Abstract: A computer system includes a processor and a computer readable medium storing a computer program product for encoding a serial bit stream of digital data. The product includes instructions for causing the processor to place a first number of bits from the input bit stream into bit positions of an encoded output unit in accordance with a first value, the first number of bits aligned to a bit position in the encoded output unit in accordance with a second value and insert bits of arbitrary value into remaining, bit positions of the unit of the encoded output unit. In addition, the computer program product includes instructions that cause a processor to select significant bits from a unit of the encoded bit stream in accordance with the first value and the second value to place the selected bits in a decoded bit stream.