Importance

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Abstract

A subcode R-W channel data de-interleaving and de-scrambling method and apparatus includes the ability to de-interleave and de-scramble the encoded subchannel data without the necessity of storage elements, by dynamically calculating the final location of each byte of data within a packet as it is read from the CD-Rom. A pack counter monitors the pack number of the current byte of data. An index counter monitors the location of the current data within a pack. A subtractor uses the values from the pack counter and the index counter to obtain an input value, a first portion of which is supplied to a first offset generator. A second portion of the subtractor output is used to select a base address. The first offset generator determines the pack number of the current byte of data after the de-interleave process. A second offset generator receives a value from the index counter and generates a corresponding value. The results from the first offset generator and the second offset generator are both input into a first adder. The output of the first adder is added to the selected base address by a second adder in order to calculate the final address. The final address is transmitted with the current byte of data to an external buffer memory, where it is stored in the specified address. Preferably the present invention is included in a dedicated integrated circuit which calculates the final address of each byte of subchannel R-W data as it is read.

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First Claim