-/* $NetBSD: primes.c,v 1.7 1997/10/12 01:04:55 lukem Exp $ */
+/* $NetBSD: primes.c,v 1.17 2009/08/12 08:25:27 dholland Exp $ */
/*
* Copyright (c) 1989, 1993
* 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. All advertising materials mentioning features or use of this software
- * must display the following acknowledgement:
- * This product includes software developed by the University of
- * California, Berkeley and its contributors.
- * 4. Neither the name of the University nor the names of its contributors
+ * 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.
*
#include <sys/cdefs.h>
#ifndef lint
-__COPYRIGHT("@(#) Copyright (c) 1989, 1993\n\
- The Regents of the University of California. All rights reserved.\n");
+__COPYRIGHT("@(#) Copyright (c) 1989, 1993\
+ The Regents of the University of California. All rights reserved.");
#endif /* not lint */
#ifndef lint
#if 0
static char sccsid[] = "@(#)primes.c 8.5 (Berkeley) 5/10/95";
#else
-__RCSID("$NetBSD: primes.c,v 1.7 1997/10/12 01:04:55 lukem Exp $");
+__RCSID("$NetBSD: primes.c,v 1.17 2009/08/12 08:25:27 dholland Exp $");
#endif
#endif /* not lint */
*
* We make TABSIZE large to reduce the overhead of inner loop setup.
*/
-char table[TABSIZE]; /* Eratosthenes sieve of odd numbers */
+static 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 ubig prime[];
-extern ubig *pr_limit; /* largest prime in the prime array */
+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 char pattern[];
-extern int pattern_size; /* length of pattern array */
+extern const char pattern[];
+extern const int pattern_size; /* length of pattern array */
-int main __P((int, char *[]));
-void primes __P((ubig, ubig));
-ubig read_num_buf __P((void));
-void usage __P((void));
+static int dflag;
+
+static void primes(ubig, ubig);
+static ubig read_num_buf(void);
+static void usage(void) __dead;
int
-main(argc, argv)
- int argc;
- char *argv[];
+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)
+ while ((ch = getopt(argc, argv, "d")) != -1)
switch (ch) {
+ case 'd':
+ dflag++;
+ break;
case '?':
default:
usage();
* This routine returns a number n, where 0 <= n && n <= BIG.
*/
ubig
-read_num_buf()
+read_num_buf(void)
{
ubig val;
char *p, buf[100]; /* > max number of digits. */
/*
* 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(start, stop)
- ubig start; /* where to start generating */
- ubig stop; /* don't generate at or above this value */
+primes(ubig start, ubig stop)
{
char *q; /* sieve spot */
ubig factor; /* index and factor */
char *tab_lim; /* the limit to sieve on the table */
- ubig *p; /* prime table pointer */
+ const ubig *p; /* prime table pointer */
ubig fact_lim; /* highest prime for current block */
+ ubig mod; /* temp storage for mod */
+ ubig prev = 0;
/*
* A number of systems can not convert double values into unsigned
for (p = &prime[0], factor = prime[0];
factor < stop && p <= pr_limit; factor = *(++p)) {
if (factor >= start) {
- printf("%lu\n", (unsigned long) factor);
+ printf("%lu", (unsigned long) factor);
+ if (dflag) {
+ printf(" (%lu)",
+ (unsigned long) factor - prev);
+ }
+ putchar('\n');
}
+ prev = factor;
}
/* return early if we are done */
if (p <= pr_limit) {
p = &prime[7]; /* 19 is next prime, pi(19)=7 */
do {
/* determine the factor's initial sieve point */
- q = (char *)(start%factor); /* temp storage for mod */
- if ((long)q & 0x1) {
- q = &table[(factor-(long)q)/2];
+ mod = start%factor;
+ if (mod & 0x1) {
+ q = &table[(factor-mod)/2];
} else {
- q = &table[q ? factor-((long)q/2) : 0];
+ q = &table[mod ? factor-(mod/2) : 0];
}
- /* sive for our current factor */
+ /* sieve for our current factor */
for ( ; q < tab_lim; q += factor) {
*q = '\0'; /* sieve out a spot */
}
*/
for (q = table; q < tab_lim; ++q, start+=2) {
if (*q) {
- printf("%lu\n", (unsigned long) start);
+ printf("%lu", (unsigned long) start);
+ if (dflag) {
+ printf(" (%lu)",
+ (unsigned long) start - prev);
+ prev = start;
+ }
+ putchar('\n');
}
}
}
}
void
-usage()
+usage(void)
{
- (void)fprintf(stderr, "usage: primes [start [stop]]\n");
+ (void)fprintf(stderr, "usage: primes [-d] [start [stop]]\n");
exit(1);
}
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