OpenBSD-4.6/games/primes/primes.c
/* $OpenBSD: primes.c,v 1.14 2007/09/06 20:50:55 chl Exp $ */
/* $NetBSD: primes.c,v 1.5 1995/04/24 12:24:47 cgd Exp $ */
/*
* Copyright (c) 1989, 1993
* The Regents of the University of California. All rights reserved.
*
* This code is derived from software contributed to Berkeley by
* Landon Curt Noll.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* 3. Neither the name of the University nor the names of its contributors
* may be used to endorse or promote products derived from this software
* without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*/
#ifndef lint
static char copyright[] =
"@(#) Copyright (c) 1989, 1993\n\
The Regents of the University of California. All rights reserved.\n";
#endif /* not lint */
#ifndef lint
#if 0
static char sccsid[] = "@(#)primes.c 8.5 (Berkeley) 5/10/95";
#else
static char rcsid[] = "$OpenBSD: primes.c,v 1.14 2007/09/06 20:50:55 chl Exp $";
#endif
#endif /* not lint */
/*
* primes - generate a table of primes between two values
*
* By: Landon Curt Noll chongo@toad.com, ...!{sun,tolsoft}!hoptoad!chongo
*
* chongo <for a good prime call: 391581 * 2^216193 - 1> /\oo/\
*
* usage:
* primes [start [stop]]
*
* Print primes >= start and < stop. If stop is omitted,
* the value 4294967295 (2^32-1) is assumed. If start is
* omitted, start is read from standard input.
*
* validation check: there are 664579 primes between 0 and 10^7
*/
#include <sys/types.h>
#include <ctype.h>
#include <err.h>
#include <errno.h>
#include <limits.h>
#include <math.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include "primes.h"
/*
* Eratosthenes sieve table
*
* We only sieve the odd numbers. The base of our sieve windows are always
* odd. If the base of table is 1, table[i] represents 2*i-1. After the
* sieve, table[i] == 1 if and only iff 2*i-1 is prime.
*
* We make TABSIZE large to reduce the overhead of inner loop setup.
*/
char table[TABSIZE]; /* Eratosthenes sieve of odd numbers */
/*
* prime[i] is the (i+1)th prime.
*
* We are able to sieve 2^32-1 because this byte table yields all primes
* up to 65537 and 65537^2 > 2^32-1.
*/
extern const ubig prime[];
extern const ubig *pr_limit; /* largest prime in the prime array */
/*
* To avoid excessive sieves for small factors, we use the table below to
* setup our sieve blocks. Each element represents a odd number starting
* with 1. All non-zero elements are factors of 3, 5, 7, 11 and 13.
*/
extern const char pattern[];
extern const int pattern_size; /* length of pattern array */
void primes(ubig, ubig);
ubig read_num_buf(void);
void usage(void);
int
main(int argc, char *argv[])
{
ubig start; /* where to start generating */
ubig stop; /* don't generate at or above this value */
int ch;
char *p;
while ((ch = getopt(argc, argv, "")) != -1)
switch (ch) {
case '?':
default:
usage();
}
argc -= optind;
argv += optind;
start = 0;
stop = BIG;
/*
* Convert low and high args. Strtoul(3) sets errno to
* ERANGE if the number is too large, but, if there's
* a leading minus sign it returns the negation of the
* result of the conversion, which we'd rather disallow.
*/
switch (argc) {
case 2:
/* Start and stop supplied on the command line. */
if (argv[0][0] == '-' || argv[1][0] == '-')
errx(1, "negative numbers aren't permitted.");
errno = 0;
start = strtoul(argv[0], &p, 10);
if (errno)
err(1, "%s", argv[0]);
if (*p != '\0')
errx(1, "%s: illegal numeric format.", argv[0]);
errno = 0;
stop = strtoul(argv[1], &p, 10);
if (errno)
err(1, "%s", argv[1]);
if (*p != '\0')
errx(1, "%s: illegal numeric format.", argv[1]);
break;
case 1:
/* Start on the command line. */
if (argv[0][0] == '-')
errx(1, "negative numbers aren't permitted.");
errno = 0;
start = strtoul(argv[0], &p, 10);
if (errno)
err(1, "%s", argv[0]);
if (*p != '\0')
errx(1, "%s: illegal numeric format.", argv[0]);
break;
case 0:
start = read_num_buf();
break;
default:
usage();
}
if (start > stop)
errx(1, "start value must be less than stop value.");
primes(start, stop);
exit(0);
}
/*
* read_num_buf --
* This routine returns a number n, where 0 <= n && n <= BIG.
*/
ubig
read_num_buf(void)
{
ubig val;
char *p, buf[100]; /* > max number of digits. */
for (;;) {
if (fgets(buf, sizeof(buf), stdin) == NULL) {
if (ferror(stdin))
err(1, "stdin");
exit(0);
}
buf[strcspn(buf, "\n")] = '\0';
for (p = buf; isblank(*p); ++p);
if (*p == '\0')
continue;
if (*p == '-')
errx(1, "negative numbers aren't permitted.");
errno = 0;
val = strtoul(buf, &p, 10);
if (errno)
err(1, "%s", buf);
for (; isblank(*p); ++p);
if (*p != '\0')
errx(1, "%s: illegal numeric format.", buf);
return (val);
}
}
/*
* primes - sieve and print primes from start up to and but not including stop
* start: where to start generating
* stop : don't generate at or above this value
*/
void
primes(ubig start, ubig stop)
{
char *q; /* sieve spot */
ubig factor; /* index and factor */
char *tab_lim; /* the limit to sieve on the table */
const ubig *p; /* prime table pointer */
ubig fact_lim; /* highest prime for current block */
ubig mod;
/*
* A number of systems can not convert double values into unsigned
* longs when the values are larger than the largest signed value.
* We don't have this problem, so we can go all the way to BIG.
*/
if (start < 3) {
start = (ubig)2;
}
if (stop < 3) {
stop = (ubig)2;
}
if (stop <= start) {
return;
}
/*
* be sure that the values are odd, or 2
*/
if (start != 2 && (start&0x1) == 0) {
++start;
}
if (stop != 2 && (stop&0x1) == 0) {
++stop;
}
/*
* quick list of primes <= pr_limit
*/
if (start <= *pr_limit) {
/* skip primes up to the start value */
for (p = &prime[0], factor = prime[0];
factor < stop && p <= pr_limit; factor = *(++p)) {
if (factor >= start) {
printf("%lu\n", (unsigned long) factor);
}
}
/* return early if we are done */
if (p <= pr_limit) {
return;
}
start = *pr_limit+2;
}
/*
* we shall sieve a bytemap window, note primes and move the window
* upward until we pass the stop point
*/
while (start < stop) {
/*
* factor out 3, 5, 7, 11 and 13
*/
/* initial pattern copy */
factor = (start%(2*3*5*7*11*13))/2; /* starting copy spot */
memcpy(table, &pattern[factor], pattern_size-factor);
/* main block pattern copies */
for (fact_lim=pattern_size-factor;
fact_lim+pattern_size<=TABSIZE; fact_lim+=pattern_size) {
memcpy(&table[fact_lim], pattern, pattern_size);
}
/* final block pattern copy */
memcpy(&table[fact_lim], pattern, TABSIZE-fact_lim);
/*
* sieve for primes 17 and higher
*/
/* note highest useful factor and sieve spot */
if (stop-start > TABSIZE+TABSIZE) {
tab_lim = &table[TABSIZE]; /* sieve it all */
fact_lim = (int)sqrt(
(double)(start)+TABSIZE+TABSIZE+1.0);
} else {
tab_lim = &table[(stop-start)/2]; /* partial sieve */
fact_lim = (int)sqrt((double)(stop)+1.0);
}
/* sieve for factors >= 17 */
factor = 17; /* 17 is first prime to use */
p = &prime[7]; /* 19 is next prime, pi(19)=7 */
do {
/* determine the factor's initial sieve point */
mod = start % factor;
if (mod & 0x1)
q = &table[(factor - mod)/2];
else
q = &table[mod ? factor-(mod/2) : 0];
/* sieve for our current factor */
for ( ; q < tab_lim; q += factor) {
*q = '\0'; /* sieve out a spot */
}
} while ((factor=(ubig)(*(p++))) <= fact_lim);
/*
* print generated primes
*/
for (q = table; q < tab_lim; ++q, start+=2) {
if (*q) {
printf("%lu\n", (unsigned long) start);
}
}
}
}
void
usage(void)
{
(void)fprintf(stderr, "usage: primes [start [stop]]\n");
exit(1);
}