DocumentCode :
1042755
Title :
A New Basis for Shifters in General-Purpose Processors for Existing and Advanced Bit Manipulations
Author :
Hilewitz, Yedidya ; Lee, Ruby B.
Author_Institution :
Massachusetts Microprocessor Design Center, Intel Corp., Hudson, MA, USA
Volume :
58
Issue :
8
fYear :
2009
Firstpage :
1035
Lastpage :
1048
Abstract :
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.
Keywords :
instruction sets; logic design; microprocessor chips; advanced bit manipulation instruction; barrel shifter design; butterfly data path circuit; general-purpose processor; instruction set architecture; inverse butterfly circuit; log-shifter design; microprocessor; multimedia-mix unit; shifter functional unit; Arithmetic; Bioinformatics; Circuit synthesis; Cryptography; Data mining; Delay; Digital arithmetic; Instruction sets; Logic programming; Microprocessors; Scattering; Shifter; arithmetic; bit gather; bit manipulation; bit scatter; butterfly; circuit design; deposit; extract; instruction set architecture; inverse butterfly; microprocessor; mix; multimedia; parallel operations.; permutation; processor architecture; rotation; shift;
fLanguage :
English
Journal_Title :
Computers, IEEE Transactions on
Publisher :
ieee
ISSN :
0018-9340
Type :
jour
DOI :
10.1109/TC.2008.219
Filename :
4721365
Link To Document :
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