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/*
* $Id: ringbuffer.c,v 1.18 2007-07-20 03:25:20 millerpuckette Exp $
* ringbuffer.c
* Ring Buffer utility..
*
* Author: Phil Burk, http://www.softsynth.com
*
* This program uses the PortAudio Portable Audio Library.
* For more information see: http://www.audiomulch.com/portaudio/
* Copyright (c) 1999-2000 Ross Bencina and Phil Burk
*
* Permission is hereby granted, free of charge, to any person obtaining
* a copy of this software and associated documentation files
* (the "Software"), to deal in the Software without restriction,
* including without limitation the rights to use, copy, modify, merge,
* publish, distribute, sublicense, and/or sell copies of the Software,
* and to permit persons to whom the Software is furnished to do so,
* subject to the following conditions:
*
* The above copyright notice and this permission notice shall be
* included in all copies or substantial portions of the Software.
*
* Any person wishing to distribute modifications to the Software is
* requested to send the modifications to the original developer so that
* they can be incorporated into the canonical version.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
* EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
* MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
* IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR
* ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF
* CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
* WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
*
*/
#include <stdio.h>
#include <stdlib.h>
#include <math.h>
#include "ringbuffer.h"
#include <string.h>
/***************************************************************************
* Initialize FIFO.
* numBytes must be power of 2, returns -1 if not.
*/
long RingBuffer_Init( RingBuffer *rbuf, long numBytes, void *dataPtr )
{
if( ((numBytes-1) & numBytes) != 0) return -1; /* Not Power of two. */
rbuf->bufferSize = numBytes;
rbuf->buffer = (char *)dataPtr;
RingBuffer_Flush( rbuf );
rbuf->bigMask = (numBytes*2)-1;
rbuf->smallMask = (numBytes)-1;
return 0;
}
/***************************************************************************
** Return number of bytes available for reading. */
long RingBuffer_GetReadAvailable( RingBuffer *rbuf )
{
return ( (rbuf->writeIndex - rbuf->readIndex) & rbuf->bigMask );
}
/***************************************************************************
** Return number of bytes available for writing. */
long RingBuffer_GetWriteAvailable( RingBuffer *rbuf )
{
return ( rbuf->bufferSize - RingBuffer_GetReadAvailable(rbuf));
}
/***************************************************************************
** Clear buffer. Should only be called when buffer is NOT being read. */
void RingBuffer_Flush( RingBuffer *rbuf )
{
rbuf->writeIndex = rbuf->readIndex = 0;
}
/***************************************************************************
** Get address of region(s) to which we can write data.
** If the region is contiguous, size2 will be zero.
** If non-contiguous, size2 will be the size of second region.
** Returns room available to be written or numBytes, whichever is smaller.
*/
long RingBuffer_GetWriteRegions( RingBuffer *rbuf, long numBytes,
void **dataPtr1, long *sizePtr1,
void **dataPtr2, long *sizePtr2 )
{
long index;
long available = RingBuffer_GetWriteAvailable( rbuf );
if( numBytes > available ) numBytes = available;
/* Check to see if write is not contiguous. */
index = rbuf->writeIndex & rbuf->smallMask;
if( (index + numBytes) > rbuf->bufferSize )
{
/* Write data in two blocks that wrap the buffer. */
long firstHalf = rbuf->bufferSize - index;
*dataPtr1 = &rbuf->buffer[index];
*sizePtr1 = firstHalf;
*dataPtr2 = &rbuf->buffer[0];
*sizePtr2 = numBytes - firstHalf;
}
else
{
*dataPtr1 = &rbuf->buffer[index];
*sizePtr1 = numBytes;
*dataPtr2 = NULL;
*sizePtr2 = 0;
}
return numBytes;
}
/***************************************************************************
*/
long RingBuffer_AdvanceWriteIndex( RingBuffer *rbuf, long numBytes )
{
return rbuf->writeIndex = (rbuf->writeIndex + numBytes) & rbuf->bigMask;
}
/***************************************************************************
** Get address of region(s) from which we can read data.
** If the region is contiguous, size2 will be zero.
** If non-contiguous, size2 will be the size of second region.
** Returns room available to be written or numBytes, whichever is smaller.
*/
long RingBuffer_GetReadRegions( RingBuffer *rbuf, long numBytes,
void **dataPtr1, long *sizePtr1,
void **dataPtr2, long *sizePtr2 )
{
long index;
long available = RingBuffer_GetReadAvailable( rbuf );
if( numBytes > available ) numBytes = available;
/* Check to see if read is not contiguous. */
index = rbuf->readIndex & rbuf->smallMask;
if( (index + numBytes) > rbuf->bufferSize )
{
/* Write data in two blocks that wrap the buffer. */
long firstHalf = rbuf->bufferSize - index;
*dataPtr1 = &rbuf->buffer[index];
*sizePtr1 = firstHalf;
*dataPtr2 = &rbuf->buffer[0];
*sizePtr2 = numBytes - firstHalf;
}
else
{
*dataPtr1 = &rbuf->buffer[index];
*sizePtr1 = numBytes;
*dataPtr2 = NULL;
*sizePtr2 = 0;
}
return numBytes;
}
/***************************************************************************
*/
long RingBuffer_AdvanceReadIndex( RingBuffer *rbuf, long numBytes )
{
return rbuf->readIndex = (rbuf->readIndex + numBytes) & rbuf->bigMask;
}
/***************************************************************************
** Return bytes written. */
long RingBuffer_Write( RingBuffer *rbuf, void *data, long numBytes )
{
long size1, size2, numWritten;
void *data1, *data2;
numWritten = RingBuffer_GetWriteRegions( rbuf, numBytes, &data1, &size1, &data2, &size2 );
if( size2 > 0 )
{
memcpy( data1, data, size1 );
data = ((char *)data) + size1;
memcpy( data2, data, size2 );
}
else
{
memcpy( data1, data, size1 );
}
RingBuffer_AdvanceWriteIndex( rbuf, numWritten );
return numWritten;
}
/***************************************************************************
** Return bytes read. */
long RingBuffer_Read( RingBuffer *rbuf, void *data, long numBytes )
{
long size1, size2, numRead;
void *data1, *data2;
numRead = RingBuffer_GetReadRegions( rbuf, numBytes, &data1, &size1, &data2, &size2 );
if( size2 > 0 )
{
memcpy( data, data1, size1 );
data = ((char *)data) + size1;
memcpy( data, data2, size2 );
}
else
{
memcpy( data, data1, size1 );
}
RingBuffer_AdvanceReadIndex( rbuf, numRead );
return numRead;
}
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