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Sklansky adder algorithm

  1. Dec 12, 2015 #1
    Hello. I am unsure if this subforum is the right place for this question, but without any alternatives, I will dare to post it here.

    A few days ago I received an assignment which is about the creation in VHDL of a Sklansky adder. However, before I move to the coding part, I have trouble understanding the exact mechanics of the algorithm. Below you can see a pi is a picture I have found which shows the tree of a 16-bit Sklansky adder. I have already found the circuits that are represented by the black and grey boxes and I know that the triangles are just buffers.

    Assuming we add the 16-bit A and B, I know that I have to find the generate and propagate values for each pair of bits A(i) and B(i) which are produced from the following equations
    9bdb79f15f95e3e4cd4af7239b31fcc4.png and f5c0d5b45f53aae418e02be45891af1f.png
    I also know that at some point I will have to calculate carry values with the equation:
    2b427196f75af6c666f71efe13dd24d3.png

    but I can't find a detailed explanation about how all that ties together. I don't know which are the steps that take place after I get to the final "level" in the picture, which is depicted by the bottom most box (the one with the numbering 0:0, ... 15:0), and the professor who assign this has been less than helpful so far with cryptic explanations and confusing clarifications. I have no idea what happens after I am through with the black/grey components and the buffers. If someone can help me understand the basics and the flow of the algorithm, I will be grateful, even if it's only a link that offers the explanation I seek. Thank you


    http://i1140.photobucket.com/albums/n575/artdevil27/2015-12-12_183428_zpsvkvhsjvq.png?t=1449862983 [Broken]
     
    Last edited by a moderator: May 7, 2017
  2. jcsd
  3. Dec 17, 2015 #2
    Thanks for the post! This is an automated courtesy bump. Sorry you aren't generating responses at the moment. Do you have any further information, come to any new conclusions or is it possible to reword the post?
     
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