IP2022 User’s Manual—Peripherals www.ubicom.com 303 4.9 Linear Feedback Shift Register Four linear feedback shift register (LFSR) units provide hardware
support  for  the  computation-intensive  inner  loops  of  algorithms
commonly used in data communications, such as: • Cyclic Redundancy Check (CRC) • Data Scrambling • Data Whitening • Encryption/Decryption • Hashing The LFSR units implement a programmable architecture, which
can be adapted for algorithms used by the Bluetooth, Ethernet,
Homeplug,    HomePNA,    HomeRF,    IEEE    802.11,    and    USB
communication     protocols.     Table     4-12     shows     the     LFSR
configurations used to support these protocols. Figure 4-15 is a
block diagram of the LFSR architecture. Table 4-12  LFSR Configurations for Various Protocols Proto- col Subfunc- tion D0 In Feed- back D Out USB CRC16 Din^D15 Din^D15 CRC5 Din^D4 Din^D4 Ether-
net CRC32 Din^D31 Din^D31 Scrambler Din^D17^D22 Din^D17^D22 Descram-
bler Din Din^D17^D22