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| /* | |
| * $Id$ | |
| * Portable Audio I/O Library | |
| * Ring Buffer utility. | |
| * | |
| * Author: Phil Burk, http://www.softsynth.com | |
| * modified for SMP safety on OS X by Bjorn Roche. | |
| * 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 is distributed with 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 | |
| @brief Single-reader single-writer lock-free ring buffer | |
| PaUtilRingBuffer is a ring buffer used to transport samples between | |
| different execution contexts (threads, OS callbacks, interrupt handlers) | |
| without requiring the use of any locks. This only works when there is | |
| a single reader and a single writer (ie. one thread or callback writes | |
| to the ring buffer, another thread or callback reads from it). | |
| The PaUtilRingBuffer structure manages a ring buffer containing N | |
| elements, where N must be a power of two. An element may be any size | |
| (specified in bytes). | |
| The memory area used to store the buffer elements must be allocated by | |
| the client prior to calling PaUtil_InitializeRingBuffer() and must outlive | |
| the use of the ring buffer. | |
| @note The ring buffer functions are not normally exposed in the PortAudio libraries. | |
| If you want to call them then you will need to add pa_ringbuffer.c to your application source code. | |
| */ | |
| typedef int32_t ring_buffer_size_t; | |
| typedef long ring_buffer_size_t; | |
| typedef long ring_buffer_size_t; | |
| typedef long ring_buffer_size_t; | |
| typedef long ring_buffer_size_t; | |
| extern "C" | |
| { | |
| typedef struct PaUtilRingBuffer | |
| { | |
| ring_buffer_size_t bufferSize; /**< Number of elements in FIFO. Power of 2. Set by PaUtil_InitRingBuffer. */ | |
| volatile ring_buffer_size_t writeIndex; /**< Index of next writable element. Set by PaUtil_AdvanceRingBufferWriteIndex. */ | |
| volatile ring_buffer_size_t readIndex; /**< Index of next readable element. Set by PaUtil_AdvanceRingBufferReadIndex. */ | |
| ring_buffer_size_t bigMask; /**< Used for wrapping indices with extra bit to distinguish full/empty. */ | |
| ring_buffer_size_t smallMask; /**< Used for fitting indices to buffer. */ | |
| ring_buffer_size_t elementSizeBytes; /**< Number of bytes per element. */ | |
| char *buffer; /**< Pointer to the buffer containing the actual data. */ | |
| }PaUtilRingBuffer; | |
| /** Initialize Ring Buffer to empty state ready to have elements written to it. | |
| @param rbuf The ring buffer. | |
| @param elementSizeBytes The size of a single data element in bytes. | |
| @param elementCount The number of elements in the buffer (must be a power of 2). | |
| @param dataPtr A pointer to a previously allocated area where the data | |
| will be maintained. It must be elementCount*elementSizeBytes long. | |
| @return -1 if elementCount is not a power of 2, otherwise 0. | |
| */ | |
| ring_buffer_size_t PaUtil_InitializeRingBuffer( PaUtilRingBuffer *rbuf, ring_buffer_size_t elementSizeBytes, ring_buffer_size_t elementCount, void *dataPtr ); | |
| /** Reset buffer to empty. Should only be called when buffer is NOT being read or written. | |
| @param rbuf The ring buffer. | |
| */ | |
| void PaUtil_FlushRingBuffer( PaUtilRingBuffer *rbuf ); | |
| /** Retrieve the number of elements available in the ring buffer for writing. | |
| @param rbuf The ring buffer. | |
| @return The number of elements available for writing. | |
| */ | |
| ring_buffer_size_t PaUtil_GetRingBufferWriteAvailable( const PaUtilRingBuffer *rbuf ); | |
| /** Retrieve the number of elements available in the ring buffer for reading. | |
| @param rbuf The ring buffer. | |
| @return The number of elements available for reading. | |
| */ | |
| ring_buffer_size_t PaUtil_GetRingBufferReadAvailable( const PaUtilRingBuffer *rbuf ); | |
| /** Write data to the ring buffer. | |
| @param rbuf The ring buffer. | |
| @param data The address of new data to write to the buffer. | |
| @param elementCount The number of elements to be written. | |
| @return The number of elements written. | |
| */ | |
| ring_buffer_size_t PaUtil_WriteRingBuffer( PaUtilRingBuffer *rbuf, const void *data, ring_buffer_size_t elementCount ); | |
| /** Read data from the ring buffer. | |
| @param rbuf The ring buffer. | |
| @param data The address where the data should be stored. | |
| @param elementCount The number of elements to be read. | |
| @return The number of elements read. | |
| */ | |
| ring_buffer_size_t PaUtil_ReadRingBuffer( PaUtilRingBuffer *rbuf, void *data, ring_buffer_size_t elementCount ); | |
| /** Get address of region(s) to which we can write data. | |
| @param rbuf The ring buffer. | |
| @param elementCount The number of elements desired. | |
| @param dataPtr1 The address where the first (or only) region pointer will be | |
| stored. | |
| @param sizePtr1 The address where the first (or only) region length will be | |
| stored. | |
| @param dataPtr2 The address where the second region pointer will be stored if | |
| the first region is too small to satisfy elementCount. | |
| @param sizePtr2 The address where the second region length will be stored if | |
| the first region is too small to satisfy elementCount. | |
| @return The room available to be written or elementCount, whichever is smaller. | |
| */ | |
| ring_buffer_size_t PaUtil_GetRingBufferWriteRegions( PaUtilRingBuffer *rbuf, ring_buffer_size_t elementCount, | |
| void **dataPtr1, ring_buffer_size_t *sizePtr1, | |
| void **dataPtr2, ring_buffer_size_t *sizePtr2 ); | |
| /** Advance the write index to the next location to be written. | |
| @param rbuf The ring buffer. | |
| @param elementCount The number of elements to advance. | |
| @return The new position. | |
| */ | |
| ring_buffer_size_t PaUtil_AdvanceRingBufferWriteIndex( PaUtilRingBuffer *rbuf, ring_buffer_size_t elementCount ); | |
| /** Get address of region(s) from which we can read data. | |
| @param rbuf The ring buffer. | |
| @param elementCount The number of elements desired. | |
| @param dataPtr1 The address where the first (or only) region pointer will be | |
| stored. | |
| @param sizePtr1 The address where the first (or only) region length will be | |
| stored. | |
| @param dataPtr2 The address where the second region pointer will be stored if | |
| the first region is too small to satisfy elementCount. | |
| @param sizePtr2 The address where the second region length will be stored if | |
| the first region is too small to satisfy elementCount. | |
| @return The number of elements available for reading. | |
| */ | |
| ring_buffer_size_t PaUtil_GetRingBufferReadRegions( PaUtilRingBuffer *rbuf, ring_buffer_size_t elementCount, | |
| void **dataPtr1, ring_buffer_size_t *sizePtr1, | |
| void **dataPtr2, ring_buffer_size_t *sizePtr2 ); | |
| /** Advance the read index to the next location to be read. | |
| @param rbuf The ring buffer. | |
| @param elementCount The number of elements to advance. | |
| @return The new position. | |
| */ | |
| ring_buffer_size_t PaUtil_AdvanceRingBufferReadIndex( PaUtilRingBuffer *rbuf, ring_buffer_size_t elementCount ); | |
| } | |