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-- $Date: 2003/12/23 12:57:33 $
-- $Revision: 1.7 $
-- $Author: jcrocholl $
package body Primes is
-- Tests if N is a prime number.
function Prime
(N : in Positive) -- The number to test.
return Boolean -- True if and only if N is prime.
is
D : Positive := 2;
begin
if N = 2 then return True; end if;
loop
if N mod D = 0 then return False; end if;
if N / D < D then return True; end if;
D := D + 1;
end loop;
end Prime;
-- Returns the smallest prime number that is greater or equal to N.
function Next_Prime
(N : in Positive) -- Start searching at this number.
return Positive -- The smallest prime number >= N.
is
Result : Positive := N;
begin
if Result mod 2 = 0 then
if Result = 2 then return 2; end if;
Result := Result + 1;
end if;
loop
exit when Prime(Result);
Result := Result + 2;
end loop;
return Result;
end Next_Prime;
end Primes;