Dvd data descrambler for host interface and mpeg interface

Abstract

A descrambler for a Digital Versatile Disk (DVD) is provided within a DVD controller to allow for real-time descrambling of DVD data from the DVD buffer. The built-in descrambler also allows the controller to interface with a Host Adapter (e.g., ATAPI Host) or MPEG II decoder. The descrambling circuit reads four bits of an identifier portion of each sector. These four bits are used to access a look up table LUT in the descrambler for retrieving a 15 bit seed. The fifteen bit seed is used to generate a descrambling patter, which, when XORed with scrambled data, will descramble data on a byte-by-byte basis. The descrambling pattern is generated on a flash basis, by performing eight shift operations and XOR operations simultaneously, allowing for descrambling one byte per clock cycle. In the preferred embodiment, the flash descrambler may use a programmed register transfer logic (RTL) to generate sixteen bits of descrambling pattern at a time, to allow for descrambling on a word-by-word basis at the rate of one word per clock cycle.