos;

      CopySamples(src, format,
                  mBuffer + pos * SAMPLE_SIZE(mFormat), mFormat,
                  block);

      src += block * SAMPLE_SIZE(format);
      pos = (pos + block) % mBufferSize;
      samplesToCopy -= block;
      copied += block;
   }

   mEnd = pos;

   return copied;
}

//
// For the reader only:
//

int RingBuffer::AvailForGet()
{
   return Len();
}

int RingBuffer::Get(samplePtr buffer, sampleFormat format,
                    int samplesToCopy)
{
   samplePtr dest;
   int block;
   int copied;
   int len = Len();

   if (samplesToCopy > len)
      samplesToCopy = len;

   dest = buffer;
   copied = 0;

   while(samplesToCopy) {
      block = samplesToCopy;
      if (block > mBufferSize - mStart)
         block = mBufferSize - mStart;

      CopySamples(mBuffer + mStart * SAMPLE_SIZE(mFormat), mFormat,
                  dest, format,
                  block);

      dest += block * SAMPLE_SIZE(mFormat);
      mStart = (mStart + block) % mBufferSize;
      samplesToCopy -= block;
      copied += block;
   }

   return copied;
}

int RingBuffer::Discard(int samplesToDiscard)
{
   int len = Len();

   if (samplesToDiscard > len)
      samplesToDiscard = len;

   mStart = (mStart + samplesToDiscard) % mBufferSize;

   return samplesToDiscard;
}