(cond-expand

    ;(chibi (include-shared "bit")

           ;(include "chibi-core.scm"))

    ((library (rnrs arithmetic bitwise))

      (import (only (rnrs arithmetic bitwise)

                    bitwise-not bitwise-and bitwise-ior bitwise-xor

                    bitwise-bit-count bitwise-length))

      (import (rename (only (rnrs arithmetic bitwise)

                            bitwise-arithmetic-shift bitwise-length)

                      (bitwise-arithmetic-shift arithmetic-shift)

                      (bitwise-length integer-length)))

      (define (bit-count i) ; Note, negative case different to R6RS bitwise-bit-count

         (if (>= i 0)

           (bitwise-bit-count i)

           (bitwise-bit-count (bitwise-not i)))))

    (gauche

      (import (only (gauche base)

                    integer-length))

      (import (rename (only (gauche base)

                            lognot logand logior logxor ash)

                      (lognot bitwise-not)

                      (logand bitwise-and)

                      (logior bitwise-ior)

                      (logxor bitwise-xor)

                      (ash arithmetic-shift))))

    (else (include "bitwise-core.scm")))

 

on the assumption that compiler inlining and such is more likely to work after import-with-renaming than after defining an equivalent function.

John Cowan          http://vrici.lojban.org/~cowan        xxxxxx@ccil.org

        Raffiniert ist der Herrgott, aber boshaft ist er nicht.

                --Albert Einstein