Title
Reducing the cost of floating-point mantissa alignment and normalization in FPGAs
Abstract
In floating-point datapaths synthesized on FPGAs, the shifters that perform mantissa alignment and normalization consume a disproportionate number of LUTs. Shifters are implemented using several rows of small multiplexers; unfortunately, multiplexer-based logic structures map poorly onto LUTs. FPGAs, meanwhile, contain a large number of multiplexers in the programmable routing network; these multiplexer are placed under static control of the FPGA's configuration bitstream. In this work, we modify some of the routing multiplexers in the intra-cluster routing network of a CLB in an FPGA to implement shifters for floating-point mantissa alignment and normalization; the number of CLBs required for these operations is reduced by 67%. If shifting is not required, the routing multiplexers that have been modified can be configured to operate as normal routing multiplexers, so no functionality is sacrificed. The area overhead incurred by these modifications is small, and there is no need to modify every routing multiplexer in the FPGA. Experiments show that there is no negative impact in terms of clock frequency or routability for benchmarks that do not use the dynamic multiplexers.
Year
DOI
Venue
2012
10.1145/2145694.2145738
FPGA
Keywords
Field
DocType
programmable routing network,floating-point datapaths,dynamic multiplexers,intra-cluster routing network,large number,disproportionate number,routing multiplexer,routing multiplexers,small multiplexers,normal routing multiplexers,floating-point mantissa alignment,normalization,field programmable gate array,floating point
Row,Normalization (statistics),Computer science,Floating point,Parallel computing,Field-programmable gate array,Multiplexer,Real-time computing,Bitstream,Significand,Clock rate
Conference
Citations 
PageRank 
References 
3
0.48
20
Authors
6
Name
Order
Citations
PageRank
Yehdhih Ould Mohammed Moctar1181.82
Nithin George2384.08
Hadi Parandeh-Afshar313412.24
Paolo Ienne42246199.26
Guy G.F. Lemieux5535.06
Philip Brisk678660.63