Datapath design problem?

Jan 26, 2007 2 Replies
S

Hi all,



I am reading "Coding Guidelines for Datapath Synthesis" from Synopsys.



It says "The most important technique to improve the performance of a datapath is to avoid expensive carry-propagations and to make use of redundant representations instead (like carry-save or partial-product) wherever possible."


  1. Is there any article talk about what's "carry-propagation" and how to avoid use it?
  2. What's "redundant representations" mean?

Please recommend some readings about it, thanks in advance!



Best regards, Davy



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J

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Happy reading,

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R

That really is targeted to ASIC implementations. The performance hit for carry propagation in FPGAs that have a "fast carry chain" is mitigated by the much faster carry propagation on these special dedicated circuits. With that in mind, if you are designing on an FPGA with fast carry logic, then this admonishment doesn't apply.

Redundant representations refer to alternative number system representations that avoid the propagation of a carry signal across the width of a data word as a result of arithmetic operations. They are not,however, without their own hardships.

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