Method and apparatus for storing survivor paths in a viterbi detector using systematic pointer exchange

1. A survivor path memory for a Viterbi detector, comprising:

a plurality of columns, each of said columns associated with a different time step, each of said columns comprising:

a memory element for storing one bit or portion of a bit sequence associated with a Viterbi state, each of said memory elements having at least one data input; and

a switch for each state controlled by a case signal indicating a time step, said switch selecting a state from a previous time step, wherein an output of said switch of a given state is connected to said at least one data input of a memory element of said given state; and

an input processor for generating a control signal that exchanges one or more pointers based on a trellis structure, wherein each of said pointers points to one of said memory elements.

2. The survivor path memory of claim 1 , wherein one or more of said states maintain values and wherein said associated pointers are maintained in said associated memory elements.

3. The survivor path memory of claim 1 , wherein one or more of said memory elements are updated based on a value of a write enable signal.

4. The survivor path memory of claim 1 , wherein an output of each of said memory elements is stored in a corresponding buffer, and wherein said buffer contents are read based on a value of a read enable signal.

5. The survivor path memory of claim 1 , wherein one or more of said memory elements are updated based on a value provided by an input processor.

6. The survivor path memory of claim 1 , wherein said trellis structure comprises one or more butterfly trellises.

7. The survivor path memory of claim 1 , wherein said trellis structure has been collapsed to combine a plurality of steps into a single step.

8. The survivor path memory of claim 1 , wherein one or more of said states do not change values and wherein said associated pointers are not updated by said one or more predefined rules.