| 摘要 |
The present invention discloses a system and system of performing an add-compare-select butterfly operation in an implementation of the Viterbi algorithm. The system includes a first memory element for storing a plurality of source state metrics. The first memory element is coupled to a multiplexer which is capable of selecting between a first and second operating path based on even and odd clock cycles. The multiplexer is coupled to an add-compare-select mechanism, which calculates the target state metrics for each of the source state metrics. A second storage element, coupled to the add-compare-select mechanism and the multiplexer, is used to temporarily store the target state metrics while a third storage element stores a predetermined logic bit which corresponds to the lowest value target state metric. The multiplexer therefore selects the first operating path during even clock cycles and supplies the source state metrics from the first memory element to the add-compare-select mechanism to generate target state metrics. During odd clock cycles, the multiplexer selects the second operating path to access the second memory element and use the previously calculated target state metrics as intermediate source state metrics, such that the add-compare-select mechanism generates the target state metrics based on the intermediate source state metrics.
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