bitbuf.cpp #1

//========= Copyright  1996-2005, Valve Corporation, All rights reserved. ============//
//
// Purpose: 
//
// $NoKeywords: $
//
//=============================================================================//

#include "bitbuf.h"
#include "coordsize.h"
#include "vector.h"
#include "mathlib.h"
#include "vstdlib/strtools.h"


// FIXME: Can't use this until we get multithreaded allocations in tier0 working for tools
// This is used by VVIS and fails to link
// NOTE: This must be the last file included!!!
//#include "tier0/memdbgon.h"

#ifdef _XBOX
// mandatory ... wary of above comment and isolating, tier0 is built as MT though
#include "tier0/memdbgon.h"
#endif

static BitBufErrorHandler g_BitBufErrorHandler = 0;


void InternalBitBufErrorHandler( BitBufErrorType errorType, const char *pDebugName )
{
	if ( g_BitBufErrorHandler )
		g_BitBufErrorHandler( errorType, pDebugName );
}


void SetBitBufErrorHandler( BitBufErrorHandler fn )
{
	g_BitBufErrorHandler = fn;
}


// #define BB_PROFILING


// Precalculated bit masks for WriteUBitLong. Using these tables instead of 
// doing the calculations gives a 33% speedup in WriteUBitLong.
unsigned long g_BitWriteMasks[32][33];

// (1 << i) - 1
unsigned long g_ExtraMasks[32];

class CBitWriteMasksInit
{
public:
	CBitWriteMasksInit()
	{
		for( unsigned int startbit=0; startbit < 32; startbit++ )
		{
			for( unsigned int nBitsLeft=0; nBitsLeft < 33; nBitsLeft++ )
			{
				unsigned int endbit = startbit + nBitsLeft;
				g_BitWriteMasks[startbit][nBitsLeft] = (1 << startbit) - 1;
				if(endbit < 32)
					g_BitWriteMasks[startbit][nBitsLeft] |= ~((1 << endbit) - 1);
			}
		}

		for ( unsigned int maskBit=0; maskBit < 32; maskBit++ )
			g_ExtraMasks[maskBit] = (1 << maskBit) - 1;
	}
};
CBitWriteMasksInit g_BitWriteMasksInit;


// ---------------------------------------------------------------------------------------- //
// bf_write
// ---------------------------------------------------------------------------------------- //

bf_write::bf_write()
{
	m_pData = NULL;
	m_nDataBytes = 0;
	m_nDataBits = -1; // set to -1 so we generate overflow on any operation
	m_iCurBit = 0;
	m_bOverflow = false;
	m_bAssertOnOverflow = true;
	m_pDebugName = NULL;
}

bf_write::bf_write( const char *pDebugName, void *pData, int nBytes, int nBits )
{
	m_bAssertOnOverflow = true;
	m_pDebugName = pDebugName;
	StartWriting( pData, nBytes, 0, nBits );
}

bf_write::bf_write( void *pData, int nBytes, int nBits )
{
	m_bAssertOnOverflow = true;
	StartWriting( pData, nBytes, 0, nBits );
}

void bf_write::StartWriting( void *pData, int nBytes, int iStartBit, int nBits )
{
	// Make sure it's dword aligned and padded.
	Assert( (nBytes % 4) == 0 );
	Assert(((unsigned long)pData & 3) == 0);

	m_pData = (unsigned char*)pData;
	m_nDataBytes = nBytes;

	if ( nBits == -1 )
	{
		m_nDataBits = nBytes << 3;
	}
	else
	{
		Assert( nBits <= nBytes*8 );
		m_nDataBits = nBits;
	}

	m_iCurBit = iStartBit;
	m_bOverflow = false;
}

void bf_write::Reset()
{
	m_iCurBit = 0;
	m_bOverflow = false;
}


void bf_write::SetAssertOnOverflow( bool bAssert )
{
	m_bAssertOnOverflow = bAssert;
}


const char* bf_write::GetDebugName()
{
	return m_pDebugName;
}


void bf_write::SetDebugName( const char *pDebugName )
{
	m_pDebugName = pDebugName;
}


void bf_write::SeekToBit( int bitPos )
{
	m_iCurBit = bitPos;
}


// Sign bit comes first
void bf_write::WriteSBitLong( int data, int numbits )
{
	// Do we have a valid # of bits to encode with?
	Assert( numbits >= 1 );

	// Note: it does this wierdness here so it's bit-compatible with regular integer data in the buffer.
	// (Some old code writes direct integers right into the buffer).
	if(data < 0)
	{
#ifdef _DEBUG
	if( numbits < 32 )
	{
		// Make sure it doesn't overflow.

		if( data < 0 )
		{
			Assert( data >= -(1 << (numbits-1)) );
		}
		else
		{
			Assert( data < (1 << (numbits-1)) );
		}
	}
#endif

		WriteUBitLong( (unsigned int)(0x80000000 + data), numbits - 1, false );
		WriteOneBit( 1 );
	}
	else
	{
		WriteUBitLong((unsigned int)data, numbits - 1);
		WriteOneBit( 0 );
	}
}

// writes an unsigned integer with variable bit length
void bf_write::WriteUBitVar( unsigned int data )
{
	unsigned int bits = 0;
	unsigned int base = 0;

	while (data > (base<<1))
	{
		bits++;
		base = (1<<bits)-1;
	}

	// how many bits do we use
	if ( bits > 0)
		WriteUBitLong( 0, bits );

	// end marker
	WriteOneBit( 1 );  

	// write the value
	if ( bits > 0)
		WriteUBitLong( data - base , bits );
}

void bf_write::WriteBitLong(unsigned int data, int numbits, bool bSigned)
{
	if(bSigned)
		WriteSBitLong((int)data, numbits);
	else
		WriteUBitLong(data, numbits);
}

bool bf_write::WriteBits(const void *pInData, int nBits)
{
#if defined( BB_PROFILING )
	VPROF( "bf_write::WriteBits" );
#endif

	unsigned char *pOut = (unsigned char*)pInData;
	int nBitsLeft = nBits;

	if((m_iCurBit+nBits) > m_nDataBits)
	{
		SetOverflowFlag();
		CallErrorHandler( BITBUFERROR_BUFFER_OVERRUN, GetDebugName() );
		return false;
	}

	// Get output dword-aligned.
	while(((unsigned long)pOut & 3) != 0 && nBitsLeft >= 8)
	{

		WriteUBitLong( *pOut, 8, false );
		++pOut;
		nBitsLeft -= 8;
	}
	
	// check if we can use fast memcpy if m_iCurBit is byte aligned
	if ( (nBitsLeft >= 32) && (m_iCurBit & 7) == 0 )
	{
		int numbytes = (nBitsLeft >> 3); 
		int numbits = numbytes << 3;
		
		// Bounds checking..
		// TODO: May not need this check anymore
		if((m_iCurBit+numbits) > m_nDataBits)
		{
			m_iCurBit = m_nDataBits;
			SetOverflowFlag();
			CallErrorHandler( BITBUFERROR_BUFFER_OVERRUN, GetDebugName() );
			return false;
		}
		
		Q_memcpy( m_pData+(m_iCurBit>>3), pOut, numbytes );
		pOut += numbytes;
		nBitsLeft -= numbits;
		m_iCurBit += numbits;
	}

	// Read dwords.
	while(nBitsLeft >= 32)
	{
		WriteUBitLong( *((unsigned long*)pOut), 32, false );
		pOut += sizeof(unsigned long);
		nBitsLeft -= 32;
	}

	// Read the remaining bytes.
	while(nBitsLeft >= 8)
	{
		WriteUBitLong( *pOut, 8, false );
		++pOut;
		nBitsLeft -= 8;
	}
	
	// Read the remaining bits.
	if(nBitsLeft)
	{
		WriteUBitLong( *pOut, nBitsLeft, false );
	}

	return !IsOverflowed();
}


bool bf_write::WriteBitsFromBuffer( bf_read *pIn, int nBits )
{
	// This could be optimized a little by
	while ( nBits > 32 )
	{
		WriteUBitLong( pIn->ReadUBitLong( 32 ), 32 );
		nBits -= 32;
	}

	WriteUBitLong( pIn->ReadUBitLong( nBits ), nBits );
	return !IsOverflowed() && !pIn->IsOverflowed();
}


void bf_write::WriteBitAngle( float fAngle, int numbits )
{
	int d;
	unsigned int mask;
	unsigned int shift;

	shift = (1<<numbits);
	mask = shift - 1;

	d = (int)( (fAngle / 360.0) * shift );
	d &= mask;

	WriteUBitLong((unsigned int)d, numbits);
}

void bf_write::WriteBitCoord (const float f)
{
#if defined( BB_PROFILING )
	VPROF( "bf_write::WriteBitCoord" );
#endif
	int		signbit = (f <= -COORD_RESOLUTION);
	int		intval = (int)abs(f);
	int		fractval = abs((int)(f*COORD_DENOMINATOR)) & (COORD_DENOMINATOR-1);


	// Send the bit flags that indicate whether we have an integer part and/or a fraction part.
	WriteOneBit( intval );
	WriteOneBit( fractval );

	if ( intval || fractval )
	{
		// Send the sign bit
		WriteOneBit( signbit );

		// Send the integer if we have one.
		if ( intval )
		{
			// Adjust the integers from [1..MAX_COORD_VALUE] to [0..MAX_COORD_VALUE-1]
			intval--;
			WriteUBitLong( (unsigned int)intval, COORD_INTEGER_BITS );
		}
		
		// Send the fraction if we have one
		if ( fractval )
		{
			WriteUBitLong( (unsigned int)fractval, COORD_FRACTIONAL_BITS );
		}
	}
}

void bf_write::WriteBitFloat(float val)
{
	long intVal;

	Assert(sizeof(long) == sizeof(float));
	Assert(sizeof(float) == 4);

	intVal = *((long*)&val);
	WriteUBitLong( intVal, 32 );
}

void bf_write::WriteBitVec3Coord( const Vector& fa )
{
	int		xflag, yflag, zflag;

	xflag = (fa[0] >= COORD_RESOLUTION) || (fa[0] <= -COORD_RESOLUTION);
	yflag = (fa[1] >= COORD_RESOLUTION) || (fa[1] <= -COORD_RESOLUTION);
	zflag = (fa[2] >= COORD_RESOLUTION) || (fa[2] <= -COORD_RESOLUTION);

	WriteOneBit( xflag );
	WriteOneBit( yflag );
	WriteOneBit( zflag );

	if ( xflag )
		WriteBitCoord( fa[0] );
	if ( yflag )
		WriteBitCoord( fa[1] );
	if ( zflag )
		WriteBitCoord( fa[2] );
}

void bf_write::WriteBitNormal( float f )
{
	int	signbit = (f <= -NORMAL_RESOLUTION);

	// NOTE: Since +/-1 are valid values for a normal, I'm going to encode that as all ones
	unsigned int fractval = abs( (int)(f*NORMAL_DENOMINATOR) );

	// clamp..
	if (fractval > NORMAL_DENOMINATOR)
		fractval = NORMAL_DENOMINATOR;

	// Send the sign bit
	WriteOneBit( signbit );

	// Send the fractional component
	WriteUBitLong( fractval, NORMAL_FRACTIONAL_BITS );
}

void bf_write::WriteBitVec3Normal( const Vector& fa )
{
	int		xflag, yflag;

	xflag = (fa[0] >= NORMAL_RESOLUTION) || (fa[0] <= -NORMAL_RESOLUTION);
	yflag = (fa[1] >= NORMAL_RESOLUTION) || (fa[1] <= -NORMAL_RESOLUTION);

	WriteOneBit( xflag );
	WriteOneBit( yflag );

	if ( xflag )
		WriteBitNormal( fa[0] );
	if ( yflag )
		WriteBitNormal( fa[1] );
	
	// Write z sign bit
	int	signbit = (fa[2] <= -NORMAL_RESOLUTION);
	WriteOneBit( signbit );
}

void bf_write::WriteBitAngles( const QAngle& fa )
{
	// FIXME:
	Vector tmp( fa.x, fa.y, fa.z );
	WriteBitVec3Coord( tmp );
}

void bf_write::WriteChar(int val)
{
	WriteSBitLong(val, sizeof(char) << 3);
}

void bf_write::WriteByte(int val)
{
	WriteUBitLong(val, sizeof(unsigned char) << 3);
}

void bf_write::WriteShort(int val)
{
	WriteSBitLong(val, sizeof(short) << 3);
}

void bf_write::WriteWord(int val)
{
	WriteUBitLong(val, sizeof(unsigned short) << 3);
}

void bf_write::WriteLong(long val)
{
	WriteSBitLong(val, sizeof(long) << 3);
}

void bf_write::WriteFloat(float val)
{
	WriteBits(&val, sizeof(val) << 3);
}

bool bf_write::WriteBytes( const void *pBuf, int nBytes )
{
	return WriteBits(pBuf, nBytes << 3);
}

bool bf_write::WriteString(const char *pStr)
{
	if(pStr)
	{
		do
		{
			WriteChar( *pStr );
			++pStr;
		} while( *(pStr-1) != 0 );
	}
	else
	{
		WriteChar( 0 );
	}

	return !IsOverflowed();
}

// ---------------------------------------------------------------------------------------- //
// bf_read
// ---------------------------------------------------------------------------------------- //

bf_read::bf_read()
{
	m_pData = NULL;
	m_nDataBytes = 0;
	m_nDataBits = -1; // set to -1 so we overflow on any operation
	m_iCurBit = 0;
	m_bOverflow = false;
	m_bAssertOnOverflow = true;
	m_pDebugName = NULL;
}

bf_read::bf_read( const void *pData, int nBytes, int nBits )
{
	m_bAssertOnOverflow = true;
	StartReading( pData, nBytes, 0, nBits );
}

bf_read::bf_read( const char *pDebugName, const void *pData, int nBytes, int nBits )
{
	m_bAssertOnOverflow = true;
	m_pDebugName = pDebugName;
	StartReading( pData, nBytes, 0, nBits );
}

void bf_read::StartReading( const void *pData, int nBytes, int iStartBit, int nBits )
{
	// Make sure we're dword aligned.
	Assert(((unsigned long)pData & 3) == 0);

	m_pData = (unsigned char*)pData;
	m_nDataBytes = nBytes;

	if ( nBits == -1 )
	{
		m_nDataBits = m_nDataBytes << 3;
	}
	else
	{
		Assert( nBits <= nBytes*8 );
		m_nDataBits = nBits;
	}

	m_iCurBit = iStartBit;
	m_bOverflow = false;
}

void bf_read::Reset()
{
	m_iCurBit = 0;
	m_bOverflow = false;
}

void bf_read::SetAssertOnOverflow( bool bAssert )
{
	m_bAssertOnOverflow = bAssert;
}

const char* bf_read::GetDebugName()
{
	return m_pDebugName;
}

void bf_read::SetDebugName( const char *pName )
{
	m_pDebugName = pName;
}

unsigned int bf_read::CheckReadUBitLong(int numbits)
{
	// Ok, just read bits out.
	int i, nBitValue;
	unsigned int r = 0;

	for(i=0; i < numbits; i++)
	{
		nBitValue = ReadOneBitNoCheck();
		r |= nBitValue << i;
	}
	m_iCurBit -= numbits;
	
	return r;
}

bool bf_read::ReadBits(void *pOutData, int nBits)
{
#if defined( BB_PROFILING )
	VPROF( "bf_write::ReadBits" );
#endif

	unsigned char *pOut = (unsigned char*)pOutData;
	int nBitsLeft = nBits;

	
	// Get output dword-aligned.
	while(((unsigned long)pOut & 3) != 0 && nBitsLeft >= 8)
	{
		*pOut = (unsigned char)ReadUBitLong(8);
		++pOut;
		nBitsLeft -= 8;
	}

	// Read dwords.
	while(nBitsLeft >= 32)
	{
		*((unsigned long*)pOut) = ReadUBitLong(32);
		pOut += sizeof(unsigned long);
		nBitsLeft -= 32;
	}

	// Read the remaining bytes.
	while(nBitsLeft >= 8)
	{
		*pOut = ReadUBitLong(8);
		++pOut;
		nBitsLeft -= 8;
	}
	
	// Read the remaining bits.
	if(nBitsLeft)
	{
		*pOut = ReadUBitLong(nBitsLeft);
	}

	return !IsOverflowed();
}

float bf_read::ReadBitAngle( int numbits )
{
	float fReturn;
	int i;
	float shift;

	shift = (float)( 1 << numbits );

	i = ReadUBitLong( numbits );
	fReturn = (float)i * (360.0 / shift);

	return fReturn;
}

unsigned int bf_read::PeekUBitLong( int numbits )
{
	unsigned int r;
	int i, nBitValue;
#ifdef BIT_VERBOSE
	int nShifts = numbits;
#endif

	bf_read savebf;

	savebf = *this;  // Save current state info

	r = 0;
	for(i=0; i < numbits; i++)
	{
		nBitValue = ReadOneBit();

		// Append to current stream
		if ( nBitValue )
		{
			r |= 1 << i;
		}
	}
	
	*this = savebf;

#ifdef BIT_VERBOSE
	Con_Printf( "PeekBitLong:  %i %i\n", nShifts, (unsigned int)r );
#endif

	return r;
}

// Append numbits least significant bits from data to the current bit stream
int bf_read::ReadSBitLong( int numbits )
{
	int r, sign;

	r = ReadUBitLong(numbits - 1);

	// Note: it does this wierdness here so it's bit-compatible with regular integer data in the buffer.
	// (Some old code writes direct integers right into the buffer).
	sign = ReadOneBit();
	if(sign)
		r = -((1 << (numbits-1)) - r);

	return r;
}

unsigned int bf_read::ReadUBitVar()
{
	int bits = 0; // how many bits are used to encode delta offset

		// how many bits do we use
	while ( ReadOneBit() == 0 )
		bits++;

	unsigned int data = (1<<bits)-1;
	
	// read the value
	if ( bits > 0)
		data += ReadUBitLong( bits );

	return data;
}


unsigned int bf_read::ReadBitLong(int numbits, bool bSigned)
{
	if(bSigned)
		return (unsigned int)ReadSBitLong(numbits);
	else
		return ReadUBitLong(numbits);
}


// Basic Coordinate Routines (these contain bit-field size AND fixed point scaling constants)
float bf_read::ReadBitCoord (void)
{
#if defined( BB_PROFILING )
	VPROF( "bf_write::ReadBitCoord" );
#endif
	int		intval=0,fractval=0,signbit=0;
	float	value = 0.0;


	// Read the required integer and fraction flags
	intval = ReadOneBit();
	fractval = ReadOneBit();

	// If we got either parse them, otherwise it's a zero.
	if ( intval || fractval )
	{
		// Read the sign bit
		signbit = ReadOneBit();

		// If there's an integer, read it in
		if ( intval )
		{
			// Adjust the integers from [0..MAX_COORD_VALUE-1] to [1..MAX_COORD_VALUE]
			intval = ReadUBitLong( COORD_INTEGER_BITS ) + 1;
		}

		// If there's a fraction, read it in
		if ( fractval )
		{
			fractval = ReadUBitLong( COORD_FRACTIONAL_BITS );
		}

		// Calculate the correct floating point value
		value = intval + ((float)fractval * COORD_RESOLUTION);

		// Fixup the sign if negative.
		if ( signbit )
			value = -value;
	}

	return value;
}

void bf_read::ReadBitVec3Coord( Vector& fa )
{
	int		xflag, yflag, zflag;

	// This vector must be initialized! Otherwise, If any of the flags aren't set, 
	// the corresponding component will not be read and will be stack garbage.
	fa.Init( 0, 0, 0 );

	xflag = ReadOneBit();
	yflag = ReadOneBit(); 
	zflag = ReadOneBit();

	if ( xflag )
		fa[0] = ReadBitCoord();
	if ( yflag )
		fa[1] = ReadBitCoord();
	if ( zflag )
		fa[2] = ReadBitCoord();
}

float bf_read::ReadBitNormal (void)
{
	// Read the sign bit
	int	signbit = ReadOneBit();

	// Read the fractional part
	unsigned int fractval = ReadUBitLong( NORMAL_FRACTIONAL_BITS );

	// Calculate the correct floating point value
	float value = (float)fractval * NORMAL_RESOLUTION;

	// Fixup the sign if negative.
	if ( signbit )
		value = -value;

	return value;
}

void bf_read::ReadBitVec3Normal( Vector& fa )
{
	int xflag = ReadOneBit();
	int yflag = ReadOneBit(); 

	if (xflag)
		fa[0] = ReadBitNormal();
	else
		fa[0] = 0.0f;

	if (yflag)
		fa[1] = ReadBitNormal();
	else
		fa[1] = 0.0f;

	// The first two imply the third (but not its sign)
	int znegative = ReadOneBit();

	float fafafbfb = fa[0] * fa[0] + fa[1] * fa[1];
	if (fafafbfb < 1.0f)
		fa[2] = sqrt( 1.0f - fafafbfb );
	else
		fa[2] = 0.0f;

	if (znegative)
		fa[2] = -fa[2];
}

void bf_read::ReadBitAngles( QAngle& fa )
{
	Vector tmp;
	ReadBitVec3Coord( tmp );
	fa.Init( tmp.x, tmp.y, tmp.z );
}

int bf_read::ReadChar()
{
	return ReadSBitLong(sizeof(char) << 3);
}

int bf_read::ReadByte()
{
	return ReadUBitLong(sizeof(unsigned char) << 3);
}

int bf_read::ReadShort()
{
	return ReadSBitLong(sizeof(short) << 3);
}

int bf_read::ReadWord()
{
	return ReadUBitLong(sizeof(unsigned short) << 3);
}

long bf_read::ReadLong()
{
	return ReadSBitLong(sizeof(long) << 3);
}

float bf_read::ReadFloat()
{
	float ret;
	Assert( sizeof(ret) == 4 );
	ReadBits(&ret, 32);
	return ret;
}

bool bf_read::ReadBytes(void *pOut, int nBytes)
{
	return ReadBits(pOut, nBytes << 3);
}

bool bf_read::ReadString( char *pStr, int maxLen, bool bLine, int *pOutNumChars )
{
	Assert( maxLen != 0 );

	bool bTooSmall = false;
	int iChar = 0;
	while(1)
	{
		char val = ReadChar();
		if ( val == 0 )
			break;
		else if ( bLine && val == '\n' )
			break;

		if ( iChar < (maxLen-1) )
		{
			pStr[iChar] = val;
			++iChar;
		}
		else
		{
			bTooSmall = true;
		}
	}

	// Make sure it's null-terminated.
	Assert( iChar < maxLen );
	pStr[iChar] = 0;

	if ( pOutNumChars )
		*pOutNumChars = iChar;

	return !IsOverflowed() && !bTooSmall;
}


char* bf_read::ReadAndAllocateString( bool *pOverflow )
{
	char str[2048];
	
	int nChars;
	bool bOverflow = !ReadString( str, sizeof( str ), false, &nChars );
	if ( pOverflow )
		*pOverflow = bOverflow;

	// Now copy into the output and return it;
	char *pRet = new char[ nChars + 1 ];
	for ( int i=0; i <= nChars; i++ )
		pRet[i] = str[i];

	return pRet;
}

	
bool bf_read::Seek(int iBit)
{
	if(iBit < 0)
	{
		SetOverflowFlag();
		m_iCurBit = m_nDataBits;
		return false;
	}
	else if(iBit > m_nDataBits)
	{
		SetOverflowFlag();
		m_iCurBit = m_nDataBits;
		return false;
	}
	else
	{
		m_iCurBit = iBit;
		return true;
	}
}

void bf_read::ExciseBits( int startbit, int bitstoremove )
{
	int endbit = startbit + bitstoremove;
	int remaining_to_end = m_nDataBits - endbit;

	bf_write temp;
	temp.StartWriting( (void *)m_pData, m_nDataBits << 3, startbit );

	Seek( endbit );

	for ( int i = 0; i < remaining_to_end; i++ )
	{
		temp.WriteOneBit( ReadOneBit() );
	}

	Seek( startbit );
	
	m_nDataBits -= bitstoremove;
	m_nDataBytes = m_nDataBits >> 3;
}