Re: Memory corruption in 8390.c ?

[Ben Pfaff <blp@cs.stanford.edu>]

Alan Cox <alan@lxorguk.ukuu.org.uk> writes:

> Ar Mer, 2006-06-21 am 10:23 -0700, ysgrifennodd Ben Pfaff:
>> > +		memset(buf, 0, ETH_ZLEN);	/* more efficient than doing just the needed bits */
>> > +		memcpy(buf, data, ETH_ZLEN);
>> 
>> Is this really correct?  It zeros out ETH_ZLEN bytes only to
>> immediately copy over all of them again.
>
> When I did it originally I tested with rdtsc and its actually quicker to
> let it build the static memset the copy data over it than to do the
> extra maths and the variable length loop.
>
> Hence the comment

You are saying that this:
        memset(buf, 0, ETH_ZLEN);
        memcpy(buf, data, ETH_ZLEN);
is faster than this?
        memcpy(buf, data, ETH_ZLEN);

Because as far as I can tell they are equivalent.
-- 
Ben Pfaff 
email: blp@cs.stanford.edu
web: http://benpfaff.org