/*      $NetBSD: primes.c,v 1.22 2018/02/03 15:40:29 christos Exp $     */

/*
* 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. 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.
*/

#include <sys/cdefs.h>
#ifndef lint
__COPYRIGHT("@(#) Copyright (c) 1989, 1993\
The Regents of the University of California.  All rights reserved.");
#endif /* not lint */

#ifndef lint
#if 0
static char sccsid[] = "@(#)primes.c    8.5 (Berkeley) 5/10/95";
#else
__RCSID("$NetBSD: primes.c,v 1.22 2018/02/03 15:40:29 christos Exp $");
#endif
#endif /* not lint */

/*
* primes - generate a table of primes between two values
*
* By Landon Curt Noll, http://www.isthe.com/chongo/index.html /\oo/\
*
* usage:
*      primes [-dh] [start [stop]]
*
*      Print primes >= start and < stop.  If stop is omitted,
*      the value SPSPMAX is assumed.  If start is
*      omitted, start is read from standard input.
*              -d: print difference to previous prime, e.g. 3 (1)
*              -h: print primes in hexadecimal
*
* validation check: there are 664579 primes between 0 and 10^7
*/

#include <ctype.h>
#include <err.h>
#include <errno.h>
#include <inttypes.h>
#include <limits.h>
#include <math.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>

#include "primes.h"

/*
* Eratosthenes sieve table
*
* We only sieve the odd numbers.  The base of our sieve windows are always
* odd.  If the base of table is 1, table[i] represents 2*i-1.  After the
* sieve, table[i] == 1 if and only if 2*i-1 is prime.
*
* We make TABSIZE large to reduce the overhead of inner loop setup.
*/
static char table[TABSIZE];      /* Eratosthenes sieve of odd numbers */

static int dflag, hflag;

static void primes(uint64_t, uint64_t);
static uint64_t read_num_buf(void);
static void usage(void) __dead;


int
main(int argc, char *argv[])
{
       uint64_t start;         /* where to start generating */
       uint64_t stop;          /* don't generate at or above this value */
       int ch;
       char *p;

       while ((ch = getopt(argc, argv, "dh")) != -1)
               switch (ch) {
               case 'd':
                       dflag++;
                       break;
               case 'h':
                       hflag++;
                       break;
               case '?':
               default:
                       usage();
               }
       argc -= optind;
       argv += optind;

       start = 0;
       stop = (uint64_t)(-1);

       /*
        * Convert low and high args.  Strtoumax(3) sets errno to
        * ERANGE if the number is too large, but, if there's
        * a leading minus sign it returns the negation of the
        * result of the conversion, which we'd rather disallow.
        */
       switch (argc) {
       case 2:
               /* Start and stop supplied on the command line. */
               if (argv[0][0] == '-' || argv[1][0] == '-')
                       errx(1, "negative numbers aren't permitted.");

               errno = 0;
               start = strtoumax(argv[0], &p, 0);
               if (errno)
                       err(1, "%s", argv[0]);
               if (*p != '\0')
                       errx(1, "%s: illegal numeric format.", argv[0]);

               errno = 0;
               stop = strtoumax(argv[1], &p, 0);
               if (errno)
                       err(1, "%s", argv[1]);
               if (*p != '\0')
                       errx(1, "%s: illegal numeric format.", argv[1]);
               break;
       case 1:
               /* Start on the command line. */
               if (argv[0][0] == '-')
                       errx(1, "negative numbers aren't permitted.");

               errno = 0;
               start = strtoumax(argv[0], &p, 0);
               if (errno)
                       err(1, "%s", argv[0]);
               if (*p != '\0')
                       errx(1, "%s: illegal numeric format.", argv[0]);
               break;
       case 0:
               start = read_num_buf();
               break;
       default:
               usage();
       }

       if (start > stop)
               errx(1, "start value must be less than stop value.");
       primes(start, stop);
       return (0);
}

/*
* read_num_buf --
*      This routine returns a number n, where 0 <= n && n <= ULONG_MAX.
*/
static uint64_t
read_num_buf(void)
{
       uint64_t val;
       char *p, buf[LINE_MAX];         /* > max number of digits. */

       for (;;) {
               if (fgets(buf, sizeof(buf), stdin) == NULL) {
                       if (ferror(stdin))
                               err(1, "stdin");
                       exit(0);
               }
               for (p = buf; isblank((unsigned char)*p); ++p);
               if (*p == '\n' || *p == '\0')
                       continue;
               if (*p == '-')
                       errx(1, "negative numbers aren't permitted.");
               errno = 0;
               val = strtoumax(buf, &p, 0);
               if (errno)
                       err(1, "%s", buf);
               if (*p != '\n')
                       errx(1, "%s: illegal numeric format.", buf);
               return (val);
       }
}

/*
* primes - sieve and print primes from start up to and but not including stop
*/
static void
primes(uint64_t start, uint64_t stop)
{
       char *q;                /* sieve spot */
       uint64_t factor;        /* index and factor */
       char *tab_lim;          /* the limit to sieve on the table */
       const uint64_t *p;      /* prime table pointer */
       uint64_t fact_lim;      /* highest prime for current block */
       uint64_t mod;           /* temp storage for mod */
       uint64_t prev = 0;

       /*
        * A number of systems can not convert double values into unsigned
        * longs when the values are larger than the largest signed value.
        * We don't have this problem, so we can go all the way to ULONG_MAX.
        */
       if (start < 3) {
               start = 2;
       }
       if (stop < 3) {
               stop = 2;
       }
       if (stop <= start) {
               return;
       }

       /*
        * be sure that the values are odd, or 2
        */
       if (start != 2 && (start&0x1) == 0) {
               ++start;
       }
       if (stop != 2 && (stop&0x1) == 0) {
               ++stop;
       }

       /*
        * quick list of primes <= pr_limit
        */
       if (start <= *pr_limit) {
               /* skip primes up to the start value */
               for (p = &prime[0], factor = prime[0];
                   factor < stop && p <= pr_limit; factor = *(++p)) {
                       if (factor >= start) {
                               printf(hflag ? "%" PRIx64 : "%" PRIu64, factor);
                               if (dflag) {
                                       printf(" (%" PRIu64 ")", factor - prev);
                               }
                               putchar('\n');
                       }
                       prev = factor;
               }
               /* return early if we are done */
               if (p <= pr_limit) {
                       return;
               }
               start = *pr_limit+2;
       }

       /*
        * we shall sieve a bytemap window, note primes and move the window
        * upward until we pass the stop point
        */
       while (start < stop) {
               /*
                * factor out 3, 5, 7, 11 and 13
                */
               /* initial pattern copy */
               factor = (start%(2*3*5*7*11*13))/2; /* starting copy spot */
               memcpy(table, &pattern[factor], pattern_size-factor);
               /* main block pattern copies */
               for (fact_lim=pattern_size-factor;
                   fact_lim+pattern_size<=TABSIZE; fact_lim+=pattern_size) {
                       memcpy(&table[fact_lim], pattern, pattern_size);
               }
               /* final block pattern copy */
               memcpy(&table[fact_lim], pattern, TABSIZE-fact_lim);

               /*
                * sieve for primes 17 and higher
                */
               /* note highest useful factor and sieve spot */
               if (stop-start > TABSIZE+TABSIZE) {
                       tab_lim = &table[TABSIZE]; /* sieve it all */
                       fact_lim = sqrt(start+1.0+TABSIZE+TABSIZE);
               } else {
                       tab_lim = &table[(stop-start)/2]; /* partial sieve */
                       fact_lim = sqrt(stop+1.0);
               }
               /* sieve for factors >= 17 */
               factor = 17;    /* 17 is first prime to use */
               p = &prime[7];  /* 19 is next prime, pi(19)=7 */
               do {
                       /* determine the factor's initial sieve point */
                       mod = start%factor;
                       if (mod & 0x1) {
                               q = &table[(factor-mod)/2];
                       } else {
                               q = &table[mod ? factor-(mod/2) : 0];
                       }
                       /* sieve for our current factor */
                       for ( ; q < tab_lim; q += factor) {
                               *q = '\0'; /* sieve out a spot */
                       }
                       factor = *p++;
               } while (factor <= fact_lim);

               /*
                * print generated primes
                */
               for (q = table; q < tab_lim; ++q, start+=2) {
                       if (*q) {
                               if (start > SIEVEMAX) {
                                       if (!isprime(start))
                                               continue;
                               }
                               printf(hflag ? "%" PRIx64 : "%" PRIu64, start);
                               if (dflag && (prev || (start <= *pr_limit))) {
                                       printf(" (%" PRIu64 ")", start - prev);
                               }
                               putchar('\n');
                               prev = start;
                       }
               }
       }
}

static void
usage(void)
{
       (void)fprintf(stderr, "usage: primes [-dh] [start [stop]]\n");
       exit(1);
}

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