4.4BSD/usr/src/games/factor/factor.c
/*
* 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. 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
* 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
static char sccsid[] = "@(#)factor.c 8.1 (Berkeley) 5/31/93";
#endif /* not lint */
/*
* factor - factor a number into primes
*
* By: Landon Curt Noll chongo@toad.com, ...!{sun,tolsoft}!hoptoad!chongo
*
* chongo <for a good prime call: 391581 * 2^216193 - 1> /\oo/\
*
* usage:
* factor [number] ...
*
* The form of the output is:
*
* number: factor1 factor1 factor2 factor3 factor3 factor3 ...
*
* where factor1 < factor2 < factor3 < ...
*
* If no args are given, the list of numbers are read from stdin.
*/
#include <ctype.h>
#include <limits.h>
#include <stdio.h>
#include "primes.h"
/*
* 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 */
#define MAX_LINE 255 /* max line allowed on stdin */
void pr_fact(); /* print factors of a value */
long small_fact(); /* find smallest factor of a value */
char *read_num_buf(); /* read a number buffer */
char *program; /* name of this program */
main(argc, argv)
int argc; /* arg count */
char *argv[]; /* the args */
{
int arg; /* which arg to factor */
long val; /* the value to factor */
char buf[MAX_LINE+1]; /* input buffer */
/* parse args */
program = argv[0];
if (argc >= 2) {
/* factor each arg */
for (arg=1; arg < argc; ++arg) {
/* process the buffer */
if (read_num_buf(NULL, argv[arg]) == NULL) {
fprintf(stderr, "%s: ouch\n", program);
exit(1);
}
/* factor the argument */
if (sscanf(argv[arg], "%ld", &val) == 1) {
pr_fact(val);
} else {
fprintf(stderr, "%s: ouch\n", program);
exit(1);
}
}
/* no args supplied, read numbers from stdin */
} else {
/*
* read asciii numbers from input
*/
while (read_num_buf(stdin, buf) != NULL) {
/* factor the argument */
if (sscanf(buf, "%ld", &val) == 1) {
pr_fact(val);
}
}
}
exit(0);
}
/*
* read_num_buf - read a number buffer from a stream
*
* Read a number on a line of the form:
*
* ^[ \t]*\([+-]?[0-9][0-9]\)*.*$
*
* where ? is a 1-or-0 operator and the number is within \( \).
*
* If does not match the above pattern, it is ignored and a new
* line is read. If the number is too large or small, we will
* print ouch and read a new line.
*
* We have to be very careful on how we check the magnitude of the
* input. We can not use numeric checks because of the need to
* check values against maximum numeric values.
*
* This routine will return a line containing a ascii number between
* NEG_SEMIBIG and SEMIBIG, or it will return NULL.
*
* If the stream is NULL then buf will be processed as if were
* a single line stream.
*
* returns:
* char * pointer to leading digit, + or -
* NULL EOF or error
*/
char *
read_num_buf(input, buf)
FILE *input; /* input stream or NULL */
char *buf; /* input buffer */
{
static char limit[MAX_LINE+1]; /* ascii value of SEMIBIG */
static int limit_len; /* digit count of limit */
static char neg_limit[MAX_LINE+1]; /* value of NEG_SEMIBIG */
static int neg_limit_len; /* digit count of neg_limit */
int len; /* digits in input (excluding +/-) */
char *s; /* line start marker */
char *d; /* first digit, skip +/- */
char *p; /* scan pointer */
char *z; /* zero scan pointer */
/* form the ascii value of SEMIBIG if needed */
if (!isascii(limit[0]) || !isdigit(limit[0])) {
sprintf(limit, "%ld", SEMIBIG);
limit_len = strlen(limit);
sprintf(neg_limit, "%ld", NEG_SEMIBIG);
neg_limit_len = strlen(neg_limit)-1; /* exclude - */
}
/*
* the search for a good line
*/
if (input != NULL && fgets(buf, MAX_LINE, input) == NULL) {
/* error or EOF */
return NULL;
}
do {
/* ignore leading whitespace */
for (s=buf; *s && s < buf+MAX_LINE; ++s) {
if (!isascii(*s) || !isspace(*s)) {
break;
}
}
/* skip over any leading + or - */
if (*s == '+' || *s == '-') {
d = s+1;
} else {
d = s;
}
/* note leading zeros */
for (z=d; *z && z < buf+MAX_LINE; ++z) {
if (*z != '0') {
break;
}
}
/* scan for the first non-digit */
for (p=d; *p && p < buf+MAX_LINE; ++p) {
if (!isascii(*p) || !isdigit(*p)) {
break;
}
}
/* ignore empty lines */
if (p == d) {
continue;
}
*p = '\0';
/* object if too many digits */
len = strlen(z);
len = (len<=0) ? 1 : len;
if (*s == '-') {
/* accept if digit count is below limit */
if (len < neg_limit_len) {
/* we have good input */
return s;
/* reject very large numbers */
} else if (len > neg_limit_len) {
fprintf(stderr, "%s: ouch\n", program);
exit(1);
/* carefully check against near limit numbers */
} else if (strcmp(z, neg_limit+1) > 0) {
fprintf(stderr, "%s: ouch\n", program);
exit(1);
}
/* number is near limit, but is under it */
return s;
} else {
/* accept if digit count is below limit */
if (len < limit_len) {
/* we have good input */
return s;
/* reject very large numbers */
} else if (len > limit_len) {
fprintf(stderr, "%s: ouch\n", program);
exit(1);
/* carefully check against near limit numbers */
} else if (strcmp(z, limit) > 0) {
fprintf(stderr, "%s: ouch\n", program);
exit(1);
}
/* number is near limit, but is under it */
return s;
}
} while (input != NULL && fgets(buf, MAX_LINE, input) != NULL);
/* error or EOF */
return NULL;
}
/*
* pr_fact - print the factors of a number
*
* If the number is 0 or 1, then print the number and return.
* If the number is < 0, print -1, negate the number and continue
* processing.
*
* Print the factors of the number, from the lowest to the highest.
* A factor will be printed numtiple times if it divides the value
* multiple times.
*
* Factors are printed with leading tabs.
*/
void
pr_fact(val)
long val; /* factor this value */
{
ubig *fact; /* the factor found */
/* firewall - catch 0 and 1 */
switch (val) {
case LONG_MIN:
/* avoid negation problems - assumes LONG_MIN is even XXX */
printf("%ld: -1 2", val);
val /= -2;
break;
case -1:
puts("-1: -1\n");
return;
case 0:
exit(0);
case 1:
puts("1: 1\n");
return;
default:
if (val < 0) {
val = -val;
printf("%ld: -1", val);
} else
printf("%ld:", val);
break;
}
fflush(stdout);
/*
* factor value
*/
fact = &prime[0];
while (val > 1) {
/* look for the smallest factor */
do {
if (val%(long)*fact == 0) {
break;
}
} while (++fact <= pr_limit);
/* watch for primes larger than the table */
if (fact > pr_limit) {
printf(" %ld\n", val);
return;
}
/* divide factor out until none are left */
do {
printf(" %ld", *fact);
val /= (long)*fact;
} while ((val % (long)*fact) == 0);
fflush(stdout);
++fact;
}
putchar('\n');
return;
}