Gambit-C is already almost 100% compliant with SRFI 33.

Great. Marc, would you email me the Gambit API for inclusion in the
related-designs section? I could not find it in your doc; I checked
(of course).

    Kawa follows the Guile names:
    logand i1 ...
    logior i1 ...
    logxor i1 ...
    lognot i
    logtest i j - same as (not (zero? (logand i j)))
    logbit? i pos
    logop op x y - Perform one of the 16 bitwise operations of
       x and y, depending on op.
    arithmetic-shift i j
    ash i j (synonym for arithmetic-shift)
    logcount i
    integer-length i
    bit-extract n start end

Per! Thank you for showing up with the Kawa API. I will include it in
the related-designs summary.
    -Olin