samples/shootout/nsievebits.io

   1 #!/usr/bin/env io
   2
   3 /* The Great Computer Language Shootout
   4    http://shootout.alioth.debian.org
   5
   6    contributed by Ian Osgood */
   7
   8 Sequence pad := method(w, s:=self; while (s size < w, s=" ".. s) )
   9 Number clearBit := method(b, &(1 clone shiftLeft(b) bitwiseComplement) )
  10
  11 sieve := Object clone do(
  12     flags := Sequence clone do(
  13         isSet := method(i, at(i/8) at(i%8) != 0)
  14         clear := method(i, atPut(i/8, at(i/8) clearBit(i%8) ) )
  15     )
  16     show := method(n,
  17         flags setSize((n/8) ceil)
  18         for (i, 0, flags size - 1, flags atPut(i, 255))
  19         primes := 0
  20         for (i, 2, n-1,
  21             if (flags isSet(i),
  22                 primes = primes + 1
  23                 if (i+i < n, for (j, i+i, n-1, i, flags clear(j) ) )
  24             )
  25         )
  26         writeln("Primes up to", n asString pad(9), primes asString pad(9))
  27     )
  28 )
  29
  30 n := System args at(1) asNumber
  31 sieve show(10000 shiftLeft(n))
  32 sieve show(10000 shiftLeft(n-1))
  33 sieve show(10000 shiftLeft(n-2))