Method ExtractValue

cpp/src/command_classes/CommandClass.cpp:518–612

----------------------------------------------------------------------------- Read a value from a variable length sequence of bytes -----------------------------------------------------------------------------

// Read a value from a variable length sequence of bytes
//-----------------------------------------------------------------------------
string CommandClass::ExtractValue
(
		uint8 const* _data,
		uint8* _scale,
		uint8* _precision,
		uint8 _valueOffset // = 1
)const
{
	uint8 const size = _data[0] & c_sizeMask;
	uint8 const precision = (_data[0] & c_precisionMask) >> c_precisionShift;

	if( _scale )
	{
		*_scale = (_data[0] & c_scaleMask) >> c_scaleShift;
	}

	if( _precision )
	{
		*_precision = precision;
	}

	uint32 value = 0;
	uint8 i;
	for( i=0; i<size; ++i )
	{
		value <<= 8;
		value |= (uint32)_data[i+(uint32)_valueOffset];
	}

	// Deal with sign extension.  All values are signed
	string res;
	if( _data[_valueOffset] & 0x80 )
	{
		res = "-";

		// MSB is signed
		if( size == 1 )
		{
			value |= 0xffffff00;
		}
		else if( size == 2 )
		{
			value |= 0xffff0000;
		}
	}

	// Convert the integer to a decimal string.  We avoid
	// using floats to prevent accuracy issues.
	char numBuf[12] = {0};

	if( precision == 0 )
	{
		// The precision is zero, so we can just print the number directly into the string.
		snprintf( numBuf, 12, "%d", (signed int)value );
		res = numBuf;
	}
	else
	{