A METHOD AND AN APPARATUS FOR BIT STUFFING AND A CORRESPONDING METHOD AND APPARATUS FOR BIT DE-STUFFING

摘要

A method for bit stuffing a data stream, in which data is read from an input buffer, the data is bit stuffed and stored in an output buffer. One byte for evaluation is collected from the input buffer at a time. This byte is divided into two 4-bit groups Msb4 and Lsb4. The two 4-bit groups are evaluated together to decide if the bits must be bit stuffed or not. The evaluation is based upon counting the number of consecutive ones in the two 4-bit groups. Msb4 is the four most significant bits and the number of ones is counted by starting with the least significant bit (LSB). Lsb4 is the four least significant bits and the number of ones is counted by starting with the most significant bit (MSB). If the sum of the consecutive LSB ones in Msb4 and the consecutive MSB ones in Lsb4 is greater or equal to 5 then bit stuffing must be performed.