/* * $Id: ringbuffer.c,v 1.1.1.1 2002-07-29 17:06:17 ggeiger Exp $ * ringbuffer.c * Ring Buffer utility.. * * Author: Phil Burk, http://www.softsynth.com * * This program uses the PortAudio Portable Audio Library. * For more information see: http://www.audiomulch.com/portaudio/ * 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. * * 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. * * 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. * */ #include #include #include #include "ringbuffer.h" #include /*************************************************************************** * Initialize FIFO. * numBytes must be power of 2, returns -1 if not. */ long RingBuffer_Init( RingBuffer *rbuf, long numBytes, void *dataPtr ) { if( ((numBytes-1) & numBytes) != 0) return -1; /* Not Power of two. */ rbuf->bufferSize = numBytes; rbuf->buffer = (char *)dataPtr; RingBuffer_Flush( rbuf ); rbuf->bigMask = (numBytes*2)-1; rbuf->smallMask = (numBytes)-1; return 0; } /*************************************************************************** ** Return number of bytes available for reading. */ long RingBuffer_GetReadAvailable( RingBuffer *rbuf ) { return ( (rbuf->writeIndex - rbuf->readIndex) & rbuf->bigMask ); } /*************************************************************************** ** Return number of bytes available for writing. */ long RingBuffer_GetWriteAvailable( RingBuffer *rbuf ) { return ( rbuf->bufferSize - RingBuffer_GetReadAvailable(rbuf)); } /*************************************************************************** ** Clear buffer. Should only be called when buffer is NOT being read. */ void RingBuffer_Flush( RingBuffer *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 RingBuffer_GetWriteRegions( RingBuffer *rbuf, long numBytes, void **dataPtr1, long *sizePtr1, void **dataPtr2, long *sizePtr2 ) { long index; long available = RingBuffer_GetWriteAvailable( 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 RingBuffer_AdvanceWriteIndex( RingBuffer *rbuf, long numBytes ) { 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 RingBuffer_GetReadRegions( RingBuffer *rbuf, long numBytes, void **dataPtr1, long *sizePtr1, void **dataPtr2, long *sizePtr2 ) { long index; long available = RingBuffer_GetReadAvailable( 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 RingBuffer_AdvanceReadIndex( RingBuffer *rbuf, long numBytes ) { return rbuf->readIndex = (rbuf->readIndex + numBytes) & rbuf->bigMask; } /*************************************************************************** ** Return bytes written. */ long RingBuffer_Write( RingBuffer *rbuf, void *data, long numBytes ) { long size1, size2, numWritten; void *data1, *data2; numWritten = RingBuffer_GetWriteRegions( 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 ); } RingBuffer_AdvanceWriteIndex( rbuf, numWritten ); return numWritten; } /*************************************************************************** ** Return bytes read. */ long RingBuffer_Read( RingBuffer *rbuf, void *data, long numBytes ) { long size1, size2, numRead; void *data1, *data2; numRead = RingBuffer_GetReadRegions( 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 ); } RingBuffer_AdvanceReadIndex( rbuf, numRead ); return numRead; }