nasmlib/numstr.c

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#include "nasmlib.h"

/*
 * Produce an unsigned integer string from a number with a specified
 * base, digits and signedness.
 */
int numstr(char *buf, size_t buflen, uint64_t n,
           int digits, unsigned int base, bool ucase)
{
    static const char digit_chars[2][NUMSTR_MAXBASE+1] =
    {
        /* Lower case version */
        "0123456789"
        "abcdefghijklmnopqrstuvwxyz"
        "ABCDEFGHIJKLMNOPQRSTUVWXYZ"
        "@_",

        /* Upper case version */
        "0123456789"
        "ABCDEFGHIJKLMNOPQRSTUVWXYZ"
        "abcdefghijklmnopqrstuvwxyz"
        "@_"
    };
    const char * const dchars = digit_chars[ucase];
    bool moredigits = digits <= 0;
    char *p;
    int len;

    if (base < 2 || base > NUMSTR_MAXBASE)
        return -1;

    if (moredigits)
        digits = -digits;

    p = buf + buflen;
    *--p = '\0';

    while (p > buf && (digits-- > 0 || (moredigits && n))) {
        *--p = dchars[n % base];
        n /= base;
    }

    len = buflen - (p - buf);   /* Including final null */
    if (p != buf)
        memmove(buf, p, len);

    return len - 1;
}