System and method for shared decoding

1. A method for concurrently decoding a plurality of data streams comprising:

decoding a first portion of a first data stream in said plurality of data streams, said first data stream having a state associated therewith following said decoding of said first portion;

decoding portions of other data streams in said plurality of data streams;

restoring said state associated with said first data stream; and

decoding a second portion of said first data stream in said plurality of data streams.

2. The method as in claim 1 wherein each of said plurality of data streams has a memory array associated therewith, said memory arrays storing states associated with each of said data streams, and wherein restoring said state associated with said first data stream comprises switching to processing data through said memory array associated with said first state.

3. The method as in claim 1 wherein decoding comprises Viterbi decoding and said state comprises survivor path data associated with said Viterbi decoding.

4. The method as in claim 3 wherein said state further comprises a plurality of path metric values.

5. An apparatus comprising:

a decoder to decode a plurality of data streams, said decoder having a state associated with each of said plurality of data streams at any given time, said state being an arbitrary one of a set of possible states;

a state restoration logic to dynamically restore said decoder's state upon switching from decoding one data stream to another data stream.

6. The apparatus as in claim 5 herein said IC further comprises:

one or more memory arrays for storing said state associated with each of said plurality of data streams.

7. The apparatus as in claim 6 wherein said one or more memory arrays are equal in number to said plurality of data streams decoded by said decoder.

8. The apparatus as in claim 7 wherein said decoder is a Viterbi decoder.

9. The apparatus as in claim 8 wherein said one or more memory arrays are forward-tracing decode arrays.

10. The apparatus as in claim 8 wherein said state restoration logic further comprises:

an accumulator buffer for temporarily storing accumulator values associated with each of said plurality of data streams, said accumulator values representing path metric values and being readable from said accumulator buffer to restore said state.

11. The apparatus as in claim 7 wherein said state associated with each of said data streams is described by a trellis diagram.

12. The apparatus as in claim 11 wherein said state associated with each of said plurality of data streams are comprised of survivor path data.

13. The apparatus as in claim 7 wherein each of said plurality of data streams comprises multimedia data transmitted from a satellite transponder.

14. A method for intermittently decoding a data stream, the method comprising:

performing a decoding operation on said data stream, said decoding operation being characterized at any given time by state information as the decoding operation is performed;

suspending performance of the decoding operation;

storing said state information for the point at which said decoding operation was suspended; and

after completion of said suspending step, resuming said decoding operation using the stored state information to establish an initial state for said decoding operation going forward from the time when said resuming begins.

15. The method as in claim 14 further comprising:

performing a task unrelated to said decoding operation during said suspending step.

16. The method as in claim 15 , wherein said data stream is a first data stream, and said task is performing a decoding operation on a second data stream distinct from said first data stream.

17. The method as in claim 15 wherein said storing step comprises storing said state information in a memory array, and wherein said resuming step comprises retrieving said state information from said memory array.

18. The method as in claim 15 wherein performing said decoding operation comprises performing a Viterbi algorithm, and said state information comprises survivor path data associated with said Viterbi algorithm.

19. The method as in claim 18 wherein said state information further comprises path metric values.

20. The method as in claim 15 wherein said data stream is encoded using a non-block code.

21. The method as in claim 20 wherein said code is a convolutional code.