windows-server-2003/inetcore/setup/sdslib/ultoa.c

#include <windows.h>

/* helper routine that does the main job. */

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

        p = buf;

        if (is_neg) {
            /* 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 */
}

/* Actual functions just call conversion helper with neg flag set correctly,
   and return pointer to buffer. */

PSTR ULtoA( unsigned long val, char *buf, int radix )
{
        xtoa(val, buf, radix, 0);
        return buf;
}