Embodiments of the present invention provide a fast, software-implemented data scrambling system for data communications. For pseudo-random codes that are periodic within a predetermined number of bits, a memory array may be populated with segments of the code, one entry in the array starting at a unique bit position within the code. During data scrambling, a seed code may be used to identify a first entry from the array that should be used for scrambling. Thereafter, subsequent segments may be retrieved by traversing the array in a regular fashion. By calculating the code before use and by populating the array prior to processing of any source data, the system is very fast.