private long ComputeMagic(long length, FileEnvelopeId id) { // HashCodeHelper performs a stable hash code computation. // We take into account the other header fields, and the file length. return(HashCodeHelper.Combine( HashCodeHelper.GetOrdinalHashCode64(m_name), HashCodeHelper.GetOrdinalHashCode64(id.Value), Version | (long)(((ulong)(uint)m_version) << 32), length)); }