348 lines
8.9 KiB
C
348 lines
8.9 KiB
C
/*
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* Copyright (c) 1989 The Regents of the University of California.
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* All rights reserved.
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*
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* This code is derived from software contributed to Berkeley by
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* Landon Curt Noll.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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* 3. All advertising materials mentioning features or use of this software
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* must display the following acknowledgement:
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* This product includes software developed by the University of
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* California, Berkeley and its contributors.
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* 4. Neither the name of the University nor the names of its contributors
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* may be used to endorse or promote products derived from this software
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* without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
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* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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* ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
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* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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* SUCH DAMAGE.
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*/
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#ifndef lint
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char copyright[] =
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"@(#) Copyright (c) 1989 The Regents of the University of California.\n\
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All rights reserved.\n";
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#endif /* not lint */
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#ifndef lint
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/*static char sccsid[] = "from: @(#)factor.c 4.4 (Berkeley) 6/1/90";*/
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static char rcsid[] = "$Id: factor.c,v 1.2 1993/08/01 18:54:58 mycroft Exp $";
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#endif /* not lint */
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/*
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* factor - factor a number into primes
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*
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* By: Landon Curt Noll chongo@toad.com, ...!{sun,tolsoft}!hoptoad!chongo
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*
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* chongo <for a good prime call: 391581 * 2^216193 - 1> /\oo/\
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*
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* usage:
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* factor [number] ...
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*
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* The form of the output is:
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*
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* number: factor1 factor1 factor2 factor3 factor3 factor3 ...
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*
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* where factor1 < factor2 < factor3 < ...
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*
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* If no args are given, the list of numbers are read from stdin.
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*/
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#include <stdio.h>
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#include <ctype.h>
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#include "primes.h"
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/*
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* prime[i] is the (i-1)th prime.
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*
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* We are able to sieve 2^32-1 because this byte table yields all primes
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* up to 65537 and 65537^2 > 2^32-1.
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*/
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extern ubig prime[];
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extern ubig *pr_limit; /* largest prime in the prime array */
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#define MAX_LINE 255 /* max line allowed on stdin */
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void pr_fact(); /* print factors of a value */
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long small_fact(); /* find smallest factor of a value */
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char *read_num_buf(); /* read a number buffer */
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char *program; /* name of this program */
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main(argc, argv)
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int argc; /* arg count */
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char *argv[]; /* the args */
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{
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int arg; /* which arg to factor */
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long val; /* the value to factor */
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char buf[MAX_LINE+1]; /* input buffer */
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/* parse args */
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program = argv[0];
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if (argc >= 2) {
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/* factor each arg */
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for (arg=1; arg < argc; ++arg) {
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/* process the buffer */
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if (read_num_buf(NULL, argv[arg]) == NULL) {
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fprintf(stderr, "%s: ouch\n", program);
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exit(1);
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}
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/* factor the argument */
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if (sscanf(argv[arg], "%ld", &val) == 1) {
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pr_fact(val);
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} else {
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fprintf(stderr, "%s: ouch\n", program);
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exit(1);
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}
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}
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/* no args supplied, read numbers from stdin */
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} else {
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/*
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* read asciii numbers from input
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*/
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while (read_num_buf(stdin, buf) != NULL) {
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/* factor the argument */
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if (sscanf(buf, "%ld", &val) == 1) {
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pr_fact(val);
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}
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}
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}
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exit(0);
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}
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/*
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* read_num_buf - read a number buffer from a stream
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*
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* Read a number on a line of the form:
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*
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* ^[ \t]*\([+-]?[0-9][0-9]\)*.*$
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*
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* where ? is a 1-or-0 operator and the number is within \( \).
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*
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* If does not match the above pattern, it is ignored and a new
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* line is read. If the number is too large or small, we will
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* print ouch and read a new line.
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*
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* We have to be very careful on how we check the magnitude of the
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* input. We can not use numeric checks because of the need to
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* check values against maximum numeric values.
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*
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* This routine will return a line containing a ascii number between
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* NEG_SEMIBIG and SEMIBIG, or it will return NULL.
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*
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* If the stream is NULL then buf will be processed as if were
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* a single line stream.
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*
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* returns:
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* char * pointer to leading digit, + or -
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* NULL EOF or error
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*/
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char *
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read_num_buf(input, buf)
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FILE *input; /* input stream or NULL */
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char *buf; /* input buffer */
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{
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static char limit[MAX_LINE+1]; /* ascii value of SEMIBIG */
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static int limit_len; /* digit count of limit */
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static char neg_limit[MAX_LINE+1]; /* value of NEG_SEMIBIG */
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static int neg_limit_len; /* digit count of neg_limit */
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int len; /* digits in input (excluding +/-) */
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char *s; /* line start marker */
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char *d; /* first digit, skip +/- */
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char *p; /* scan pointer */
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char *z; /* zero scan pointer */
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/* form the ascii value of SEMIBIG if needed */
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if (!isascii(limit[0]) || !isdigit(limit[0])) {
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sprintf(limit, "%ld", SEMIBIG);
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limit_len = strlen(limit);
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sprintf(neg_limit, "%ld", NEG_SEMIBIG);
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neg_limit_len = strlen(neg_limit)-1; /* exclude - */
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}
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/*
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* the search for a good line
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*/
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if (input != NULL && fgets(buf, MAX_LINE, input) == NULL) {
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/* error or EOF */
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return NULL;
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}
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do {
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/* ignore leading whitespace */
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for (s=buf; *s && s < buf+MAX_LINE; ++s) {
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if (!isascii(*s) || !isspace(*s)) {
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break;
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}
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}
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/* skip over any leading + or - */
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if (*s == '+' || *s == '-') {
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d = s+1;
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} else {
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d = s;
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}
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/* note leading zeros */
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for (z=d; *z && z < buf+MAX_LINE; ++z) {
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if (*z != '0') {
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break;
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}
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}
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/* scan for the first non-digit */
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for (p=d; *p && p < buf+MAX_LINE; ++p) {
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if (!isascii(*p) || !isdigit(*p)) {
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break;
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}
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}
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/* ignore empty lines */
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if (p == d) {
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continue;
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}
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*p = '\0';
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/* object if too many digits */
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len = strlen(z);
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len = (len<=0) ? 1 : len;
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if (*s == '-') {
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/* accept if digit count is below limit */
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if (len < neg_limit_len) {
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/* we have good input */
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return s;
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/* reject very large numbers */
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} else if (len > neg_limit_len) {
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fprintf(stderr, "%s: ouch\n", program);
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exit(1);
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/* carefully check against near limit numbers */
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} else if (strcmp(z, neg_limit+1) > 0) {
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fprintf(stderr, "%s: ouch\n", program);
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exit(1);
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}
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/* number is near limit, but is under it */
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return s;
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} else {
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/* accept if digit count is below limit */
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if (len < limit_len) {
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/* we have good input */
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return s;
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/* reject very large numbers */
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} else if (len > limit_len) {
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fprintf(stderr, "%s: ouch\n", program);
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exit(1);
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/* carefully check against near limit numbers */
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} else if (strcmp(z, limit) > 0) {
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fprintf(stderr, "%s: ouch\n", program);
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exit(1);
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}
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/* number is near limit, but is under it */
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return s;
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}
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} while (input != NULL && fgets(buf, MAX_LINE, input) != NULL);
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/* error or EOF */
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return NULL;
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}
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/*
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* pr_fact - print the factors of a number
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*
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* If the number is 0 or 1, then print the number and return.
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* If the number is < 0, print -1, negate the number and continue
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* processing.
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*
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* Print the factors of the number, from the lowest to the highest.
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* A factor will be printed numtiple times if it divides the value
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* multiple times.
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*
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* Factors are printed with leading tabs.
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*/
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void
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pr_fact(val)
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long val; /* factor this value */
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{
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ubig *fact; /* the factor found */
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/* firewall - catch 0 and 1 */
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switch (val) {
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case -2147483648:
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/* avoid negation problems */
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puts("-2147483648: -1 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2\n");
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return;
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case -1:
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puts("-1: -1\n");
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return;
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case 0:
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exit(0);
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case 1:
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puts("1: 1\n");
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return;
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default:
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if (val < 0) {
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val = -val;
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printf("%ld: -1", val);
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} else {
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printf("%ld:", val);
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}
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fflush(stdout);
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break;
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}
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/*
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* factor value
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*/
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fact = &prime[0];
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while (val > 1) {
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/* look for the smallest factor */
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do {
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if (val%(long)*fact == 0) {
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break;
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}
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} while (++fact <= pr_limit);
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/* watch for primes larger than the table */
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if (fact > pr_limit) {
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printf(" %ld\n", val);
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return;
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}
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/* divide factor out until none are left */
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do {
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printf(" %ld", *fact);
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val /= (long)*fact;
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} while ((val % (long)*fact) == 0);
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fflush(stdout);
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++fact;
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}
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putchar('\n');
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return;
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}
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