[6d9958]: portaudio / src / common / pa_ringbuffer.c  Maximize  Restore  History

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/*
* $Id: pa_ringbuffer.c 1346 2008-02-20 10:09:20Z rossb $
* Portable Audio I/O Library
* Ring Buffer utility.
*
* Author: Phil Burk, http://www.softsynth.com
* modified for SMP safety on Mac OS X by Bjorn Roche
* modified for SMP safety on Linux by Leland Lucius
* also, allowed for const where possible
* modified for multiple-byte-sized data elements by Sven Fischer
*
* Note that this is safe only for a single-thread reader and a
* single-thread writer.
*
* This program uses the PortAudio Portable Audio Library.
* For more information see: http://www.portaudio.com
* 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.
*
* 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.
*/
/*
* The text above constitutes the entire PortAudio license; however,
* the PortAudio community also makes the following non-binding requests:
*
* 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. It is also
* requested that these non-binding requests be included along with the
* license above.
*/
/**
@file
@ingroup common_src
*/
#include <stdio.h>
#include <stdlib.h>
#include <math.h>
#include "pa_ringbuffer.h"
#include <string.h>
#include "pa_memorybarrier.h"
/***************************************************************************
* Initialize FIFO.
* elementCount must be power of 2, returns -1 if not.
*/
long PaUtil_InitializeRingBuffer( PaUtilRingBuffer *rbuf, long elementSizeBytes, long elementCount, void *dataPtr )
{
if( ((elementCount-1) & elementCount) != 0) return -1; /* Not Power of two. */
rbuf->bufferSize = elementCount;
rbuf->buffer = (char *)dataPtr;
PaUtil_FlushRingBuffer( rbuf );
rbuf->bigMask = (elementCount*2)-1;
rbuf->smallMask = (elementCount)-1;
rbuf->elementSizeBytes = elementSizeBytes;
return 0;
}
/***************************************************************************
** Return number of elements available for reading. */
long PaUtil_GetRingBufferReadAvailable( PaUtilRingBuffer *rbuf )
{
PaUtil_ReadMemoryBarrier();
return ( (rbuf->writeIndex - rbuf->readIndex) & rbuf->bigMask );
}
/***************************************************************************
** Return number of elements available for writing. */
long PaUtil_GetRingBufferWriteAvailable( PaUtilRingBuffer *rbuf )
{
/* Since we are calling PaUtil_GetRingBufferReadAvailable, we don't need an aditional MB */
return ( rbuf->bufferSize - PaUtil_GetRingBufferReadAvailable(rbuf));
}
/***************************************************************************
** Clear buffer. Should only be called when buffer is NOT being read. */
void PaUtil_FlushRingBuffer( PaUtilRingBuffer *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 elementCount, whichever is smaller.
*/
long PaUtil_GetRingBufferWriteRegions( PaUtilRingBuffer *rbuf, long elementCount,
void **dataPtr1, long *sizePtr1,
void **dataPtr2, long *sizePtr2 )
{
long index;
long available = PaUtil_GetRingBufferWriteAvailable( rbuf );
if( elementCount > available ) elementCount = available;
/* Check to see if write is not contiguous. */
index = rbuf->writeIndex & rbuf->smallMask;
if( (index + elementCount) > rbuf->bufferSize )
{
/* Write data in two blocks that wrap the buffer. */
long firstHalf = rbuf->bufferSize - index;
*dataPtr1 = &rbuf->buffer[index*rbuf->elementSizeBytes];
*sizePtr1 = firstHalf;
*dataPtr2 = &rbuf->buffer[0];
*sizePtr2 = elementCount - firstHalf;
}
else
{
*dataPtr1 = &rbuf->buffer[index*rbuf->elementSizeBytes];
*sizePtr1 = elementCount;
*dataPtr2 = NULL;
*sizePtr2 = 0;
}
return elementCount;
}
/***************************************************************************
*/
long PaUtil_AdvanceRingBufferWriteIndex( PaUtilRingBuffer *rbuf, long elementCount )
{
/* we need to ensure that previous writes are seen before we update the write index */
PaUtil_WriteMemoryBarrier();
return rbuf->writeIndex = (rbuf->writeIndex + elementCount) & 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 elementCount, whichever is smaller.
*/
long PaUtil_GetRingBufferReadRegions( PaUtilRingBuffer *rbuf, long elementCount,
void **dataPtr1, long *sizePtr1,
void **dataPtr2, long *sizePtr2 )
{
long index;
long available = PaUtil_GetRingBufferReadAvailable( rbuf );
if( elementCount > available ) elementCount = available;
/* Check to see if read is not contiguous. */
index = rbuf->readIndex & rbuf->smallMask;
if( (index + elementCount) > rbuf->bufferSize )
{
/* Write data in two blocks that wrap the buffer. */
long firstHalf = rbuf->bufferSize - index;
*dataPtr1 = &rbuf->buffer[index*rbuf->elementSizeBytes];
*sizePtr1 = firstHalf;
*dataPtr2 = &rbuf->buffer[0];
*sizePtr2 = elementCount - firstHalf;
}
else
{
*dataPtr1 = &rbuf->buffer[index*rbuf->elementSizeBytes];
*sizePtr1 = elementCount;
*dataPtr2 = NULL;
*sizePtr2 = 0;
}
return elementCount;
}
/***************************************************************************
*/
long PaUtil_AdvanceRingBufferReadIndex( PaUtilRingBuffer *rbuf, long elementCount )
{
/* we need to ensure that previous writes are always seen before updating the index. */
PaUtil_WriteMemoryBarrier();
return rbuf->readIndex = (rbuf->readIndex + elementCount) & rbuf->bigMask;
}
/***************************************************************************
** Return elements written. */
long PaUtil_WriteRingBuffer( PaUtilRingBuffer *rbuf, const void *data, long elementCount )
{
long size1, size2, numWritten;
void *data1, *data2;
numWritten = PaUtil_GetRingBufferWriteRegions( rbuf, elementCount, &data1, &size1, &data2, &size2 );
if( size2 > 0 )
{
memcpy( data1, data, size1*rbuf->elementSizeBytes );
data = ((char *)data) + size1*rbuf->elementSizeBytes;
memcpy( data2, data, size2*rbuf->elementSizeBytes );
}
else
{
memcpy( data1, data, size1*rbuf->elementSizeBytes );
}
PaUtil_AdvanceRingBufferWriteIndex( rbuf, numWritten );
return numWritten;
}
/***************************************************************************
** Return elements read. */
long PaUtil_ReadRingBuffer( PaUtilRingBuffer *rbuf, void *data, long elementCount )
{
long size1, size2, numRead;
void *data1, *data2;
numRead = PaUtil_GetRingBufferReadRegions( rbuf, elementCount, &data1, &size1, &data2, &size2 );
if( size2 > 0 )
{
memcpy( data, data1, size1*rbuf->elementSizeBytes );
data = ((char *)data) + size1*rbuf->elementSizeBytes;
memcpy( data, data2, size2*rbuf->elementSizeBytes );
}
else
{
memcpy( data, data1, size1*rbuf->elementSizeBytes );
}
PaUtil_AdvanceRingBufferReadIndex( rbuf, numRead );
return numRead;
}

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