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Variable length decoder and method for decoding two codes per clock cycle (Variable length decoder and method for decoding two codes per clock cycle)
Variable length decoder and method for decoding two codes per clock cycle (Variable length decoder and method for decoding two codes per clock cycle)
The present invention relates to an apparatus and method for determining the length of a plurality of variable length coded data values contained in a data stream in a single clock cycle. The apparatus includes a shifter for receiving a data stream. The shifter transmits a subset of a plurality of variable length coded data values in response to a shift control signal. The first length decoding mechanism is coupled to receive a subset of a plurality of variable length coded data values in response to a plurality of control signals. The first length decoding mechanism performs a first length decoding operation to determine the length of the first of the encoded data values in the subset. The second length decoding mechanism also determines the length of the second of the plurality of encoded data values. The second coded data value determines the length of the second one of the first coded data values in the subset. The second length decoding mechanism is also coupled to receive a subset of the plurality of encoded data values. The second length decoding mechanism performs a second decoding operation to determine the length of the second of the encoded data values in the subset. The second coded data value immediately follows the first coded data value in the subset. The first and second decryption operations are performed simultaneously. The combined length decoder outputs the combined length of the first and second data values in response to the length of the first and second encoded data values. The shift controller forms a shift control signal in response to the combined length of the first and second data values. The shift control signal identifies the location of the next encoded data value in the shifter. The next coded data value immediately follows the second coded data value. The shift controller sends the signal to the shifter.
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