Method and apparatus for compressing signals in a fixed point format without introducing a bias

A system for compressing an N-bit signal by K bits, wherein the signal is represented in a 2's complement format and K<N, and wherein bit 1 of the signal is the least significant bit and bit N of the signal is the most significant bit, comprising:

• first means for determining whether bit K of the signal is equal to "0", and if so, outputting the N-K most significant bits of the signal;
• second means for determining whether bit K of the signal is equal to "1", and if so, for determining whether bits K-1 through bit 1 of the signal are not all equal to "0", and if so, for adding "1" to the N-K most significant bits of bits of the signal and outputting the result of said addition;
• and
• third means for determining whether bit K of the signal is equal to "1", and if so, for determining whether bits K-1 through bit 1 of the signal are all equal to "0", and if so, for determining the oddness or evenness of the N-K most significant bits of the signal, and if even, for adding "1" to the N-K most significant bits of the signal and outputting the result of said addition, and if odd, for outputting the N-K most significant bits of the signal.

A system for compressing an N-bit signal by K bits, wherein the signal is represented in a 2's complement format and K<N, and wherein bit 1 of the signal is the least significant bit and bit N of the signal is the most significant bit, comprising:

• first OR means for determining whether one or more of bits 1 through K-1 of the signal is equal to "1", wherein said first OR means has a first output;
• first NOR means for determining whether said first output and bit K+1 of the signal are both "0", wherein said first NOR means has a second output;
• second OR means for determining whether either said first output or said second output is "1", wherein said second OR means has a third output;
• first AND means for determining whether said third output and bit K of the signal are both "1", wherein said first AND means has a fourth output;
• and
• an adder for adding said fourth output to the N-K most significant bits of the signal and outputting the result of said addition.