/* * $Id: pa_ringbuffer.c,v 1.4 2008-01-16 21:54:09 millerpuckette Exp $ * 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 * 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 #include #include #include "pa_ringbuffer.h" #include /**************** * First, we'll define 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 /* 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 */ # elif 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 #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 /*************************************************************************** * Initialize FIFO. * numBytes must be power of 2, returns -1 if not. */ long PaUtil_InitializeRingBuffer( PaUtilRingBuffer *rbuf, long numBytes, void *dataPtr ) { if( ((numBytes-1) & numBytes) != 0) return -1; /* Not Power of two. */ rbuf->bufferSize = numBytes; rbuf->buffer = (char *)dataPtr; PaUtil_FlushRingBuffer( rbuf ); rbuf->bigMask = (numBytes*2)-1; rbuf->smallMask = (numBytes)-1; return 0; } /*************************************************************************** ** Return number of bytes available for reading. */ long PaUtil_GetRingBufferReadAvailable( PaUtilRingBuffer *rbuf ) { PaUtil_ReadMemoryBarrier(); return ( (rbuf->writeIndex - rbuf->readIndex) & rbuf->bigMask ); } /*************************************************************************** ** Return number of bytes available for writing. */ long PaUtil_GetRingBufferWriteAvailable( PaUtilRingBuffer *rbuf ) { /* Since we are calling PaUtil_GetRingBufferReadAvailable, we don't need an aditional MB */ return ( rbuf->bufferSize - PaUtil_GetRingBufferReadAvailable(rbuf)); } /*************************************************************************** ** Clear buffer. Should only be called when buffer is NOT being read. */ 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 numBytes, whichever is smaller. */ long PaUtil_GetRingBufferWriteRegions( PaUtilRingBuffer *rbuf, long numBytes, void **dataPtr1, long *sizePtr1, void **dataPtr2, long *sizePtr2 ) { long index; long available = PaUtil_GetRingBufferWriteAvailable( rbuf ); if( numBytes > available ) numBytes = available; /* Check to see if write is not contiguous. */ index = rbuf->writeIndex & rbuf->smallMask; if( (index + numBytes) > rbuf->bufferSize ) { /* Write data in two blocks that wrap the buffer. */ long firstHalf = rbuf->bufferSize - index; *dataPtr1 = &rbuf->buffer[index]; *sizePtr1 = firstHalf; *dataPtr2 = &rbuf->buffer[0]; *sizePtr2 = numBytes - firstHalf; } else { *dataPtr1 = &rbuf->buffer[index]; *sizePtr1 = numBytes; *dataPtr2 = NULL; *sizePtr2 = 0; } return numBytes; } /*************************************************************************** */ long PaUtil_AdvanceRingBufferWriteIndex( PaUtilRingBuffer *rbuf, long numBytes ) { /* we need to ensure that previous writes are seen before we update the write index */ PaUtil_WriteMemoryBarrier(); return rbuf->writeIndex = (rbuf->writeIndex + numBytes) & 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 written or numBytes, whichever is smaller. */ long PaUtil_GetRingBufferReadRegions( PaUtilRingBuffer *rbuf, long numBytes, void **dataPtr1, long *sizePtr1, void **dataPtr2, long *sizePtr2 ) { long index; long available = PaUtil_GetRingBufferReadAvailable( rbuf ); if( numBytes > available ) numBytes = available; /* Check to see if read is not contiguous. */ index = rbuf->readIndex & rbuf->smallMask; if( (index + numBytes) > rbuf->bufferSize ) { /* Write data in two blocks that wrap the buffer. */ long firstHalf = rbuf->bufferSize - index; *dataPtr1 = &rbuf->buffer[index]; *sizePtr1 = firstHalf; *dataPtr2 = &rbuf->buffer[0]; *sizePtr2 = numBytes - firstHalf; } else { *dataPtr1 = &rbuf->buffer[index]; *sizePtr1 = numBytes; *dataPtr2 = NULL; *sizePtr2 = 0; } return numBytes; } /*************************************************************************** */ long PaUtil_AdvanceRingBufferReadIndex( PaUtilRingBuffer *rbuf, long numBytes ) { /* we need to ensure that previous writes are always seen before updating the index. */ PaUtil_WriteMemoryBarrier(); return rbuf->readIndex = (rbuf->readIndex + numBytes) & rbuf->bigMask; } /*************************************************************************** ** Return bytes written. */ long PaUtil_WriteRingBuffer( PaUtilRingBuffer *rbuf, const void *data, long numBytes ) { long size1, size2, numWritten; void *data1, *data2; numWritten = PaUtil_GetRingBufferWriteRegions( rbuf, numBytes, &data1, &size1, &data2, &size2 ); if( size2 > 0 ) { memcpy( data1, data, size1 ); data = ((char *)data) + size1; memcpy( data2, data, size2 ); } else { memcpy( data1, data, size1 ); } PaUtil_AdvanceRingBufferWriteIndex( rbuf, numWritten ); return numWritten; } /*************************************************************************** ** Return bytes read. */ long PaUtil_ReadRingBuffer( PaUtilRingBuffer *rbuf, void *data, long numBytes ) { long size1, size2, numRead; void *data1, *data2; numRead = PaUtil_GetRingBufferReadRegions( rbuf, numBytes, &data1, &size1, &data2, &size2 ); if( size2 > 0 ) { memcpy( data, data1, size1 ); data = ((char *)data) + size1; memcpy( data, data2, size2 ); } else { memcpy( data, data1, size1 ); } PaUtil_AdvanceRingBufferReadIndex( rbuf, numRead ); return numRead; }