From: Chris Moore <moore@free.fr>
To: u-boot@lists.denx.de
Subject: [U-Boot] [PATCH V3 1/3] lib_generic memcpy: copy one word at a time if possible
Date: Mon, 12 Oct 2009 06:37:12 +0200 [thread overview]
Message-ID: <4AD2B278.4010103@free.fr> (raw)
In-Reply-To: <20091010074431.GA3732@mail.gnudd.com>
Hi Alessandro,
Alessandro Rubini a ?crit :
>>> + unsigned long *dl = (unsigned long *)dest, *sl = (unsigned long *)src;
>>>
>
>
>> Nitpick: Are you sure the casts are necessary here ?
>>
>
> Without the one on src it complains because of "const". So I write
> both for symetry.
>
Yes, of course, you and the compiler are absolutely right.
Silly me, I completely overlooked the const :(
To me casting away const is a cardinal sin (it rather defeats the
object) and I find that the ease with which it can be done in C is
frightening.
So I feel obliged to (hopefully) correct my submission:
void *memcpy(void *dest, const void *src, size_t count)
{
char *d8;
const char *s8;
unsigned long *dl = dest;
const unsigned long *sl = src;
/* while all data is aligned (common case), copy multiple bytes at a time */
if ( (((int)(long)dest | (int)(long)src) & (sizeof(*dl) - 1)) == 0) {
while (count >= sizeof(*dl)) {
*dl++ = *sl++;
count -= sizeof(*dl);
}
}
d8 = (char *)dl;
s8 = (const char *)sl;
/* copy any remaining data byte by byte */
while (count--)
*d8++ = *s8++;
return dest;
}
But this is still not even compile tested :(
I never learn :(
Cheers,
Chris
prev parent reply other threads:[~2009-10-12 4:37 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2009-10-09 9:12 [U-Boot] [PATCH V3 1/3] lib_generic memcpy: copy one word at a time if possible Alessandro Rubini
2009-10-09 10:21 ` Mike Frysinger
2009-10-09 10:50 ` Alessandro Rubini
2009-10-10 6:13 ` Chris Moore
2009-10-10 7:44 ` Alessandro Rubini
2009-10-12 4:37 ` Chris Moore [this message]
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