Scheduled System Maintenance:
Some services will be unavailable Sunday, March 29th through Monday, March 30th. We apologize for the inconvenience.
By Topic

A New Basis for Shifters in General-Purpose Processors for Existing and Advanced Bit Manipulations

Sign In

Cookies must be enabled to login.After enabling cookies , please use refresh or reload or ctrl+f5 on the browser for the login options.

The purchase and pricing options are temporarily unavailable. Please try again later.
2 Author(s)
Hilewitz, Y. ; Massachusetts Microprocessor Design Center, Intel Corp., Hudson, MA, USA ; Lee, R.B.

This paper describes a new basis for the implementation of the shifter functional unit in microprocessors that can implement new advanced bit manipulations as well as standard shifter operations. Our design is based on the inverse butterfly and butterfly data path circuits, rather than the barrel shifter or log-shifter designs currently used. We show how this new shifter can implement the standard shift and rotate operations, as well as more advanced extract, deposit, and mix operations found in some processors. Furthermore, it can perform important new classes of even more advanced bit manipulation instructions like arbitrary bit permutations, bit gather (or parallel extract), and bit scatter (or parallel deposit) instructions. Thus, our new functional unit performs the functionality of three functional units-the basic shifter, the multimedia-mix unit, and the advanced bit manipulation functional unit, while having a latency only slightly longer than that of the log-shifter. For performing only the existing functions of a shifter, it has significantly smaller area.

Published in:

Computers, IEEE Transactions on  (Volume:58 ,  Issue: 8 )