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char * ltoa (long val, char *buf, unsigned radix)
{
    char *p;            /* pointer to traverse string */
    char *firstdig;        /* pointer to first digit */
    char temp;            /* temp char */
    unsigned digval;    /* value of digit */

    p = buf;

    if (radix == 10 && val < 0) { /* negative, so output '-' and negate */
        *p++ = '-';
        val = (unsigned long)(-(long)val);
    }

    firstdig = p;    /* save pointer to first digit */

    do {
        digval = (unsigned) (val % radix);
        val /= radix; /* get next digit */

        /* convert to ascii and store */
        if (digval > 9)
            *p++ = (char) (digval - 10 + 'a');    /* a letter */
        else
            *p++ = (char) (digval + '0');        /* a digit */
    } while (val > 0);

    /* We now have the digit of the number in the buffer, but in reverse order. Thus we reverse them now. */

    *p-- = '\0';    /* terminate string; p points to last digit */

    do {
        temp = *p;
        *p = *firstdig;
        *firstdig = temp; /* swap *p and *firstdig */
        --p;
        ++firstdig; /* advance to next two digits */
        } while (firstdig < p); /* repeat until halfway */

    return buf;
}