Fixed-point analysis and simulations of AC-3 algorithm

We perform a fixed-point analysis for the Dolby AC-3 audio decoding algorithm, and determine the suitable multiplier wordlength (say, N) satisfying the required sound quality. Then, based on the similar simulations, we try to reduce the accumulator wordlength from the usual (8+2N) to (g+N+r) where g is the wordlength for overflow guard bits and r is the wordlength for rounding with the condition r