/// <summary>
/// Caluclate the offset in bytes between two data elements.
/// </summary>
/// <param name="from"></param>
/// <param name="to"></param>
/// <returns>Returns the offset in bits between two elements. Return can be negative.</returns>
protected long calculateOffset(DataElement from, DataElement to)
{
DataElementContainer commonAncestor = null;
long fromPosition = 0;
long toPosition = 0;
if (isRelativeOffset)
{
if (!string.IsNullOrEmpty(relativeTo))
{
DataElement relative = from.find(relativeTo);
if (relative == null)
{
throw new PeachException(string.Format("Error, offset relation from element '{0}' couldn't locate relative to element '{1}'.", from.fullName, relativeTo));
}
from = relative;
}
commonAncestor = findCommonRoot(from, to);
if (commonAncestor == null)
{
throw new PeachException("Error, unable to calculate offset between '" +
from.fullName + "' and '" + to.fullName + "'.");
}
BitStream stream = commonAncestor.Value;
if (from != commonAncestor)
{
if (!stream.HasDataElement(from.fullName))
{
throw new PeachException("Error, unable to calculate offset between '" +
from.fullName + "' and '" + to.fullName + "'.");
}
fromPosition = stream.DataElementPosition(from);
}
if (!stream.HasDataElement(to.fullName))
{
throw new PeachException("Error, unable to calculate offset between '" +
from.fullName + "' and '" + to.fullName + "'.");
}
toPosition = stream.DataElementPosition(to);
}
else
{
commonAncestor = findCommonRoot(from, to);
if (commonAncestor == null)
{
throw new PeachException("Error, unable to calculate offset between '" +
from.fullName + "' and '" + to.fullName + "'.");
}
BitStream stream = commonAncestor.Value;
fromPosition = 0;
if (!stream.HasDataElement(to.fullName))
{
throw new PeachException("Error, unable to calculate offset between '" +
from.fullName + "' and '" + to.fullName + "'.");
}
toPosition = stream.DataElementPosition(to);
}
return(toPosition - fromPosition);
}
