1 #ifndef AUDIO_DEVICE_PA_RINGBUFFER_H_ 2 #define AUDIO_DEVICE_PA_RINGBUFFER_H_ 3 /* 4 * $Id: pa_ringbuffer.h 1421 2009-11-18 16:09:05Z bjornroche $ 5 * Portable Audio I/O Library 6 * Ring Buffer utility. 7 * 8 * Author: Phil Burk, http://www.softsynth.com 9 * modified for SMP safety on OS X by Bjorn Roche. 10 * also allowed for const where possible. 11 * modified for multiple-byte-sized data elements by Sven Fischer 12 * 13 * Note that this is safe only for a single-thread reader 14 * and a single-thread writer. 15 * 16 * This program is distributed with the PortAudio Portable Audio Library. 17 * For more information see: http://www.portaudio.com 18 * Copyright (c) 1999-2000 Ross Bencina and Phil Burk 19 * 20 * Permission is hereby granted, free of charge, to any person obtaining 21 * a copy of this software and associated documentation files 22 * (the "Software"), to deal in the Software without restriction, 23 * including without limitation the rights to use, copy, modify, merge, 24 * publish, distribute, sublicense, and/or sell copies of the Software, 25 * and to permit persons to whom the Software is furnished to do so, 26 * subject to the following conditions: 27 * 28 * The above copyright notice and this permission notice shall be 29 * included in all copies or substantial portions of the Software. 30 * 31 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, 32 * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF 33 * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. 34 * IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR 35 * ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF 36 * CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION 37 * WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE. 38 */ 39 40 /* 41 * The text above constitutes the entire PortAudio license; however, 42 * the PortAudio community also makes the following non-binding requests: 43 * 44 * Any person wishing to distribute modifications to the Software is 45 * requested to send the modifications to the original developer so that 46 * they can be incorporated into the canonical version. It is also 47 * requested that these non-binding requests be included along with the 48 * license above. 49 */ 50 51 /** @file 52 @ingroup common_src 53 @brief Single-reader single-writer lock-free ring buffer 54 55 PaUtilRingBuffer is a ring buffer used to transport samples between 56 different execution contexts (threads, OS callbacks, interrupt handlers) 57 without requiring the use of any locks. This only works when there is 58 a single reader and a single writer (ie. one thread or callback writes 59 to the ring buffer, another thread or callback reads from it). 60 61 The PaUtilRingBuffer structure manages a ring buffer containing N 62 elements, where N must be a power of two. An element may be any size 63 (specified in bytes). 64 65 The memory area used to store the buffer elements must be allocated by 66 the client prior to calling PaUtil_InitializeRingBuffer() and must outlive 67 the use of the ring buffer. 68 */ 69 70 #if defined(__APPLE__) 71 #include <sys/types.h> 72 typedef int32_t PaRingBufferSize; 73 #elif defined( __GNUC__ ) 74 typedef long PaRingBufferSize; 75 #elif (_MSC_VER >= 1400) 76 typedef long PaRingBufferSize; 77 #elif defined(_MSC_VER) || defined(__BORLANDC__) 78 typedef long PaRingBufferSize; 79 #else 80 typedef long PaRingBufferSize; 81 #endif 82 83 84 85 #ifdef __cplusplus 86 extern "C" 87 { 88 #endif /* __cplusplus */ 89 90 typedef struct PaUtilRingBuffer 91 { 92 PaRingBufferSize bufferSize; /**< Number of elements in FIFO. Power of 2. Set by PaUtil_InitRingBuffer. */ 93 PaRingBufferSize writeIndex; /**< Index of next writable element. Set by PaUtil_AdvanceRingBufferWriteIndex. */ 94 PaRingBufferSize readIndex; /**< Index of next readable element. Set by PaUtil_AdvanceRingBufferReadIndex. */ 95 PaRingBufferSize bigMask; /**< Used for wrapping indices with extra bit to distinguish full/empty. */ 96 PaRingBufferSize smallMask; /**< Used for fitting indices to buffer. */ 97 PaRingBufferSize elementSizeBytes; /**< Number of bytes per element. */ 98 char *buffer; /**< Pointer to the buffer containing the actual data. */ 99 }PaUtilRingBuffer; 100 101 /** Initialize Ring Buffer. 102 103 @param rbuf The ring buffer. 104 105 @param elementSizeBytes The size of a single data element in bytes. 106 107 @param elementCount The number of elements in the buffer (must be power of 2). 108 109 @param dataPtr A pointer to a previously allocated area where the data 110 will be maintained. It must be elementCount*elementSizeBytes long. 111 112 @return -1 if elementCount is not a power of 2, otherwise 0. 113 */ 114 PaRingBufferSize PaUtil_InitializeRingBuffer( PaUtilRingBuffer *rbuf, PaRingBufferSize elementSizeBytes, PaRingBufferSize elementCount, void *dataPtr ); 115 116 /** Clear buffer. Should only be called when buffer is NOT being read. 117 118 @param rbuf The ring buffer. 119 */ 120 void PaUtil_FlushRingBuffer( PaUtilRingBuffer *rbuf ); 121 122 /** Retrieve the number of elements available in the ring buffer for writing. 123 124 @param rbuf The ring buffer. 125 126 @return The number of elements available for writing. 127 */ 128 PaRingBufferSize PaUtil_GetRingBufferWriteAvailable( PaUtilRingBuffer *rbuf ); 129 130 /** Retrieve the number of elements available in the ring buffer for reading. 131 132 @param rbuf The ring buffer. 133 134 @return The number of elements available for reading. 135 */ 136 PaRingBufferSize PaUtil_GetRingBufferReadAvailable( PaUtilRingBuffer *rbuf ); 137 138 /** Write data to the ring buffer. 139 140 @param rbuf The ring buffer. 141 142 @param data The address of new data to write to the buffer. 143 144 @param elementCount The number of elements to be written. 145 146 @return The number of elements written. 147 */ 148 PaRingBufferSize PaUtil_WriteRingBuffer( PaUtilRingBuffer *rbuf, const void *data, PaRingBufferSize elementCount ); 149 150 /** Read data from the ring buffer. 151 152 @param rbuf The ring buffer. 153 154 @param data The address where the data should be stored. 155 156 @param elementCount The number of elements to be read. 157 158 @return The number of elements read. 159 */ 160 PaRingBufferSize PaUtil_ReadRingBuffer( PaUtilRingBuffer *rbuf, void *data, PaRingBufferSize elementCount ); 161 162 /** Get address of region(s) to which we can write data. 163 164 @param rbuf The ring buffer. 165 166 @param elementCount The number of elements desired. 167 168 @param dataPtr1 The address where the first (or only) region pointer will be 169 stored. 170 171 @param sizePtr1 The address where the first (or only) region length will be 172 stored. 173 174 @param dataPtr2 The address where the second region pointer will be stored if 175 the first region is too small to satisfy elementCount. 176 177 @param sizePtr2 The address where the second region length will be stored if 178 the first region is too small to satisfy elementCount. 179 180 @return The room available to be written or elementCount, whichever is smaller. 181 */ 182 PaRingBufferSize PaUtil_GetRingBufferWriteRegions( PaUtilRingBuffer *rbuf, PaRingBufferSize elementCount, 183 void **dataPtr1, PaRingBufferSize *sizePtr1, 184 void **dataPtr2, PaRingBufferSize *sizePtr2 ); 185 186 /** Advance the write index to the next location to be written. 187 188 @param rbuf The ring buffer. 189 190 @param elementCount The number of elements to advance. 191 192 @return The new position. 193 */ 194 PaRingBufferSize PaUtil_AdvanceRingBufferWriteIndex( PaUtilRingBuffer *rbuf, PaRingBufferSize elementCount ); 195 196 /** Get address of region(s) from which we can write data. 197 198 @param rbuf The ring buffer. 199 200 @param elementCount The number of elements desired. 201 202 @param dataPtr1 The address where the first (or only) region pointer will be 203 stored. 204 205 @param sizePtr1 The address where the first (or only) region length will be 206 stored. 207 208 @param dataPtr2 The address where the second region pointer will be stored if 209 the first region is too small to satisfy elementCount. 210 211 @param sizePtr2 The address where the second region length will be stored if 212 the first region is too small to satisfy elementCount. 213 214 @return The number of elements available for reading. 215 */ 216 PaRingBufferSize PaUtil_GetRingBufferReadRegions( PaUtilRingBuffer *rbuf, PaRingBufferSize elementCount, 217 void **dataPtr1, PaRingBufferSize *sizePtr1, 218 void **dataPtr2, PaRingBufferSize *sizePtr2 ); 219 220 /** Advance the read index to the next location to be read. 221 222 @param rbuf The ring buffer. 223 224 @param elementCount The number of elements to advance. 225 226 @return The new position. 227 */ 228 PaRingBufferSize PaUtil_AdvanceRingBufferReadIndex( PaUtilRingBuffer *rbuf, PaRingBufferSize elementCount ); 229 230 #ifdef __cplusplus 231 } 232 #endif /* __cplusplus */ 233 #endif /* MODULES_AUDIO_DEVICE_MAIN_SOURCE_MAC_PORTAUDIO_PA_RINGBUFFER_H_ */ 234