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* $Id: ringbuffer.c,v 1.4 2006/09/23 18:42:46 llucius Exp $
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* Ring Buffer utility..
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* Author: Phil Burk, http://www.softsynth.com
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* This program uses the PortAudio Portable Audio Library.
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* For more information see: http://www.portaudio.com
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* Copyright (c) 1999-2000 Ross Bencina and Phil Burk
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* Permission is hereby granted, free of charge, to any person obtaining
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* a copy of this software and associated documentation files
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* (the "Software"), to deal in the Software without restriction,
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* including without limitation the rights to use, copy, modify, merge,
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* publish, distribute, sublicense, and/or sell copies of the Software,
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* and to permit persons to whom the Software is furnished to do so,
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* subject to the following conditions:
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* The above copyright notice and this permission notice shall be
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* included in all copies or substantial portions of the Software.
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* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
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* EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
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* MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
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* IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR
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* ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF
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* CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
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* WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
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* The text above constitutes the entire PortAudio license; however,
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* the PortAudio community also makes the following non-binding requests:
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* Any person wishing to distribute modifications to the Software is
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* requested to send the modifications to the original developer so that
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* they can be incorporated into the canonical version. It is also
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* requested that these non-binding requests be included along with the
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#include "ringbuffer.h"
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/***************************************************************************
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* numBytes must be power of 2, returns -1 if not.
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long RingBuffer_Init( RingBuffer *rbuf, long numBytes, void *dataPtr )
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if( ((numBytes-1) & numBytes) != 0) return -1; /* Not Power of two. */
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rbuf->bufferSize = numBytes;
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rbuf->buffer = (char *)dataPtr;
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RingBuffer_Flush( rbuf );
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rbuf->bigMask = (numBytes*2)-1;
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rbuf->smallMask = (numBytes)-1;
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/***************************************************************************
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** Return number of bytes available for reading. */
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long RingBuffer_GetReadAvailable( RingBuffer *rbuf )
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return ( (rbuf->writeIndex - rbuf->readIndex) & rbuf->bigMask );
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/***************************************************************************
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** Return number of bytes available for writing. */
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long RingBuffer_GetWriteAvailable( RingBuffer *rbuf )
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return ( rbuf->bufferSize - RingBuffer_GetReadAvailable(rbuf));
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/***************************************************************************
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** Clear buffer. Should only be called when buffer is NOT being read. */
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void RingBuffer_Flush( RingBuffer *rbuf )
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rbuf->writeIndex = rbuf->readIndex = 0;
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/***************************************************************************
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** Get address of region(s) to which we can write data.
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** If the region is contiguous, size2 will be zero.
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** If non-contiguous, size2 will be the size of second region.
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** Returns room available to be written or numBytes, whichever is smaller.
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long RingBuffer_GetWriteRegions( RingBuffer *rbuf, long numBytes,
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void **dataPtr1, long *sizePtr1,
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void **dataPtr2, long *sizePtr2 )
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long available = RingBuffer_GetWriteAvailable( rbuf );
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if( numBytes > available ) numBytes = available;
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/* Check to see if write is not contiguous. */
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index = rbuf->writeIndex & rbuf->smallMask;
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if( (index + numBytes) > rbuf->bufferSize )
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/* Write data in two blocks that wrap the buffer. */
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long firstHalf = rbuf->bufferSize - index;
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*dataPtr1 = &rbuf->buffer[index];
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*sizePtr1 = firstHalf;
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*dataPtr2 = &rbuf->buffer[0];
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*sizePtr2 = numBytes - firstHalf;
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*dataPtr1 = &rbuf->buffer[index];
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*sizePtr1 = numBytes;
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/***************************************************************************
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long RingBuffer_AdvanceWriteIndex( RingBuffer *rbuf, long numBytes )
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return rbuf->writeIndex = (rbuf->writeIndex + numBytes) & rbuf->bigMask;
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/***************************************************************************
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** Get address of region(s) from which we can read data.
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** If the region is contiguous, size2 will be zero.
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** If non-contiguous, size2 will be the size of second region.
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** Returns room available to be written or numBytes, whichever is smaller.
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long RingBuffer_GetReadRegions( RingBuffer *rbuf, long numBytes,
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void **dataPtr1, long *sizePtr1,
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void **dataPtr2, long *sizePtr2 )
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long available = RingBuffer_GetReadAvailable( rbuf );
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if( numBytes > available ) numBytes = available;
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/* Check to see if read is not contiguous. */
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index = rbuf->readIndex & rbuf->smallMask;
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if( (index + numBytes) > rbuf->bufferSize )
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/* Write data in two blocks that wrap the buffer. */
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long firstHalf = rbuf->bufferSize - index;
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*dataPtr1 = &rbuf->buffer[index];
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*sizePtr1 = firstHalf;
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*dataPtr2 = &rbuf->buffer[0];
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*sizePtr2 = numBytes - firstHalf;
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*dataPtr1 = &rbuf->buffer[index];
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*sizePtr1 = numBytes;
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/***************************************************************************
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long RingBuffer_AdvanceReadIndex( RingBuffer *rbuf, long numBytes )
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return rbuf->readIndex = (rbuf->readIndex + numBytes) & rbuf->bigMask;
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/***************************************************************************
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** Return bytes written. */
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long RingBuffer_Write( RingBuffer *rbuf, void *data, long numBytes )
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long size1, size2, numWritten;
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numWritten = RingBuffer_GetWriteRegions( rbuf, numBytes, &data1, &size1, &data2, &size2 );
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memcpy( data1, data, size1 );
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data = ((char *)data) + size1;
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memcpy( data2, data, size2 );
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memcpy( data1, data, size1 );
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RingBuffer_AdvanceWriteIndex( rbuf, numWritten );
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/***************************************************************************
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** Return bytes read. */
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long RingBuffer_Read( RingBuffer *rbuf, void *data, long numBytes )
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long size1, size2, numRead;
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numRead = RingBuffer_GetReadRegions( rbuf, numBytes, &data1, &size1, &data2, &size2 );
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memcpy( data, data1, size1 );
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data = ((char *)data) + size1;
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memcpy( data, data2, size2 );
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memcpy( data, data1, size1 );
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RingBuffer_AdvanceReadIndex( rbuf, numRead );
added
removed
lib-src/portaudio-v19/pablio/ringbuffer.c
