82 lines
1.7 KiB
C
82 lines
1.7 KiB
C
/* factor.c - Factor integers
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*
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* Copyright 2014 Rob Landley <rob@landley.net>
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*
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* See https://man7.org/linux/man-pages/man1/factor.1.html
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*
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* -h and -x options come from https://man.netbsd.org/factor.6
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USE_FACTOR(NEWTOY(factor, "?hx", TOYFLAG_USR|TOYFLAG_BIN))
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config FACTOR
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bool "factor"
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default y
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help
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usage: factor NUMBER...
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Factor integers.
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-h Human readable: show repeated factors as x^n
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-x Hexadecimal output
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*/
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#define FOR_factor
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#include "toys.h"
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static void factor(char *s)
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{
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unsigned long long l, ll, lll;
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char *pat1 = FLAG(x) ? " %llx" : " %llu", *pat2 = FLAG(x) ? "^%x" : "^%u";
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for (;;) {
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char *err = s;
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int dash = 0, ii;
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while(isspace(*s)) s++;
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if (*s=='-') dash = *s++;
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if (!*s) return;
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errno = 0;
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l = strtoull(s, &s, 0);
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if (errno || (*s && !isspace(*s))) {
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error_msg("%s: not integer", err);
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while (*s && !isspace(*s)) s++;
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continue;
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}
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if (dash) xputc('-');
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printf(pat1+1, l);
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xputc(':');
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// Negative numbers have -1 as a factor
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if (dash) printf(" -1");
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// test 2 and odd numbers until square is > remainder or integer wrap.
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for (ll = 2;; ll += 1+(ll!=2)) {
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lll = ll*ll;
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if (lll>l || lll<ll) {
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if (l>1 || ll==2) printf(pat1, l);
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break;
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}
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for (ii = 0; !(l%ll); ii++) {
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if (!ii || !FLAG(h)) printf(pat1, ll);
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l /= ll;
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}
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if (ii>1 && FLAG(h)) printf(pat2, ii);
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}
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xputc('\n');
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}
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}
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void factor_main(void)
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{
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char *s = 0, **ss;
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size_t len = 0;
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if (toys.optc) for (ss = toys.optargs; *ss; ss++) factor(*ss);
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else for (;;) {
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if (-1 == getline(&s, &len, stdin)) break;
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factor(s);
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}
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}
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