server/src/util/base36.c

/*
Copyright (c) 1998-2019, Enno Rehling <enno@eressea.de>
Katja Zedel <katze@felidae.kn-bremen.de
Christian Schlittchen <corwin@amber.kn-bremen.de>

Permission to use, copy, modify, and/or distribute this software for any
purpose with or without fee is hereby granted, provided that the above
copyright notice and this permission notice appear in all copies.

THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
ANY SPECIAL, DIRECT, 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.
**/

#include <platform.h>
#include "base36.h"
#include "log.h"

#include <stdlib.h>
#include <assert.h>
#include <ctype.h>

int atoi36(const char *str)
{
    /* cannot use strtol, because invalid strings will cause crash */
    const unsigned char *s = (const unsigned char *)str;
    int i = 0, sign = 1;
    assert(s);
    if (!(*s))
        return 0;
    if (*s == '-') {
        sign = -1;
        ++s;
    }
    while (isalnum(*(unsigned char *)s)) {
        if (islower(*s))
            i = i * 36 + (*s) - 'a' + 10;
        else if (isdigit(*s))
            i = i * 36 + (*s) - '0';
        else if (isupper(*(unsigned char *)s))
            i = i * 36 + (*s) - 'A' + 10;
        else
            break;
        ++s;
    }
    if (i < 0)
        return 0;
    return i * sign;
}

const char *itoab_r(int i, int base, char *s, size_t len)
{
    char *dst;

    assert(len > 2);
    dst = s + len - 2;
    dst[1] = 0;
    if (i != 0) {
        int neg = 0;

        if (i < 0) {
            i = -i;
            neg = 1;
        }
        while (i && dst >= s) {
            int x = i % base;
            i = i / base;
            if (x < 10) {
                *(dst--) = (char)('0' + x);
            }
            else if ('a' + x - 10 == 'l') {
                *(dst--) = 'L';
            }
            else {
                *(dst--) = (char)('a' + (x - 10));
            }
        }
        if (dst > s) {
            if (neg) {
                *(dst) = '-';
            }
            else {
                ++dst;
            }
        }
        else {
            log_error("static buffer exhausted, itoab(%d, %d)", i, base);
            assert(i == 0 || !"itoab: static buffer exhausted");
        }
    }
    else {
        dst[0] = '0';
    }

    return dst;
}

const char *itoa36_r(int i, char *result, size_t len)
{
    return itoab_r(i, 36, result, len);
}
 
const char *itoab(int i, int base)
{
    static char sstr[80];
    char *s;
    static int index = 0;         /* STATIC_XCALL: used across calls */

    s = sstr + (index * 20);
    index = (index + 1) & 3;      /* quick for % 4 */

    return itoab_r(i, base, s, 20);
}

const char *itoa36(int i)
{
    return itoab(i, 36);
}

const char *itoa10(int i)
{
    return itoab(i, 10);
}