addons/Loki/samples/shootout/nsieve-bits.io

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