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primegen(3)           DragonFly Library Functions Manual           primegen(3)

NAME
       primegen - enumerate small primes

SYNTAX
       #include <primegen.h>

       void primegen_init(&pg);
       uint64 primegen_next(&pg);
       uint64 primegen_peek(&pg);
       uint64 primegen_count(&pg,bound);
       void primegen_skipto(&pg,bound);

       struct primegen pg;
       uint64 bound;

DESCRIPTION
       The primegen library generates prime numbers in order: 2, 3, 5, 7, etc.
       It can generate primes as large as 10^15.

       The simplest way to use primegen is to call primegen_init and then call
       primegen_next repeatedly.  The first call to primegen_next will return
       2; the next call will return 3; the next call will return 5; and so on.

       At each moment the next few primes to be returned by primegen_next are
       buffered inside pg.  primegen_init initializes pg with the first few
       primes, starting at 2.  You must initialize pg with primegen_init
       before using pg with any of the other primegen routines.  You may call
       primegen_init again to start over at 2.

       primegen_next returns the next buffered prime and removes that prime
       from pg.  primegen_peek returns the next buffered prime but does not
       change pg.

       primegen_skipto discards all primes up to bound.  It has the same
       effect as

            while (primegen_peek(&pg) < bound)
              primegen_next(&pg);

       primegen_count discards all primes up to bound and returns the number
       of primes discarded.

       You can set up several independent generators; all primegen data is
       stored in pg.  Beware, however, that each struct primegen uses quite a
       bit of memory.

SEE ALSO
       primes(1), primespeed(1)

                                                                   primegen(3)