ndjbdns/byte_diff.c at master · matthias2/ndjbdns · GitHub

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#include "byte.h"

int
byte_diff (register char *s, register unsigned int n, register char *t)
{
    for (;;)
    {
        if (!n)
            return 0;
        if (*s != *t)
            break;
        ++s;
        ++t;
        --n;

        if (!n)
            return 0;
        if (*s != *t)
            break;
        ++s;
        ++t;
        --n;

        if (!n)
            return 0;
        if (*s != *t)
            break;
        ++s;
        ++t;
        --n;

        if (!n)
            return 0;
        if (*s != *t)
            break;
        ++s;
        ++t;
        --n;
    }

    return ((int)(unsigned int)(unsigned char) *s)
                           - ((int)(unsigned int)(unsigned char) *t);
}