Added pa_ringbuffer as external

5 files changed, 611 insertions, 4 deletions

diff --git a/Makefile b/Makefile
index 06328f0..2bf4c85 100644
--- a/Makefile
+++ b/Makefile
@@ -2,8 +2,11 @@ PORTAUDIOCFLAGS=$(shell pkg-config --cflags portaudiocpp)
 PORTAUDIOLIBS=$(shell pkg-config --libs portaudiocpp)
 
 CXX=clang++-7
-CXXFLAGS=-stdlib=libc++ -Wall -O2 -std=c++17 -fexceptions
+CXXFLAGS=-stdlib=libc++ -Wall -O2 -std=c++17 -fexceptions -Iexternal
 #-march=native -mtune=native # is not better for llvm
+CXXTESTFLAGS=-I/usr/src/googletest/googletest/include -I/usr/src/googletest/googlemock/include
+CC=clang
+CFLAGS=-Wall -O2 -Iexternal
 
 # libstdc++-8 doesn't have transform_reduce
 #CXX=g++-8
@@ -15,7 +18,7 @@ PREFIX=/usr/local/bin
 
 all: tunerdemo testsuite
 
-tunerdemo: audioio.o util.o fft.o autocorrelation.o tuner.o tunerdemo.o
+tunerdemo: audioio.o external/pa_ringbuffer.o util.o fft.o autocorrelation.o tuner.o tunerdemo.o
 	$(CXX) $(CXXFLAGS) $(PORTAUDIOLIBS) -o $@ $^
 
 testsuite: util.o fft.o autocorrelation.o tuner.o testsuite.o
@@ -36,6 +39,9 @@ util.o: util.cpp util.h
 audioio.o: audioio.cpp audioio.h
 	$(CXX) $(CXXFLAGS) $(PORTAUDIOCFLAGS) -c -o $@ $<
 
+external/pa_ringbuffer.o: external/pa_ringbuffer.c external/pa_ringbuffer.h
+	$(CC) $(CFLAGS) -c -o $@ $<
+
 testsuite.o: testsuite.cpp fft.h autocorrelation.h tuner.h
 	$(CXX) $(CXXFLAGS) -c -o $@ $<
 
@@ -49,6 +55,6 @@ install:
 	install tunerdemo $(DESTDIR)/$(PREFIX)/tunerdemo
 
 clean:
-	rm -f tunerdemo *.o
+	rm -f tunerdemo *.o external/*.o
 
 .PHONY: clean install all test
diff --git a/debian/control b/debian/control
index e89c3a3..4dbcf7f 100644
--- a/debian/control
+++ b/debian/control
@@ -1,2 +1,2 @@
 Package: rit-fft
-Build-Depends: g++, clang, portaudio19-dev
+Build-Depends: g++, clang, portaudio19-dev, googletest
diff --git a/external/pa_memorybarrier.h b/external/pa_memorybarrier.h
new file mode 100644
index 0000000..2879ce3
--- /dev/null
+++ b/external/pa_memorybarrier.h
@@ -0,0 +1,128 @@
+/*
+ * $Id: pa_memorybarrier.h 1240 2007-07-17 13:05:07Z bjornroche $
+ * Portable Audio I/O Library
+ * Memory barrier utilities
+ *
+ * Author: Bjorn Roche, XO Audio, LLC
+ *
+ * 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 pa_memorybarrier.h
+ @ingroup common_src
+*/
+
+/****************
+ * Some memory barrier primitives based on the system.
+ * right now only OS X, FreeBSD, and Linux are supported. In addition to providing
+ * memory barriers, these functions should ensure that data cached in registers
+ * is written out to cache where it can be snooped by other CPUs. (ie, the volatile
+ * keyword should not be required)
+ *
+ * the primitives that must be defined are:
+ *
+ * PaUtil_FullMemoryBarrier()
+ * PaUtil_ReadMemoryBarrier()
+ * PaUtil_WriteMemoryBarrier()
+ *
+ ****************/
+
+#if defined(__APPLE__)
+#   include <libkern/OSAtomic.h>
+    /* Here are the memory barrier functions. Mac OS X only provides
+       full memory barriers, so the three types of barriers are the same,
+       however, these barriers are superior to compiler-based ones. */
+#   define PaUtil_FullMemoryBarrier()  OSMemoryBarrier()
+#   define PaUtil_ReadMemoryBarrier()  OSMemoryBarrier()
+#   define PaUtil_WriteMemoryBarrier() OSMemoryBarrier()
+#elif defined(__GNUC__)
+    /* GCC >= 4.1 has built-in intrinsics. We'll use those */
+#   if (__GNUC__ > 4) || (__GNUC__ == 4 && __GNUC_MINOR__ >= 1)
+#      define PaUtil_FullMemoryBarrier()  __sync_synchronize()
+#      define PaUtil_ReadMemoryBarrier()  __sync_synchronize()
+#      define PaUtil_WriteMemoryBarrier() __sync_synchronize()
+    /* as a fallback, GCC understands volatile asm and "memory" to mean it
+     * should not reorder memory read/writes */
+    /* Note that it is not clear that any compiler actually defines __PPC__,
+     * it can probably removed safely. */
+#   elif defined( __ppc__ ) || defined( __powerpc__) || defined( __PPC__ )
+#      define PaUtil_FullMemoryBarrier()  asm volatile("sync":::"memory")
+#      define PaUtil_ReadMemoryBarrier()  asm volatile("sync":::"memory")
+#      define PaUtil_WriteMemoryBarrier() asm volatile("sync":::"memory")
+#   elif defined( __i386__ ) || defined( __i486__ ) || defined( __i586__ ) || \
+         defined( __i686__ ) || defined( __x86_64__ )
+#      define PaUtil_FullMemoryBarrier()  asm volatile("mfence":::"memory")
+#      define PaUtil_ReadMemoryBarrier()  asm volatile("lfence":::"memory")
+#      define PaUtil_WriteMemoryBarrier() asm volatile("sfence":::"memory")
+#   else
+#      ifdef ALLOW_SMP_DANGERS
+#         warning Memory barriers not defined on this system or system unknown
+#         warning For SMP safety, you should fix this.
+#         define PaUtil_FullMemoryBarrier()
+#         define PaUtil_ReadMemoryBarrier()
+#         define PaUtil_WriteMemoryBarrier()
+#      else
+#         error Memory barriers are not defined on this system. You can still compile by defining ALLOW_SMP_DANGERS, but SMP safety will not be guaranteed.
+#      endif
+#   endif
+#elif (_MSC_VER >= 1400) && !defined(_WIN32_WCE)
+#   include <intrin.h>
+#   pragma intrinsic(_ReadWriteBarrier)
+#   pragma intrinsic(_ReadBarrier)
+#   pragma intrinsic(_WriteBarrier)
+/* note that MSVC intrinsics _ReadWriteBarrier(), _ReadBarrier(), _WriteBarrier() are just compiler barriers *not* memory barriers */
+#   define PaUtil_FullMemoryBarrier()  _ReadWriteBarrier()
+#   define PaUtil_ReadMemoryBarrier()  _ReadBarrier()
+#   define PaUtil_WriteMemoryBarrier() _WriteBarrier()
+#elif defined(_WIN32_WCE)
+#   define PaUtil_FullMemoryBarrier()
+#   define PaUtil_ReadMemoryBarrier()
+#   define PaUtil_WriteMemoryBarrier()
+#elif defined(_MSC_VER) || defined(__BORLANDC__)
+#   define PaUtil_FullMemoryBarrier()  _asm { lock add    [esp], 0 }
+#   define PaUtil_ReadMemoryBarrier()  _asm { lock add    [esp], 0 }
+#   define PaUtil_WriteMemoryBarrier() _asm { lock add    [esp], 0 }
+#else
+#   ifdef ALLOW_SMP_DANGERS
+#      warning Memory barriers not defined on this system or system unknown
+#      warning For SMP safety, you should fix this.
+#      define PaUtil_FullMemoryBarrier()
+#      define PaUtil_ReadMemoryBarrier()
+#      define PaUtil_WriteMemoryBarrier()
+#   else
+#      error Memory barriers are not defined on this system. You can still compile by defining ALLOW_SMP_DANGERS, but SMP safety will not be guaranteed.
+#   endif
+#endif
diff --git a/external/pa_ringbuffer.c b/external/pa_ringbuffer.c
new file mode 100644
index 0000000..93b3e43
--- /dev/null
+++ b/external/pa_ringbuffer.c
@@ -0,0 +1,237 @@
+/*
+ * $Id$
+ * 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.
+ */
+ring_buffer_size_t PaUtil_InitializeRingBuffer( PaUtilRingBuffer *rbuf, ring_buffer_size_t elementSizeBytes, ring_buffer_size_t 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. */
+ring_buffer_size_t PaUtil_GetRingBufferReadAvailable( const PaUtilRingBuffer *rbuf )
+{
+    return ( (rbuf->writeIndex - rbuf->readIndex) & rbuf->bigMask );
+}
+/***************************************************************************
+** Return number of elements available for writing. */
+ring_buffer_size_t PaUtil_GetRingBufferWriteAvailable( const PaUtilRingBuffer *rbuf )
+{
+    return ( rbuf->bufferSize - PaUtil_GetRingBufferReadAvailable(rbuf));
+}
+
+/***************************************************************************
+** Clear buffer. Should only be called when buffer is NOT being read or written. */
+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.
+*/
+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 )
+{
+    ring_buffer_size_t   index;
+    ring_buffer_size_t   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. */
+        ring_buffer_size_t   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;
+    }
+
+    if( available )
+        PaUtil_FullMemoryBarrier(); /* (write-after-read) => full barrier */
+
+    return elementCount;
+}
+
+
+/***************************************************************************
+*/
+ring_buffer_size_t PaUtil_AdvanceRingBufferWriteIndex( PaUtilRingBuffer *rbuf, ring_buffer_size_t elementCount )
+{
+    /* ensure that previous writes are seen before we update the write index 
+       (write after write)
+    */
+    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 read or elementCount, whichever is smaller.
+*/
+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 )
+{
+    ring_buffer_size_t   index;
+    ring_buffer_size_t   available = PaUtil_GetRingBufferReadAvailable( rbuf ); /* doesn't use memory barrier */
+    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. */
+        ring_buffer_size_t 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;
+    }
+    
+    if( available )
+        PaUtil_ReadMemoryBarrier(); /* (read-after-read) => read barrier */
+
+    return elementCount;
+}
+/***************************************************************************
+*/
+ring_buffer_size_t PaUtil_AdvanceRingBufferReadIndex( PaUtilRingBuffer *rbuf, ring_buffer_size_t elementCount )
+{
+    /* ensure that previous reads (copies out of the ring buffer) are always completed before updating (writing) the read index. 
+       (write-after-read) => full barrier
+    */
+    PaUtil_FullMemoryBarrier();
+    return rbuf->readIndex = (rbuf->readIndex + elementCount) & rbuf->bigMask;
+}
+
+/***************************************************************************
+** Return elements written. */
+ring_buffer_size_t PaUtil_WriteRingBuffer( PaUtilRingBuffer *rbuf, const void *data, ring_buffer_size_t elementCount )
+{
+    ring_buffer_size_t 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. */
+ring_buffer_size_t PaUtil_ReadRingBuffer( PaUtilRingBuffer *rbuf, void *data, ring_buffer_size_t elementCount )
+{
+    ring_buffer_size_t 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;
+}
diff --git a/external/pa_ringbuffer.h b/external/pa_ringbuffer.h
new file mode 100644
index 0000000..9edba0d
--- /dev/null
+++ b/external/pa_ringbuffer.h
@@ -0,0 +1,236 @@
+#ifndef PA_RINGBUFFER_H
+#define PA_RINGBUFFER_H
+/*
+ * $Id$
+ * 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.
+*/
+
+#if defined(__APPLE__)
+#include <sys/types.h>
+typedef int32_t ring_buffer_size_t;
+#elif defined( __GNUC__ )
+typedef long ring_buffer_size_t;
+#elif (_MSC_VER >= 1400)
+typedef long ring_buffer_size_t;
+#elif defined(_MSC_VER) || defined(__BORLANDC__)
+typedef long ring_buffer_size_t;
+#else
+typedef long ring_buffer_size_t;
+#endif
+
+
+
+#ifdef __cplusplus
+extern "C"
+{
+#endif /* __cplusplus */
+
+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 );
+
+#ifdef __cplusplus
+}
+#endif /* __cplusplus */
+#endif /* PA_RINGBUFFER_H */