Patent ID: 7724772

Claim:
An apparatus for switching data in communication system, comprising: a conversion circuit used to receive a source data having a real coding dimension so as to convert the source data into a converted data having a tolerable coding dimension, wherein there is a judgment bit on the converted data so as to designate the judgment bit of the source data as a correct bit and to designate the judgment bit of the non-source data as an error bit, and the real coding dimension is not larger than the tolerable coding dimension; a shifter circuit used to shift the converted data certain shift amount so as to generate a shifted data, starting from the most significant bit (MSB) of the shifted data toward the least significant bit (LSB) of the shifted data, acquire a real coding dimension as a second data, and subtract the most significant bit of the shifted data by the bit of the real coding dimension as the starting bit of a first data, starting from the starting bit toward the direction of the least significant bit of the shifted data, acquire a real coding dimension as the first data, wherein if from the starting bit to the least significant bit of the shifted data is smaller than the real coding dimension, the acquisition will be continued from the most significant bit of the shifted data; and a comparison and selection circuit, through a comparison of the judgment bit in the first data and the second data, used to send out an output data, wherein the output data is data that is shifted by certain amount on the source data.