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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% |
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9 | */ |
10 | ||
6708b7e4 | 11 | #ifndef lint |
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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%"; |
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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. | |
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38 | */ |
39 | ||
40 | #include <stdio.h> | |
41 | #include <ctype.h> | |
42 | #include "primes.h" | |
6708b7e4 SL |
43 | |
44 | /* | |
bc2e2efb | 45 | * prime[i] is the (i-1)th prime. |
6708b7e4 | 46 | * |
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47 | * We are able to sieve 2^32-1 because this byte table yields all primes |
48 | * up to 65537 and 65537^2 > 2^32-1. | |
6708b7e4 | 49 | */ |
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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 | |
60 | main(argc, argv) | |
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61 | int argc; /* arg count */ |
62 | char *argv[]; /* the args */ | |
6708b7e4 | 63 | { |
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64 | int arg; /* which arg to factor */ |
65 | long val; /* the value to factor */ | |
66 | char buf[MAX_LINE+1]; /* input buffer */ | |
6708b7e4 | 67 | |
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68 | /* parse args */ |
69 | program = argv[0]; | |
6708b7e4 | 70 | if (argc >= 2) { |
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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 { |
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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 | /* | |
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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 | */ |
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133 | char * |
134 | read_num_buf(input, buf) | |
135 | FILE *input; /* input stream or NULL */ | |
136 | char *buf; /* input buffer */ | |
6708b7e4 | 137 | { |
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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 | } |
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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 | } |
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 | */ |
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260 | void |
261 | pr_fact(val) | |
262 | long val; /* factor this value */ | |
6708b7e4 | 263 | { |
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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 | } |
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287 | fflush(stdout); |
288 | break; | |
6708b7e4 SL |
289 | } |
290 | ||
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291 | /* |
292 | * factor value | |
293 | */ | |
294 | fact = &prime[0]; | |
295 | while (val > 1) { | |
6708b7e4 | 296 | |
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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 | |
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304 | /* watch for primes larger than the table */ |
305 | if (fact > pr_limit) { | |
306 | printf(" %ld\n", val); | |
307 | return; | |
308 | } | |
6708b7e4 | 309 | |
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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 | } |