source: trunk/essentials/sys-apps/gawk/missing_d/strtoul.c

/*
 * Very simple implementation of strtoul() for gawk,
 * for old systems.  Descriptive prose from the Linux man page.
 *
 * May 2004
 */

/* #define TEST 1 */

#ifdef TEST
#include <stdio.h>
#include <stdlib.h>
#include <ctype.h>
#include <string.h>
#include <errno.h>
#include <limits.h>
#define TRUE 1
#define FALSE 0
#define strtoul mystrtoul
#endif

#ifndef ULONG_MAX
#define ULONG_MAX (~ 0UL)
#endif

unsigned long int
strtoul(nptr, endptr, base)
const char *nptr;
char **endptr;
int base;
{
        static char lower[] = "abcdefghijklmnopqrstuvwxyz";

        unsigned long result = 0UL;
        char *nptr_orig = (char *) nptr;
        int neg = FALSE;
        char *cp, c;
        int val;
        int sawdigs = FALSE;

        /*
         * The strtoul() function converts the initial part of the
         * string in nptr to an unsigned long integer value according
         * to the given base, which must be between 2 and 36 inclusive,
         * or be the special value 0.
         */

        if ((base != 0 && (base < 2 || base > 36)) || nptr == NULL) {
                if (endptr != NULL)
                        *endptr = nptr_orig;
                errno = EINVAL;
                return 0;
        }

        /*
         * The string must [sic] begin with an arbitrary amount of white space
         * (as determined by isspace(3)) followed by a single optional
         * `+' or `-' sign.
         */
        while (isspace(*nptr))
                nptr++;

        if (*nptr == '+')
                nptr++;
        else if (*nptr == '-') {
                nptr++;
                neg = TRUE;
        }

       /*
        * If base is zero or 16, the string may then include a `0x' prefix,
        * and the number will be read in base 16; otherwise, a zero base is
        * taken as 10 (decimal) unless the next character is `0', in which
        * case it is taken as 8 (octal).
        */
       if ((base == 0 || base == 16)
           && nptr[0] == '0'
           && (nptr[1] == 'x' || nptr[1] == 'X')) {
                base = 16;      /* force it */
                nptr += 2;      /* skip 0x */
        } else if ((base == 0 || base == 8) && nptr[0] == '0') {
                base = 8;
                nptr++;
        } else if (base == 0)
                base = 10;

        /*
         * The remainder of the string is converted to an unsigned long int
         * value in the obvious manner, stopping at the first character
         * which is not a valid digit in the given base. (In bases above 10,
         * the letter `A' in either upper or lower case represents 10,
         * `B' represents 11, and so forth, with `Z' representing 35.)
         */
        for (; *nptr != '\0'; nptr++) {
                c = *nptr;
#if defined(HAVE_LOCALE_H)
                if (base == 10
                    && loc.thousands_sep != NULL
                    && loc.thousands_sep[0] != '\0'
                    && c == loc.thousands_sep[0])
                        continue;
#endif
                switch (c) {
                case '0': case '1': case '2':
                case '3': case '4': case '5':
                case '6': case '7': case '8':
                case '9':
                        val = c  - '0';
                        if (val >= base)  /* even base 2 allowed ... */
                                goto out;
                        result *= base;
                        result += val;
                        sawdigs = TRUE;
                        break;
                case 'A': case 'B': case 'C': case 'D': case 'E':
                case 'F': case 'G': case 'H': case 'I': case 'J':
                case 'K': case 'L': case 'M': case 'N': case 'O':
                case 'P': case 'Q': case 'R': case 'S': case 'T':
                case 'U': case 'V': case 'W': case 'X': case 'Y':
                case 'Z':
                        c += 'a' - 'A'; /* downcase */
                        /* fall through */
                case 'a': case 'b': case 'c': case 'd': case 'e':
                case 'f': case 'g': case 'h': case 'i': case 'j':
                case 'k': case 'l': case 'm': case 'n': case 'o':
                case 'p': case 'q': case 'r': case 's': case 't':
                case 'u': case 'v': case 'w': case 'x': case 'y':
                case 'z':
                        cp = strchr(lower, c);
                        val = cp - lower;
                        val += 10;      /* 'a' == 10 */
                        if (val >= base)
                                goto out;
                        result *= base;
                        result += val;
                        sawdigs = TRUE;
                        break;
                default:
                        goto out;
                }
        }
out:
        /*
         * If endptr is not NULL, strtoul() stores the address of the
         * first invalid character in *endptr. If there were no digits
         * at all, strtoul() stores the original value of nptr in *endptr
         * (and returns 0).  In particular, if *nptr is not `\0' but
         * **endptr is `\0' on return, the entire string is valid.
         */
        if (endptr != NULL) {
                if (! sawdigs) {
                        *endptr = nptr_orig;
                        return 0;
                } else
                        *endptr = (char *) nptr;
        }

        /*
         * RETURN VALUE
         * The strtoul() function returns either the result of the
         * conversion or, if there was a leading minus sign, the
         * negation of the result of the conversion, unless the original
         * (non-negated) value would overflow; in the latter case,
         * strtoul() returns ULONG_MAX and sets the global variable errno
         * to ERANGE.
         */

        /*
         * ADR: This computation is probably bogus.  If it's a
         * problem, upgrade to a modern system.
         */
        if (neg && result == ULONG_MAX) {
                errno = ERANGE;
                return ULONG_MAX;
        } else if (neg)
                result = -result;

        return result;
}

#ifdef TEST
#undef strtoul
int main(void)
{
        char *endptr;
        unsigned long res1, res2;

        res1 = strtoul("0xdeadBeeF", & endptr, 0),
        res2 = mystrtoul("0xdeadBeeF", & endptr, 0),
printf("(real,my)strtoul(\"0xdeadBeeF\", & endptr, 0) is %lu, %lu *endptr = %d\n",
                res1, res2, *endptr);

        res1 = strtoul("0101101", & endptr, 2),
        res2 = mystrtoul("0101101", & endptr, 2),
printf("(real,my)strtoul(\"0101101\", & endptr, 2) is %lu, %lu *endptr = %d\n",
                res1, res2, *endptr);

        res1 = strtoul("01011012", & endptr, 2),
        res2 = mystrtoul("01011012", & endptr, 2),
printf("(real,my)strtoul(\"01011012\", & endptr, 2) is %lu, %lu *endptr = %d\n",
                res1, res2, *endptr);

        res1 = strtoul("  +42a", & endptr, 0),
        res2 = mystrtoul("  +42a", & endptr, 0),
printf("(real,my)strtoul(\"  +42a\", & endptr, 0) is %lu, %lu *endptr = %d\n",
                res1, res2, *endptr);

        res1 = strtoul("0377", & endptr, 0),
        res2 = mystrtoul("0377", & endptr, 0),
printf("(real,my)strtoul(\"0377\", & endptr, 0) is %lu, %lu *endptr = %d\n",
                res1, res2, *endptr);

        res1 = strtoul("Z", & endptr, 36),
        res2 = mystrtoul("Z", & endptr, 36),
printf("(real,my)strtoul(\"Z\", & endptr, 36) is %lu, %lu *endptr = %d\n",
                res1, res2, *endptr);

        res1 = strtoul("qZ*", & endptr, 36),
        res2 = mystrtoul("qZ*", & endptr, 36),
printf("(real,my)strtoul(\"qZ*\", & endptr, 36) is %lu, %lu *endptr = %d\n",
                res1, res2, *endptr);
}
#endif