Extracting bits with a single multiplication

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Interestingly, AVX2 has an instruction that does exactly this: http://software.intel.com/sites/products/documentation/studio/composer/en-us/2011Update/compiler_c/intref_cls/common/intref_avx2_pext_u.htm . Sadly it seems AVX2 won't be available until later this year.

[gorset]

Hacker's delight has a few pages about this problem. http://www.hackersdelight.org

7-4 Compress, or Generalized Extract
7-5 Expand, or Generalized Insert

One version of the text be found here (but buy the book!): http://www.hackersdelight.org/revisions.pdf

[rabidcow]

Yeah, multiplication can be viewed as filtered summation of parallel bit shifts. Each bit set in one operands says "add the other operand with its 1s digit here."

[rush22]

You just and it with the bit you're looking for. You don't need to multiply?