primes.nim

import os, times, future, math, sequtils, strutils

proc get_primes7(n: int32): seq[int32] =
  if n < 2:
    return @[]

  result = @[2'i32]

  if n == 2:
    return

  var s = newSeq[int32]()

  for x in countup(3, n + 1, 2):
    s.add(x)

  let
    mroot = int32(sqrt(n.float))
    half = int32(len(s))
  var
    i = 0'i32
    m = 3'i32

  while m <= mroot:
    if s[i] != 0:
      var j = (m * m - 3) div 2  # int div
      s[j] = 0
      while j < half:
        s[j] = 0
        j += m
    inc(i)
    m = 2 * i + 3

  for x in s:
    if x != 0:
      result.add(x)

let start_time = getTime()
let period_time = getEnv("RUN_TIME").parseInt()

while int(getTime() - start_time) < period_time:
  let res = get_primes7(10000000)
  echo("Found $1 prime numbers." % $res.len)