moved trunk into place
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bjornroche
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src/common/pa_ringbuffer.h
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src/common/pa_ringbuffer.h
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#ifndef PA_RINGBUFFER_H
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#define PA_RINGBUFFER_H
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/*
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* $Id$
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* Portable Audio I/O Library
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* Ring Buffer utility.
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*
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* Author: Phil Burk, http://www.softsynth.com
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* modified for SMP safety on OS X by Bjorn Roche.
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* also allowed for const where possible.
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* modified for multiple-byte-sized data elements by Sven Fischer
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*
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* Note that this is safe only for a single-thread reader
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* and a single-thread writer.
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*
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* This program is distributed with 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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*
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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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*
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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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*
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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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*/
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/*
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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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*
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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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* license above.
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*/
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/** @file
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@ingroup common_src
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@brief Single-reader single-writer lock-free ring buffer
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PaUtilRingBuffer is a ring buffer used to transport samples between
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different execution contexts (threads, OS callbacks, interrupt handlers)
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without requiring the use of any locks. This only works when there is
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a single reader and a single writer (ie. one thread or callback writes
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to the ring buffer, another thread or callback reads from it).
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The PaUtilRingBuffer structure manages a ring buffer containing N
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elements, where N must be a power of two. An element may be any size
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(specified in bytes).
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The memory area used to store the buffer elements must be allocated by
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the client prior to calling PaUtil_InitializeRingBuffer() and must outlive
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the use of the ring buffer.
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*/
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#ifdef __cplusplus
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extern "C"
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{
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#endif /* __cplusplus */
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typedef struct PaUtilRingBuffer
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{
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long bufferSize; /**< Number of elements in FIFO. Power of 2. Set by PaUtil_InitRingBuffer. */
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long writeIndex; /**< Index of next writable element. Set by PaUtil_AdvanceRingBufferWriteIndex. */
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long readIndex; /**< Index of next readable element. Set by PaUtil_AdvanceRingBufferReadIndex. */
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long bigMask; /**< Used for wrapping indices with extra bit to distinguish full/empty. */
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long smallMask; /**< Used for fitting indices to buffer. */
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long elementSizeBytes; /**< Number of bytes per element. */
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char *buffer; /**< Pointer to the buffer containing the actual data. */
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}PaUtilRingBuffer;
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/** Initialize Ring Buffer.
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@param rbuf The ring buffer.
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@param elementSizeBytes The size of a single data element in bytes.
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@param elementCount The number of elements in the buffer (must be power of 2).
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@param dataPtr A pointer to a previously allocated area where the data
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will be maintained. It must be elementCount*elementSizeBytes long.
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@return -1 if elementCount is not a power of 2, otherwise 0.
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*/
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long PaUtil_InitializeRingBuffer( PaUtilRingBuffer *rbuf, long elementSizeBytes, long elementCount, void *dataPtr );
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/** Clear buffer. Should only be called when buffer is NOT being read.
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@param rbuf The ring buffer.
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*/
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void PaUtil_FlushRingBuffer( PaUtilRingBuffer *rbuf );
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/** Retrieve the number of elements available in the ring buffer for writing.
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@param rbuf The ring buffer.
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@return The number of elements available for writing.
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*/
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long PaUtil_GetRingBufferWriteAvailable( PaUtilRingBuffer *rbuf );
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/** Retrieve the number of elements available in the ring buffer for reading.
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@param rbuf The ring buffer.
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@return The number of elements available for reading.
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*/
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long PaUtil_GetRingBufferReadAvailable( PaUtilRingBuffer *rbuf );
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/** Write data to the ring buffer.
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@param rbuf The ring buffer.
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@param data The address of new data to write to the buffer.
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@param elementCount The number of elements to be written.
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@return The number of elements written.
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*/
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long PaUtil_WriteRingBuffer( PaUtilRingBuffer *rbuf, const void *data, long elementCount );
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/** Read data from the ring buffer.
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@param rbuf The ring buffer.
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@param data The address where the data should be stored.
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@param elementCount The number of elements to be read.
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@return The number of elements read.
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*/
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long PaUtil_ReadRingBuffer( PaUtilRingBuffer *rbuf, void *data, long elementCount );
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/** Get address of region(s) to which we can write data.
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@param rbuf The ring buffer.
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@param elementCount The number of elements desired.
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@param dataPtr1 The address where the first (or only) region pointer will be
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stored.
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@param sizePtr1 The address where the first (or only) region length will be
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stored.
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@param dataPtr2 The address where the second region pointer will be stored if
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the first region is too small to satisfy elementCount.
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@param sizePtr2 The address where the second region length will be stored if
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the first region is too small to satisfy elementCount.
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@return The room available to be written or elementCount, whichever is smaller.
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*/
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long PaUtil_GetRingBufferWriteRegions( PaUtilRingBuffer *rbuf, long elementCount,
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void **dataPtr1, long *sizePtr1,
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void **dataPtr2, long *sizePtr2 );
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/** Advance the write index to the next location to be written.
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@param rbuf The ring buffer.
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@param elementCount The number of elements to advance.
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@return The new position.
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*/
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long PaUtil_AdvanceRingBufferWriteIndex( PaUtilRingBuffer *rbuf, long elementCount );
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/** Get address of region(s) from which we can write data.
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@param rbuf The ring buffer.
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@param elementCount The number of elements desired.
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@param dataPtr1 The address where the first (or only) region pointer will be
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stored.
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@param sizePtr1 The address where the first (or only) region length will be
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stored.
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@param dataPtr2 The address where the second region pointer will be stored if
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the first region is too small to satisfy elementCount.
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@param sizePtr2 The address where the second region length will be stored if
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the first region is too small to satisfy elementCount.
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@return The number of elements available for reading.
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*/
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long PaUtil_GetRingBufferReadRegions( PaUtilRingBuffer *rbuf, long elementCount,
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void **dataPtr1, long *sizePtr1,
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void **dataPtr2, long *sizePtr2 );
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/** Advance the read index to the next location to be read.
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@param rbuf The ring buffer.
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@param elementCount The number of elements to advance.
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@return The new position.
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*/
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long PaUtil_AdvanceRingBufferReadIndex( PaUtilRingBuffer *rbuf, long elementCount );
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#ifdef __cplusplus
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}
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#endif /* __cplusplus */
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#endif /* PA_RINGBUFFER_H */
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