/* @(#) $Revision: 1.7 $ */
/* @(#) RCS control in //prime.corp/usr/local/src/cmd/prime/src/mkprimetbl.c */
/*
 * mkprimetbl - make a prime table
 *
 * usage:
 *	mkprimetbl name < primelist
 *
 *	name		form name.c and name.h
 *	primelist	primes in decimal ASCII, one per line
 *			(or pipe from the primes program) ignoring
 *			primes < 5 and the last prime is used only
 *			to set the value of NEXT_PRIME_DIFF
 *
 * This method works for primes < 436273291.  All primes < 436273291
 * differ by gaps <= 250 which can be represented in a single byte.
 * The next prime after 436273009 is 436273291 which represents a
 * gap of 282.
 */
/*
 *
 * Copyright (C) 1997 Landon Curt Noll, all rights reserved.
 *
 * Permission to use, copy, modify, and distribute this software and
 * its documentation for any purpose is hereby granted, provided that
 * the above copyright, this permission notice, and the disclaimer
 * below appear in all of the following:
 *
 *         * supporting documentation
 *         * source copies
 *         * source works derived from this source
 *
 * THE COPYRIGHT HOLDERS DISCLAIM ALL WARRANTIES WITH REGARD TO THIS SOFTWARE,
 * INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS, IN NO
 * EVENT SHALL THE COPYRIGHT HOLDERS BE LIABLE FOR ANY SPECIAL, INDIRECT OR
 * CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF
 * USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR
 * OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR
 * PERFORMANCE OF THIS SOFTWARE.
 *
 * Landon Curt Noll <chongo was here> /\oo/\
 *
 * chongo@{toad,sgi}.com		Share and Enjoy!
 */


#include <stdio.h>

#define MAXLINE 16	/* max differences per line */

extern int errno;	/* last error */

char *program;		/* our name */


main(argc, argv)
    int argc;		/* arg count */
    char *argv[];	/* the args */
{
    char *name;		/* base file name */
    char nextbuf[BUFSIZ+1];	/* input buffer */
    char buf[BUFSIZ+1];	/* full filename and current buffer */
    FILE *c;		/* name.c file */
    FILE *h;		/* name.h file */
    long prev;		/* previous prime */
    long this;		/* this prime */
    long next;		/* next prime */
    long cnt;		/* entries in prime_diff */
    long linecnt;	/* numbre of entries for the given line */

    /*
     * parse args
     */
    program = argv[0];
    if (argc != 2) {
	fprintf(stderr, "usage: %s name < primelist\n", program);
	exit(1);
    }
    name = argv[1];
    if (strlen(name) >= BUFSIZ-1) {
	fprintf(stderr, "%s: name is too long\n", program);
	exit(2);
    }

    /*
     * setup the name.c file
     */
    buf[BUFSIZ] = '\0';
    sprintf(buf, "%s.c", name);
    c = fopen(buf, "w");
    if (c == NULL) {
	fprintf(stderr, "%s: unable to open %s\n", program, buf);
	perror(program);
	exit(3);
    }
    fputs("/* DO NOT EDIT -- created by mkprimetbl */\n", c);
    fputc('\n', c);
    fprintf(c, "#include \"%s.h\"\n", name);
    fputc('\n', c);
    fputs("/*\n", c);
    fputs(" * odd prime difference table\n", c);
    fputs(" *\n", c);
    fputs(" * Starting with 3, the first table entry says how much to\n", c);
    fputs(" * add to it in order to reach the next prime\n", c);
    fputs(" *\n", c);
    fputs(" * The final entry is 1.\n", c);
    fputs(" */\n", c);
    fputs("unsigned char const prime_diff[PRIME_DIFF_CNT+1] = {", c);

    /*
     * read lines until we get a prime > 2
     */
    prev = 0;
    while (fgets(buf, BUFSIZ, stdin) != NULL) {

	/* convert to integer */
	errno = 0;
	prev = strtol(buf, (char **)NULL, 0);
	if (errno != 0) {
	    fprintf(stderr, "%s: bad strtol of <%s>\n", program, buf);
	    perror(program);
	    exit(4);
	}

	/* stop if value > 2 */
	if (prev >= 3) {
	    break;
	}
    }
    if (prev < 3) {
	fprintf(stderr, "%s: input must contain at least 2 primes > 2\n",
	  program);
	exit(5);
    }

    /*
     * read the 'this' prime
     */
    if (fgets(buf, BUFSIZ, stdin) == NULL) {
	fprintf(stderr, "%s: input must have at least 2 primes > 2\n",
	  program);
	exit(6);
    }
    /* convert to integer */
    errno = 0;
    this = strtol(buf, (char **)NULL, 0);
    if (errno != 0) {
	fprintf(stderr, "%s: bad strtol of <%s>\n", program, buf);
	perror(program);
	exit(7);
    }

    /*
     * read the primes from stdin
     */
    cnt = 0;
    linecnt = MAXLINE;
    /* read the next prime -- but don't use it yet */
    while (fgets(buf, BUFSIZ, stdin) != NULL) {

	/* object if even */
	if ((this&0x1) == 0) {
	    fprintf(stderr, "%s: input value %d >=5 is even, cannot be prime\n",
	      program, this);
	    exit(8);
	}

	/* object if < prev+2 value */
	if (this < prev+2) {
	    fprintf(stderr, "%s: input value %d < prev value %d+2\n",
	      program, this, prev);
	    exit(9);
	}

	/* firewall */
	if (this-prev >= 256) {
	    /* cannot represent this gap */
	    break;
	}

	/* print this difference */
	if (linecnt >= MAXLINE) {
	     fprintf(c, "\n    %3d,", this-prev);
	     linecnt = 1;
	} else {
	     fprintf(c, "%3d,", this-prev);
	     ++linecnt;
	}
	++cnt;

	/* prep for the next value */
	errno = 0;
	next = strtol(buf, (char **)NULL, 0);
	if (errno != 0) {
	    fprintf(stderr, "%s: bad strtol of <%s>\n", program, buf);
	    perror(program);
	    exit(10);
	}
	prev = this;
	this = next;
    }

    /*
     * finish the name.c file
     */
    fputs("  1\n", c);
    fputs("};", c);
    fputc('\n', c);
    fprintf(c, "/* difference for odd primes <= %d */\n", prev);
    fputs("/* table sentinal value is 1 */\n", c);
    fprintf(c, "/* first prime beyond table is %d */\n", this);
    fclose(c);

    /*
     * form the name.h file
     */
    sprintf(buf, "%s.h", name);
    h = fopen(buf, "w");
    if (h == NULL) {
	fprintf(stderr, "%s: unable to open %s\n", program, buf);
	perror(program);
	exit(11);
    }
    fputs("/* DO NOT EDIT -- created by mkprimetbl */\n", h);
    fputc('\n', h);
    fprintf(h, "/* difference for odd primes <= %d */\n", prev);
    fputs("/* table sentinal value is 1 */\n", h);
    fprintf(h, "/* first prime beyond table is %d */\n", this);
    fputc('\n', h);
    fprintf(h, "#define PRIME_DIFF_CNT %d\n", cnt);
    fprintf(h, "#define LAST_PRIME_DIFF %d\n", prev);
    fprintf(h, "#define NEXT_PRIME_DIFF %d\n", this);
    fputc('\n', h);
    fputs("#if !defined(NO_EXTERNS)\n", h);
    fputs("extern unsigned char const prime_diff[];\n", h);
    fputs("#endif /* !NO_EXTERNS */\n", h);
    fclose(h);

    /*
     * all done
     */
    exit(0);
}