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Diffstat (limited to 'engine/audio/private/circularbuffer.cpp')
| -rw-r--r-- | engine/audio/private/circularbuffer.cpp | 271 |
1 files changed, 271 insertions, 0 deletions
diff --git a/engine/audio/private/circularbuffer.cpp b/engine/audio/private/circularbuffer.cpp new file mode 100644 index 0000000..8c188e3 --- /dev/null +++ b/engine/audio/private/circularbuffer.cpp @@ -0,0 +1,271 @@ +//========= Copyright Valve Corporation, All rights reserved. ============// +// +// Purpose: Circular Buffer +// +//=============================================================================// + +#include "tier0/dbg.h" +#include "circularbuffer.h" + +// memdbgon must be the last include file in a .cpp file!!! +#include "tier0/memdbgon.h" + +CCircularBuffer::CCircularBuffer() +{ + SetSize( 0 ); +} + +CCircularBuffer::CCircularBuffer(int size) +{ + SetSize(size); +} + +//------------------ Copyright (c) 1999 Valve, LLC. ---------------------------- +//Purpose : Sets the maximum size for a circular buffer. This does not do any +// memory allocation, it simply informs the buffer of its size. +//Author : DSpeyrer +//------------------------------------------------------------------------------ +void CCircularBuffer::SetSize(int size) +{ + Assert( this ); + + m_nSize = size; + m_nRead = 0; + m_nWrite = 0; + m_nCount = 0; +} + + +//------------------ Copyright (c) 1999 Valve, LLC. ---------------------------- +//Purpose : Empties a circular buffer. +//Author : DSpeyrer +//------------------------------------------------------------------------------ +void CCircularBuffer::Flush() +{ + AssertValid(); + + m_nRead = 0; + m_nWrite = 0; + m_nCount = 0; +} + + +//------------------ Copyright (c) 1999 Valve, LLC. ---------------------------- +//Purpose : Returns the available space in a circular buffer. +//Author : DSpeyrer +//------------------------------------------------------------------------------ +int CCircularBuffer::GetWriteAvailable() +{ + AssertValid(); + + return(m_nSize - m_nCount); +} + + +//------------------ Copyright (c) 1999 Valve, LLC. ---------------------------- +//Purpose : Returns the size of a circular buffer. +//Author : DSpeyrer +//------------------------------------------------------------------------------ +int CCircularBuffer::GetSize() +{ + AssertValid(); + + return(m_nSize); +} + + +//------------------ Copyright (c) 1999 Valve, LLC. ---------------------------- +//Purpose : Returns the number of bytes in a circular buffer. +//Author : DSpeyrer +//------------------------------------------------------------------------------ +int CCircularBuffer::GetReadAvailable() +{ + AssertValid(); + + return(m_nCount); +} + + +//------------------ Copyright (c) 1999 Valve, LLC. ---------------------------- +//Purpose : Reads a specified number of bytes from a circular buffer without +// consuming them. They will still be available for future calls to +// Read or Peek. +//Input : pchDest - destination buffer. +// m_nCount - number of bytes to place in destination buffer. +//Output : Returns the number of bytes placed in the destination buffer. +//Author : DSpeyrer +//------------------------------------------------------------------------------ +int CCircularBuffer::Peek(char *pchDest, int nCount) +{ + // If no data available, just return. + if(m_nCount == 0) + { + return(0); + } + + // + // Requested amount should not exceed the available amount. + // + nCount = MIN(m_nCount, nCount); + + // + // Copy as many of the requested bytes as possible. + // If buffer wrap occurs split the data into two chunks. + // + if (m_nRead + nCount > m_nSize) + { + int nCount1 = m_nSize - m_nRead; + memcpy(pchDest, &m_chData[m_nRead], nCount1); + pchDest += nCount1; + + int nCount2 = nCount - nCount1; + memcpy(pchDest, m_chData, nCount2); + } + // Otherwise copy it in one go. + else + { + memcpy(pchDest, &m_chData[m_nRead], nCount); + } + + AssertValid(); + return nCount; +} + + +//------------------ Copyright (c) 1999 Valve, LLC. ---------------------------- +//Purpose : Advances the read index, consuming a specified number of bytes from +// the circular buffer. +//Input : m_nCount - number of bytes to consume. +//Output : Returns the actual number of bytes consumed. +//Author : DSpeyrer +//------------------------------------------------------------------------------ +int CCircularBuffer::Advance(int nCount) +{ + // If no data available, just return. + if (m_nCount == 0) + { + return(0); + } + + // + // Requested amount should not exceed the available amount. + // + nCount = MIN(m_nCount, nCount); + + // Advance the read pointer, checking for buffer + //wrap. + // + m_nRead = (m_nRead + nCount) % m_nSize; + m_nCount -= nCount; + + // + // If we have emptied the buffer, reset the read and write indices + // to minimize buffer wrap. + // + if (m_nCount == 0) + { + m_nRead = 0; + m_nWrite = 0; + } + + AssertValid(); + return nCount; +} + + +//------------------ Copyright (c) 1999 Valve, LLC. ---------------------------- +//Purpose : Reads a specified number of bytes from a circular buffer. The bytes +// will be consumed by the read process. +//Input : pchDest - destination buffer. +// m_nCount - number of bytes to place in destination buffer. +//Output : Returns the number of bytes placed in the destination buffer. +//Author : DSpeyrer +//------------------------------------------------------------------------------ +int CCircularBuffer::Read(void *pchDestIn, int nCount) +{ + int nPeeked; + int nRead; + + char *pchDest = (char*)pchDestIn; + + nPeeked = Peek(pchDest, nCount); + + if (nPeeked != 0) + { + nRead = Advance(nPeeked); + + assert( nRead == nPeeked); + } + else + { + nRead = 0; + } + + AssertValid(); + return(nRead); +} + + +//------------------ Copyright (c) 1999 Valve, LLC. ---------------------------- +//Purpose : Writes a specified number of bytes to the buffer. +//Input : pm_chData - buffer containing bytes to bw written. +// m_nCount - the number of bytes to write. +//Output : Returns the number of bytes written. If there wa insufficient space +// to write all requested bytes, the value returned will be less than +// the requested amount. +//Author : DSpeyrer +//------------------------------------------------------------------------------ +int CCircularBuffer::Write(void *pData, int nBytesRequested) +{ + // Write all the data. + int nBytesToWrite = nBytesRequested; + char *pDataToWrite = (char*)pData; + + while(nBytesToWrite) + { + int from = m_nWrite; + int to = m_nWrite + nBytesToWrite; + + if(to >= m_nSize) + { + to = m_nSize; + } + + memcpy(&m_chData[from], pDataToWrite, to - from); + pDataToWrite += to - from; + + m_nWrite = to % m_nSize; + nBytesToWrite -= to - from; + } + + // Did it cross the read pointer? Then slide the read pointer up. + // This way, we will discard the old data. + if(nBytesRequested > (m_nSize - m_nCount)) + { + m_nCount = m_nSize; + m_nRead = m_nWrite; + } + else + { + m_nCount += nBytesRequested; + } + + AssertValid(); + return nBytesRequested; +} + +CCircularBuffer *AllocateCircularBuffer( int nSize ) +{ + char *pBuff = (char *)malloc( sizeof( CCircularBuffer ) + nSize - 1 ); + + CCircularBuffer *pCCircularBuffer = (CCircularBuffer *)pBuff; + + pCCircularBuffer->SetSize( nSize ); + return pCCircularBuffer; +} + +void FreeCircularBuffer( CCircularBuffer *pCircularBuffer ) +{ + free( (char*)pCircularBuffer ); +} + |