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Diffstat (limited to 'portaudio/src/common/pa_ringbuffer.c')
| -rw-r--r-- | portaudio/src/common/pa_ringbuffer.c | 237 |
1 files changed, 237 insertions, 0 deletions
diff --git a/portaudio/src/common/pa_ringbuffer.c b/portaudio/src/common/pa_ringbuffer.c new file mode 100644 index 0000000..b978d54 --- /dev/null +++ b/portaudio/src/common/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; +} |