Audio decoder core constants rom optimization

Abstract

A ROM for storing constants used in both the MPEG-2 and AC-3 audio decoding algorithms. These constants include (i) matrixing constants for AC-3 and MPEG audio decoding algorithms and (ii) windowing coefficients for AC-3 and MPEG audio decoding algorithms. The ROM includes (a) a first partition for storing a first set of constants which are windowing coefficients for AC-3 decoding, (b) a second partition for storing a second set of constants which are constants used for pre-IFFT and post-IFFT steps of AC-3 decoding (Blkswflag=1), (c) a third partition for storing a third set of constants which are both IDCT coefficients for MPEG decoding and IFFT coefficients for AC-3 decoding, (d) a fourth partition for storing a fourth set of constants which are constants used for pre-IFFT and post-IFFT steps of AC-3 decoding (Blkswflag=0), and (e) a fifth partition for storing a fifth set of constants which are windowing coefficients for MPEG decoding. The first and fifth partitions store 256 windowing coefficients for AC-3 decoding and 256 windowing coefficients for MPEG decoding, respectively. The second partition stores 64 sine and 64 cosine coefficients for AC-3 pre- and post-IFFT steps (Blkswflag=1). The fourth partition stores 128 sine and 128 cosine coefficients for AC-3 pre- and post-IFFT steps (Blkswflag=1). And, the third partition stores 64 unique sine constants and 64 unique cosine coefficients.