Source code in the futurebasic programming language

local fn IsPrime( n as NSUInteger ) as BOOL
  BOOL       isPrime = YES
  NSUInteger i
  
  if n < 2        then exit fn = NO
  if n = 2        then exit fn = YES
  if n mod 2 == 0 then exit fn = NO
  for i = 3 to int(n^.5) step 2
    if n mod i == 0 then exit fn = NO
  next
end fn = isPrime

void local fn DesecendingPrimes( limit as long )
  long i, n, mask, num, count = 0
  
  for i = 0 to limit -1
    n = 0 : mask = i : num = 9
    while ( mask )
      if mask & 1 then n = n * 10 + num
      mask = mask >> 1
      num--
    wend
    mda(i) = n
  next
  
  mda_sort @"compare:"
  
  for i = 1 to mda_count (0) - 1
    n = mda_integer(i)
    if ( fn IsPrime( n ) )
      printf @"%10ld\b", n
      count++
      if count mod 10 == 0 then print
    end if
  next
  printf @"\n\n\tThere are %ld descending primes.", count
end fn

window 1, @"Desecending Primes", ( 0, 0, 780, 230 )
print

CFTimeInterval t
t = fn CACurrentMediaTime
fn DesecendingPrimes( 512 )
printf @"\n\tCompute time: %.3f ms\n",(fn CACurrentMediaTime-t)*1000

HandleEvents