primesieve_iterator.h File Reference

primesieve_iterator allows to easily iterate over primes both forwards and backwards. More...

#include <stdint.h>
#include <stddef.h>

Include dependency graph for primesieve_iterator.h:

This graph shows which files directly or indirectly include this file:

Classes
struct	primesieve_iterator
	C prime iterator, please refer to primesieve_iterator.h for more information. More...

Functions
void	primesieve_init (primesieve_iterator *pi)
	Initialize the primesieve iterator before first using it. More...
void	primesieve_free_iterator (primesieve_iterator *pi)
	Free all memory. More...
void	primesieve_skipto (primesieve_iterator *pi, uint64_t start, uint64_t stop_hint)
	Set the primesieve iterator to start. More...
static uint64_t	primesieve_next_prime (primesieve_iterator *pi)
	Get the next prime. More...
static uint64_t	primesieve_previous_prime (primesieve_iterator *pi)
	Get the previous prime, or 0 if input <= 2 e.g. More...

Detailed Description

primesieve_iterator allows to easily iterate over primes both forwards and backwards.

Generating the first prime has a complexity of O(r log log r) operations with r = n^0.5, after that any additional prime is generated in amortized O(log n log log n) operations. The memory usage is about pi(n^0.5) * 16 bytes. primesieve_iterator objects are very convenient to use at the cost of being slightly slower than the primesieve_callback_primes() functions.

The primesieve_iterator.c example shows how to use primesieve_iterator. If any error occurs errno is set to EDOM and primesieve_next_prime() and primesieve_previous_prime() return PRIMESIEVE_ERROR.

Copyright (C) 2015 Kim Walisch, kim.w.nosp@m.alis.nosp@m.ch@gm.nosp@m.ail..nosp@m.com

This file is distributed under the BSD License. See the COPYING file in the top level directory.

Function Documentation

void primesieve_free_iterator

(

primesieve_iterator *

pi

)

Free all memory.

Examples:

previous_prime.c, and primesieve_iterator.c.

void primesieve_init

(

primesieve_iterator *

pi

)

Initialize the primesieve iterator before first using it.

Examples:

previous_prime.c, and primesieve_iterator.c.

static uint64_t primesieve_next_prime ( primesieve_iterator *  pi )

inlinestatic

Get the next prime.

Examples:

primesieve_iterator.c.

static uint64_t primesieve_previous_prime ( primesieve_iterator *  pi )

inlinestatic

Get the previous prime, or 0 if input <= 2 e.g.

previous_prime(2) = 0.

Examples:

previous_prime.c.

void primesieve_skipto	(	primesieve_iterator *	pi,
		uint64_t	start,
		uint64_t	stop_hint
	)

Set the primesieve iterator to start.

Parameters

start	Generate primes > start (or < start).
stop_hint	Stop number optimization hint. E.g. if you want to generate the primes below 1000 use stop_hint = 1000, if you don't know use primesieve_get_max_stop().

Precondition

start <= 2^64 - 2^32 * 10

Examples:

previous_prime.c.