Team Fortress 2 Source Code as on 22/4/2020
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//========= Copyright Valve Corporation, All rights reserved. ============//
//
// The copyright to the contents herein is the property of Valve, L.L.C.
// The contents may be used and/or copied only with the written permission of
// Valve, L.L.C., or in accordance with the terms and conditions stipulated in
// the agreement/contract under which the contents have been supplied.
//
//*****************************************************************************
//
// Contents:
//
// CSimpleBitString
//
// Authors: chrisn
//
// Target restrictions:
//
// Tool restrictions:
//
// Things to do:
//
//*****************************************************************************
//*****************************************************************************
//
// Include files required to build and use this module.
//
//*****************************************************************************
// Precompiled header (must come first - includes project common headers)
//#include "stdafx.h"
#include "tier0/platform.h"
#include "tier1/utlvector.h"
#include "simplebitstring.h"
//*****************************************************************************
//
// Class definitions:
//
//*****************************************************************************
//
// class CSimpleBitString::iterator
//
//-----------------------------------------------------------------------------
//
// Function:
//
//-----------------------------------------------------------------------------
void CSimpleBitString::AppendBits( uint64 u64Data, uint32 NumSignificantLowBitsOfData )
{
Assert
(
NumSignificantLowBitsOfData <= 64
);
while ( NumSignificantLowBitsOfData > 0 )
{
// Clear top bits of data
if ( NumSignificantLowBitsOfData < 64 )
u64Data &= ( (1ULL << NumSignificantLowBitsOfData) - 1 ); // will fail for 64 bits
uint32 Idx = m_uNumBits / 8;
uint32 NumUsedBitsInLastByte = m_uNumBits % 8;
uint32 NumAvailableBitsInLastByte = 8 - NumUsedBitsInLastByte;
uint32 NumBitsToPutInThisByte
= min( NumAvailableBitsInLastByte, NumSignificantLowBitsOfData );
uint8 BitsForThisByte
= ( u64Data >> (NumSignificantLowBitsOfData - NumBitsToPutInThisByte) )
& ( (1ULL << NumBitsToPutInThisByte) - 1 );
m_vecU8[Idx] |= ( BitsForThisByte
<< ( NumAvailableBitsInLastByte - NumBitsToPutInThisByte ) );
m_uNumBits += NumBitsToPutInThisByte;
NumAvailableBitsInLastByte -= NumBitsToPutInThisByte;
if ( NumAvailableBitsInLastByte == 0 )
{
m_vecU8[ m_vecU8.AddToTail() ] = 0x00;
}
// We've used the top N bits of data
NumSignificantLowBitsOfData -= NumBitsToPutInThisByte;
}
}
//-----------------------------------------------------------------------------
//
// Function:
//
//-----------------------------------------------------------------------------
void CSimpleBitString::AppendBits( const uint8 * pData, uint32 NumBitsOfData )
{
Assert( pData );
uint32 NumBytes = NumBitsOfData / 8;
for ( uint32 i = 0; i < NumBytes; ++i )
{
AppendBits( *(pData++), 8 );
}
uint32 NumTailBits = NumBitsOfData % 8;
AppendBits( (*pData) >> (8U - NumTailBits), NumTailBits );
}
//-----------------------------------------------------------------------------
//
// Function:
//
//-----------------------------------------------------------------------------
void CSimpleBitString::ReversiblyObfusticateBitsFromStart( uint NumBits, const uint8 * pObfusticationData, size_t uSizeOfObfusticationData )
{
Assert( pObfusticationData );
if ( NumBits > m_uNumBits
|| NumBits > uSizeOfObfusticationData * 8
)
{
AssertMsg( false, "ReversiblyObfusticateBitsFromStart(): Bad NumBits" );
return; // bugbug taylor bool return
}
uint8 * pBits = & m_vecU8[0];
uint NumBytes = NumBits / 8;
for ( uint i = 0; i < NumBytes; ++i )
{
*(pBits++) ^= *(pObfusticationData++);
}
uint NumTailBits = NumBits % 8;
if ( NumTailBits > 0 )
{
*pBits ^= ( *(pObfusticationData++) & (((1U << NumTailBits) - 1) << (8U - NumTailBits) ) );
}
}
//-----------------------------------------------------------------------------
//
// Function:
//
//-----------------------------------------------------------------------------
uint8 CSimpleBitString::GetByteChecksumFromStart( uint NumBits ) const
{
if ( NumBits > m_uNumBits )
{
AssertMsg( false, "GenerateByteChecksumFromStart(): Bad NumBits" );
return 0;
}
uint8 u8Checksum = 0;
const uint8 * pBits = & m_vecU8[0];
uint NumBytes = NumBits / 8;
for ( uint i = 0; i < NumBytes; ++i )
{
u8Checksum += *(pBits++);
}
uint NumTailBits = NumBits % 8;
if ( NumTailBits > 0 )
{
u8Checksum += ( *(pBits) & (((1U << NumTailBits) - 1) << (8U - NumTailBits) ) );
}
return u8Checksum;
}
//
// class CSimpleBitString::iterator
//
uint32 CSimpleBitString::iterator::GetNextBits( uint32 NumBitsToGet )
{
Assert
(
NumBitsToGet <= 32
);
return static_cast<uint32>( GetNextBits64( NumBitsToGet ) );
}
uint64 CSimpleBitString::iterator::GetNextBits64( uint32 NumBitsToGet )
{
Assert
(
NumBitsToGet <= 64
);
if ( m_uNextBitIdx + NumBitsToGet > m_rSimpleBitString.m_uNumBits )
{
AssertMsg( false, "Not enough bits in CSimpleBitString" );
return 0;
}
uint64 u64Data = 0;
while ( NumBitsToGet > 0 )
{
uint32 Idx = m_uNextBitIdx / 8;
Assert( Idx < (uint32)m_rSimpleBitString.m_vecU8.Count() );
uint32 NumConsumedBitsInThisByte = m_uNextBitIdx % 8;
uint32 NumAvailableBitsInThisByte = 8 - NumConsumedBitsInThisByte;
uint32 NumBitsToGetFromThisByte
= min( NumAvailableBitsInThisByte, NumBitsToGet );
uint8 BitsFromThisByte
= ( m_rSimpleBitString.m_vecU8[Idx] >> (NumAvailableBitsInThisByte - NumBitsToGetFromThisByte) )
& ( (1UL << NumBitsToGetFromThisByte) - 1 );
u64Data <<= NumBitsToGetFromThisByte;
u64Data |= BitsFromThisByte;
m_uNextBitIdx += NumBitsToGetFromThisByte;
NumBitsToGet -= NumBitsToGetFromThisByte;
}
return u64Data;
}