// 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 old_bf_write::WriteUBitVar( unsigned int data )
{
if ( ( data &0xf ) == data )
{
WriteUBitLong( 0, 2 );
WriteUBitLong( data, 4 );
}
else
{
if ( ( data & 0xff ) == data )
{
WriteUBitLong( 1, 2 );
WriteUBitLong( data, 8 );
}
else
{
if ( ( data & 0xfff ) == data )
{
WriteUBitLong( 2, 2 );
WriteUBitLong( data, 12 );
}
else
{
WriteUBitLong( 0x3, 2 );
WriteUBitLong( data, 32 );
}
}
}
#if 0
#if !FAST_BIT_SCAN
unsigned int bits = 0;
unsigned int base = 0;
while (data > (base<<1))
{
bits++;
base = BitForBitnum(bits)-1;
}
#else
unsigned int bits = BitCountNeededToEncode(data);
unsigned int base = GetBitForBitnum(bits)-1;
#endif
// how many bits do we use
WriteUBitLong( 0, bits );
// end marker
WriteOneBit( 1 );
// write the value
if ( bits > 0)
WriteUBitLong( data - base , bits );
#endif
}
// 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 );
}
