longbits.c

/*
 * longbits - Determine the number if bits in a char, short, int or long
 *
 * Copyright (C) 1999-2007,2014,2021,2023  Landon Curt Noll
 *
 * Calc is open software; you can redistribute it and/or modify it under
 * the terms of the version 2.1 of the GNU Lesser General Public License
 * as published by the Free Software Foundation.
 *
 * Calc is distributed in the hope that it will be useful, but WITHOUT
 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
 * or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU Lesser General
 * Public License for more details.
 *
 * A copy of version 2.1 of the GNU Lesser General Public License is
 * distributed with calc under the filename COPYING-LGPL.  You should have
 * received a copy with calc; if not, write to Free Software Foundation, Inc.
 * 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
 *
 * Under source code control:   1994/03/18 03:06:18
 * File existed as early as:    1994
 *
 * chongo <was here> /\oo/\     http://www.isthe.com/chongo/
 * Share and enjoy!  :-)        http://www.isthe.com/chongo/tech/comp/calc/
 */

/*
 * usage:
 *      longbits [long_bit_size]
 *
 *      long_bit_size   force size of long (must be 32 or 64)
 *
 * NOTE: If long_bit_size arg is empty (0 chars long) or it begins with
 *       a whitespace character, it will be ignored and no forcing will
 *       be done.
 *
 * Not all (in fact very few) C pre-processors can do:
 *
 *      #if sizeof(long) == 8
 *
 * so we have to form LONG_BITS ahead of time.
 *
 * This prog outputs several defines and typedefs:
 *
 *      LONG_BITS
 *              Number of bits in a long.
 *
 *      PTR_LEN
 *              Length of a pointer in bytes.  We use void * as a generic pointer.
 *
 *      PTR_BITS
 *              Length of a pointer in bits.  We use void * as a generic pointer.
 *
 *      USB8    unsigned 8 bit value
 *      SB8     signed 8 bit value
 *
 *      USB16   unsigned 16 bit value
 *      SB16    signed 16 bit value
 *
 *      USB32   unsigned 32 bit value
 *      SB32    signed 32 bit value
 *
 *      HAVE_B64
 *              defined ==> OK to use USB64 (unsigned 64 bit value)
 *                                and SB64 (signed 64 bit value)
 *              undefined ==> do not use USB64 nor SB64
 *
 *      BOOL_B64
 *              If HAVE_B64 undefined ==> false
 *              If HAVE_B64 defined ==> true
 *
 *      USB64   unsigned 64 bit value if HAVE_B64 is defined
 *      SB64    signed 64 bit value if HAVE_B64 is defined
 *
 *      L(x)    form a 33 to 64 bit signed constant
 *      U(x)    form a 33 to 64 bit unsigned constant
 *
 * We hide the comments within strings to avoid complaints from some snitty
 * compilers.  We also hide 3 X's which is the calc symbol for "something bogus
 * this way comes".  In such error cases, we add -=*#*=- to force a syntax
 * error in the resulting .h file.
 *
 * We will exit 0 if all is well, non-zero with an error to stderr otherwise.
 */


#include <stdio.h>
#include <ctype.h>

#include "have_unistd.h"
#if defined(HAVE_UNISTD_H)
#include <unistd.h>
#endif

#include "have_stdlib.h"
#ifdef HAVE_STDLIB_H
# include <stdlib.h>
#endif

#include "charbit.h"


#include "banned.h"     /* include after system header <> includes */


char *program;          /* our name */

int
main(int argc, char **argv)
{
        int exitcode = 0;       /* how we will exit */
        size_t long_bits = 0;   /* bit length of a long */
        int forced_size = 0;    /* 1 => size of long was forced via arg */
        char value;             /* signed or maybe unsigned character */

        /*
         * parse args
         */
        program = argv[0];
        switch (argc) {
        case 1:
                long_bits = sizeof(long)*8;
                break;
        case 2:
                /* ignore empty or leading space args */
                if (argv[1][0] == '\0' ||
                    (isascii((int)argv[1][0]) && isspace((int)argv[1][0]))) {
                        long_bits = sizeof(long)*CALC_CHARBIT;
                /* process the forced size arg */
                } else {
                        forced_size = 1;
                        long_bits = atoi(argv[1]);
                        if (long_bits != 32 && long_bits != 64) {
                                fprintf(stderr,
                                    "usage: %s [32 or 64]\n", program);
                                exit(1);
                        }
                }
                break;
        default:
                fprintf(stderr, "usage: %s [32 or 64]\n", program);
                exit(2);
        }

        /*
         * report size of a long
         */
        printf("#undef LONG_BITS\n");
        printf("#define LONG_BITS %ld\t\t/%s/\n",
          (long int)long_bits, "* bit length of a long *");
        putchar('\n');

        /*
         * report size of a pointer
         *
         * We use "void *" as the size of a generic pointer.
         */
        printf("#undef PTR_LEN\n");
#if MAJOR_VER < 3
        printf("#define PTR_LEN %ld\t\t/%s/\n",
          (long int)sizeof(void *), "* length of a pointer *");
#else /* MAJOR_VER < 3 */
        printf("#define PTR_LEN UINTPTR_WIDTH\t\t/%s/\n", "* length of a pointer *");
#endif /* MAJOR_VER < 3 */
        printf("#undef PTR_BITS\n");
        printf("#define PTR_BITS %ld\t\t/%s/\n",
          (long int)sizeof(void *)*CALC_CHARBIT, "* bit length of a pointer *");
        putchar('\n');

        /*
         * If we are forcing the size of a long, then do not check
         * sizes of other values but instead assume that the user
         * knows what they are doing.
         */
        if (forced_size) {

                /*
                 * note that the size was forced
                 */
                printf("/%s/\n\n", "* size of long was forced *");

                /*
                 * forced forming of USB8, SB8, USB16 and SB16
                 */
                printf("typedef unsigned char USB8;\t/%s/\n",
                    "* unsigned 8 bits *");
                printf("typedef signed char SB8;\t/%s/\n\n",
                    "* signed 8 bits *");

                printf("typedef unsigned short USB16;\t/%s/\n",
                    "* unsigned 16 bits *");
                printf("typedef short SB16;\t\t/%s/\n\n",
                    "* signed 16 bits *");

                /*
                 * forced forming of USB32 and SB32
                 */
                if (long_bits == 32) {
                        /* forced 32 bit long mode assumptions */
                        printf("typedef unsigned long USB32;\t/%s/\n",
                            "* unsigned 32 bits *");
                        printf("typedef long SB32;\t\t/%s/\n\n",
                            "* signed 32 bits *");
                } else {
                        /* forced 64 bit long mode assumptions */
                        printf("typedef unsigned int USB32;\t/%s/\n",
                            "* unsigned 32 bits *");
                        printf("typedef int SB32;\t\t/%s/\n\n",
                            "* signed 32 bits *");
                }

                /*
                 * forced forming of HAVE_B64, USB64, SB64, U(x) and L(x)
                 */
                printf("#undef HAVE_B64\n");
                printf("#define HAVE_B64\t\t/%s/\n",
                  "* have USB64 and SB64 types *");
                printf("typedef unsigned long long USB64;\t/%s/\n",
                  "* unsigned 64 bits *");
                printf("typedef long long SB64;\t\t/%s/\n",
                  "* signed 64 bits *");
                putchar('\n');
                printf("/%s/\n","* how to form 64 bit constants *");
#if defined(FORCE_STDC) || (defined(__STDC__) && __STDC__ != 0) || \
    defined(__cplusplus)
                printf("#define U(x) x ## ULL\n");
                printf("#define L(x) x ## LL\n");
#else
                printf("#define U(x) ((unsigned long long)x)\n");
                printf("#define L(x) ((long long)x)\n");
#endif

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

        /*
         * look for 8 bit values
         */
        value = (char)-1;
        if (sizeof(char) != 1) {
                fprintf(stderr,
                  "%s: OUCH!!! - char is not a single byte!\n", program);
                fprintf(stderr,
                  "%s: fix the USB8 typedef by hand\n", program);
                printf("typedef unsigned char USB8;\t/* XX%s/ -=*#*=-\n",
                  "X - should be 8 unsigned bits but is not *");
                if (value < 1) {
                        printf("typedef char SB8;\t\t/* XX%s/ -=*#*=-\n",
                          "X - should be 8 signed bits but is not *");
                } else {
                        printf("typedef signed char SB8;\t\t/* XX%s/ -=*#*=-\n",
                          "X - should be 8 signed bits but is not *");
                }
                exitcode = 3;
        } else {
                printf("typedef unsigned char USB8;\t/%s/\n",
                  "* unsigned 8 bits *");
                if (value < 1) {
                        printf("typedef char SB8;\t\t/%s/\n",
                          "* signed 8 bits *");
                } else {
                        printf("typedef signed char SB8;\t\t/%s/\n",
                          "* signed 8 bits *");
                }
        }
        putchar('\n');

        /*
         * look for 16 bit values
         */
        if (sizeof(short) != 2) {
                fprintf(stderr,
                  "%s: OUCH!!! - short is not a 2 bytes!\n", program);
                fprintf(stderr,
                  "%s: fix the USB16 typedef by hand\n", program);
                printf("typedef unsigned short USB16;\t/* XX%s/ -=*#*=-\n",
                  "X - should be 16 unsigned bits but is not *");
                printf("typedef signed char SB16;\t/* XX%s/ -=*#*=-\n",
                  "X - should be 16 signed bits but is not *");
                exitcode = 4;
        } else {
                printf("typedef unsigned short USB16;\t/%s/\n",
                  "* unsigned 16 bits *");
                printf("typedef short SB16;\t\t/%s/\n",
                  "* signed 16 bits *");
        }
        putchar('\n');

        /*
         * look for 32 bit values
         */
        if (sizeof(long) == 4) {
                printf("typedef unsigned long USB32;\t/%s/\n",
                  "* unsigned 32 bits *");
                printf("typedef long SB32;\t\t/%s/\n",
                  "* signed 32 bits *");
        } else if (sizeof(int) == 4) {
                printf("typedef unsigned int USB32;\t/%s/\n",
                  "* unsigned 32 bits *");
                printf("typedef int SB32;\t\t/%s/\n",
                  "* signed 32 bits *");
        } else {
                fprintf(stderr,
                  "%s: OUCH!!! - neither int nor long are 4 bytes!\n", program);
                printf("typedef unsigned int USB32;\t/* XX%s/ -=*#*=-\n",
                  "X - should be 32 unsigned bits but is not *");
                printf("typedef signed int SB32;\t/* XX%s/ -=*#*=-\n",
                  "X - should be 32 signed bits but is not *");
                exitcode = 5;
        }
        putchar('\n');

        /*
         * look for 64 bit values
         */
        if (sizeof(long) == 8) {
                printf("#undef HAVE_B64\n");
                printf("#define HAVE_B64\t\t/%s/\n",
                  "* have USB64 and SB64 types *");
                printf("typedef unsigned long USB64;\t/%s/\n",
                  "* unsigned 64 bits *");
                printf("typedef long SB64;\t\t/%s/\n",
                  "* signed 64 bits *");
                putchar('\n');
                printf("/%s/\n","* how to form 64 bit constants *");
#if defined(FORCE_STDC) || (defined(__STDC__) && __STDC__ != 0) || \
    defined(__cplusplus)
                printf("#define U(x) x ## UL\n");
                printf("#define L(x) x ## L\n");
#else
                printf("#define U(x) ((unsigned long)x)\n");
                printf("#define L(x) ((long)x)\n");
#endif
        } else {
                printf("#undef HAVE_B64\n");
                printf("#define HAVE_B64\t\t/%s/\n",
                  "* have USB64 and SB64 types *");
                printf("typedef unsigned long long USB64;\t/%s/\n",
                  "* unsigned 64 bits *");
                printf("typedef long long SB64;\t\t/%s/\n",
                  "* signed 64 bits *");
                putchar('\n');
                printf("/%s/\n","* how to form 64 bit constants *");
#if defined(FORCE_STDC) || (defined(__STDC__) && __STDC__ != 0) || \
    defined(__cplusplus)
                printf("#define U(x) x ## ULL\n");
                printf("#define L(x) x ## LL\n");
#else
                printf("#define U(x) ((unsigned long long)x)\n");
                printf("#define L(x) ((long long)x)\n");
#endif
        }

        /* all done */
        /* exit(exitcode); */
        return exitcode;
}