[unix-history] / usr / src / games / factor / factor.c

/*
 * Copyright (c) 1989 The Regents of the University of California.
 * All rights reserved.
 *
 * This code is derived from software contributed to Berkeley by
 * Landon Curt Noll.
 *
 * %sccs.include.redist.c%
 */

#ifndef lint
char copyright[] =
"@(#) Copyright (c) 1989 The Regents of the University of California.\n\
 All rights reserved.\n";
#endif /* not lint */

#ifndef lint
static char sccsid[] = "@(#)factor.c	4.4 (Berkeley) %G%";
#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 <stdio.h>
#include <ctype.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 -2147483648:
		/* avoid negation problems */
		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");
		return;
	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);
		}
		fflush(stdout);
		break;
	}

	/*
	 * 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;
}
Commit	Line	Data
bc2e2efb KB	1	/*
	2	* Copyright (c) 1989 The Regents of the University of California.
	3	* All rights reserved.
	4	*
	5	* This code is derived from software contributed to Berkeley by
	6	* Landon Curt Noll.
	7	*
badc70cc	8	* %sccs.include.redist.c%
bc2e2efb KB	9	*/
bc2e2efb KB	10
6708b7e4	11	#ifndef lint
bc2e2efb KB	12	char copyright[] =
	13	"@(#) Copyright (c) 1989 The Regents of the University of California.\n\
	14	All rights reserved.\n";
	15	#endif /* not lint */
	16
	17	#ifndef lint
badc70cc	18	static char sccsid[] = "@(#)factor.c 4.4 (Berkeley) %G%";
bc2e2efb KB	19	#endif /* not lint */
	20
	21	/*
	22	* factor - factor a number into primes
	23	*
	24	* By: Landon Curt Noll chongo@toad.com, ...!{sun,tolsoft}!hoptoad!chongo
	25	*
	26	* chongo <for a good prime call: 391581 * 2^216193 - 1> /\oo/\
	27	*
	28	* usage:
	29	* factor [number] ...
	30	*
18a3e3ca	31	* The form of the output is:
bc2e2efb	32	*
18a3e3ca KB	33	* number: factor1 factor1 factor2 factor3 factor3 factor3 ...
	34	*
	35	* where factor1 < factor2 < factor3 < ...
	36	*
	37	* If no args are given, the list of numbers are read from stdin.
bc2e2efb KB	38	*/
	39
	40	#include <stdio.h>
	41	#include <ctype.h>
	42	#include "primes.h"
6708b7e4 SL	43
6708b7e4 SL	44	/*
bc2e2efb	45	* prime[i] is the (i-1)th prime.
6708b7e4	46	*
bc2e2efb KB	47	* We are able to sieve 2^32-1 because this byte table yields all primes
bc2e2efb KB	48	* up to 65537 and 65537^2 > 2^32-1.
6708b7e4	49	*/
bc2e2efb KB	50	extern ubig prime[];
	51	extern ubig pr_limit; / largest prime in the prime array */
	52
	53	#define MAX_LINE 255 /* max line allowed on stdin */
	54
	55	void pr_fact(); /* print factors of a value */
	56	long small_fact(); /* find smallest factor of a value */
	57	char read_num_buf(); / read a number buffer */
	58	char program; / name of this program */
6708b7e4 SL	59
6708b7e4 SL	60	main(argc, argv)
bc2e2efb KB	61	int argc; /* arg count */
bc2e2efb KB	62	char argv[]; / the args */
6708b7e4	63	{
bc2e2efb KB	64	int arg; /* which arg to factor */
	65	long val; /* the value to factor */
	66	char buf[MAX_LINE+1]; /* input buffer */
6708b7e4	67
bc2e2efb KB	68	/* parse args */
bc2e2efb KB	69	program = argv[0];
6708b7e4	70	if (argc >= 2) {
bc2e2efb KB	71
	72	/* factor each arg */
	73	for (arg=1; arg < argc; ++arg) {
	74
	75	/* process the buffer */
	76	if (read_num_buf(NULL, argv[arg]) == NULL) {
	77	fprintf(stderr, "%s: ouch\n", program);
	78	exit(1);
	79	}
	80
	81	/* factor the argument */
	82	if (sscanf(argv[arg], "%ld", &val) == 1) {
	83	pr_fact(val);
	84	} else {
	85	fprintf(stderr, "%s: ouch\n", program);
	86	exit(1);
	87	}
	88	}
	89
	90	/* no args supplied, read numbers from stdin */
6708b7e4	91	} else {
bc2e2efb KB	92	/*
	93	* read asciii numbers from input
	94	*/
	95	while (read_num_buf(stdin, buf) != NULL) {
	96
	97	/* factor the argument */
	98	if (sscanf(buf, "%ld", &val) == 1) {
	99	pr_fact(val);
	100	}
	101	}
6708b7e4	102	}
bc2e2efb	103	exit(0);
6708b7e4 SL	104	}
	105
	106	/*
bc2e2efb KB	107	* read_num_buf - read a number buffer from a stream
	108	*
	109	* Read a number on a line of the form:
	110	*
	111	* ^[ \t]\([+-]?[0-9][0-9]\).*$
	112	*
	113	* where ? is a 1-or-0 operator and the number is within \( \).
	114	*
	115	* If does not match the above pattern, it is ignored and a new
	116	* line is read. If the number is too large or small, we will
	117	* print ouch and read a new line.
	118	*
	119	* We have to be very careful on how we check the magnitude of the
	120	* input. We can not use numeric checks because of the need to
	121	* check values against maximum numeric values.
	122	*
	123	* This routine will return a line containing a ascii number between
	124	* NEG_SEMIBIG and SEMIBIG, or it will return NULL.
	125	*
	126	* If the stream is NULL then buf will be processed as if were
	127	* a single line stream.
	128	*
	129	* returns:
	130	* char * pointer to leading digit, + or -
	131	* NULL EOF or error
6708b7e4	132	*/
bc2e2efb KB	133	char *
	134	read_num_buf(input, buf)
	135	FILE input; / input stream or NULL */
	136	char buf; / input buffer */
6708b7e4	137	{
bc2e2efb KB	138	static char limit[MAX_LINE+1]; /* ascii value of SEMIBIG */
	139	static int limit_len; /* digit count of limit */
	140	static char neg_limit[MAX_LINE+1]; /* value of NEG_SEMIBIG */
	141	static int neg_limit_len; /* digit count of neg_limit */
	142	int len; /* digits in input (excluding +/-) */
	143	char s; / line start marker */
	144	char d; / first digit, skip +/- */
	145	char p; / scan pointer */
	146	char z; / zero scan pointer */
	147
	148	/* form the ascii value of SEMIBIG if needed */
	149	if (!isascii(limit[0]) \|\| !isdigit(limit[0])) {
	150	sprintf(limit, "%ld", SEMIBIG);
	151	limit_len = strlen(limit);
	152	sprintf(neg_limit, "%ld", NEG_SEMIBIG);
	153	neg_limit_len = strlen(neg_limit)-1; /* exclude - */
	154	}
	155
	156	/*
	157	* the search for a good line
	158	*/
	159	if (input != NULL && fgets(buf, MAX_LINE, input) == NULL) {
	160	/* error or EOF */
	161	return NULL;
6708b7e4	162	}
bc2e2efb KB	163	do {
	164
	165	/* ignore leading whitespace */
	166	for (s=buf; *s && s < buf+MAX_LINE; ++s) {
	167	if (!isascii(s) \|\| !isspace(s)) {
	168	break;
	169	}
	170	}
	171
	172	/* skip over any leading + or - */
	173	if (s == '+' \|\| s == '-') {
	174	d = s+1;
	175	} else {
	176	d = s;
	177	}
	178
	179	/* note leading zeros */
	180	for (z=d; *z && z < buf+MAX_LINE; ++z) {
	181	if (*z != '0') {
	182	break;
	183	}
	184	}
	185
	186	/* scan for the first non-digit */
	187	for (p=d; *p && p < buf+MAX_LINE; ++p) {
	188	if (!isascii(p) \|\| !isdigit(p)) {
	189	break;
	190	}
	191	}
	192
	193	/* ignore empty lines */
	194	if (p == d) {
	195	continue;
	196	}
	197	*p = '\0';
	198
	199	/* object if too many digits */
	200	len = strlen(z);
	201	len = (len<=0) ? 1 : len;
	202	if (*s == '-') {
	203	/* accept if digit count is below limit */
	204	if (len < neg_limit_len) {
	205	/* we have good input */
	206	return s;
	207
	208	/* reject very large numbers */
	209	} else if (len > neg_limit_len) {
	210	fprintf(stderr, "%s: ouch\n", program);
	211	exit(1);
	212
	213	/* carefully check against near limit numbers */
	214	} else if (strcmp(z, neg_limit+1) > 0) {
	215	fprintf(stderr, "%s: ouch\n", program);
	216	exit(1);
	217	}
	218	/* number is near limit, but is under it */
	219	return s;
	220
	221	} else {
	222	/* accept if digit count is below limit */
	223	if (len < limit_len) {
	224	/* we have good input */
	225	return s;
	226
227	/* reject very large numbers */
228	} else if (len > limit_len) {
229	fprintf(stderr, "%s: ouch\n", program);
230	exit(1);
231
232	/* carefully check against near limit numbers */
233	} else if (strcmp(z, limit) > 0) {
234	fprintf(stderr, "%s: ouch\n", program);
235	exit(1);
236	}
237	/* number is near limit, but is under it */
238	return s;
239	}
240	} while (input != NULL && fgets(buf, MAX_LINE, input) != NULL);
241
242	/* error or EOF */
243	return NULL;
6708b7e4 SL	244	}
6708b7e4 SL	245
bc2e2efb	246
6708b7e4	247	/*
bc2e2efb KB	248	* pr_fact - print the factors of a number
	249	*
	250	* If the number is 0 or 1, then print the number and return.
	251	* If the number is < 0, print -1, negate the number and continue
	252	* processing.
	253	*
	254	* Print the factors of the number, from the lowest to the highest.
	255	* A factor will be printed numtiple times if it divides the value
	256	* multiple times.
6708b7e4	257	*
bc2e2efb	258	* Factors are printed with leading tabs.
6708b7e4	259	*/
bc2e2efb KB	260	void
	261	pr_fact(val)
	262	long val; /* factor this value */
6708b7e4	263	{
bc2e2efb KB	264	ubig fact; / the factor found */
	265
	266	/* firewall - catch 0 and 1 */
	267	switch (val) {
	268	case -2147483648:
	269	/* avoid negation problems */
	270	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");
	271	return;
	272	case -1:
	273	puts("-1: -1\n");
	274	return;
	275	case 0:
	276	exit(0);
	277	case 1:
	278	puts("1: 1\n");
	279	return;
	280	default:
	281	if (val < 0) {
	282	val = -val;
	283	printf("%ld: -1", val);
	284	} else {
	285	printf("%ld:", val);
6708b7e4	286	}
bc2e2efb KB	287	fflush(stdout);
bc2e2efb KB	288	break;
6708b7e4 SL	289	}
6708b7e4 SL	290
bc2e2efb KB	291	/*
	292	* factor value
	293	*/
	294	fact = &prime[0];
	295	while (val > 1) {
6708b7e4	296
bc2e2efb KB	297	/* look for the smallest factor */
	298	do {
	299	if (val%(long)*fact == 0) {
	300	break;
6708b7e4	301	}
bc2e2efb	302	} while (++fact <= pr_limit);
6708b7e4	303
bc2e2efb KB	304	/* watch for primes larger than the table */
	305	if (fact > pr_limit) {
	306	printf(" %ld\n", val);
	307	return;
	308	}
6708b7e4	309
bc2e2efb KB	310	/* divide factor out until none are left */
	311	do {
	312	printf(" %ld", *fact);
	313	val /= (long)*fact;
	314	} while ((val % (long)*fact) == 0);
	315	fflush(stdout);
	316	++fact;
	317	}
	318	putchar('\n');
	319	return;
6708b7e4	320	}