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Date: Thu, 12 Nov 2009 00:46:41 +0100
From: roel kluin <roel.kluin@...il.com>
To: Joakim Tjernlund <Joakim.Tjernlund@...nsmode.se>
Cc: akpm@...ux-foundation.org, Richard Purdie <rpurdie@...ys.net>,
linux-kernel@...r.kernel.org
Subject: Re: [PATCH] zlib: Optimize inffast even more
On Mon, Nov 9, 2009 at 11:22 AM, Joakim Tjernlund
<Joakim.Tjernlund@...nsmode.se> wrote:
> This improves zlib: Optimize inffast when copying direct from output
> and gives another 3-4% improvement for my MPC8321 target.
> Does not need CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS,
> uses get_unaligned() but only in one place.
> The copy loop just above this one can also use this
> optimization, but I havn't done so as I have not tested if it
> is a win there too.
>
> Signed-off-by: Joakim Tjernlund <Joakim.Tjernlund@...nsmode.se>
> ---
> @@ -240,52 +243,49 @@ void inflate_fast(z_streamp strm, unsigned start)
> }
> else {
> from = out - dist; /* copy direct from output */
> -#ifdef CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS
> /* minimum length is three */
> if (dist > 2 ) {
> - unsigned short *sout = (unsigned short *)(out - OFF);
> - unsigned short *sfrom = (unsigned short *)(from - OFF);
> - unsigned long loops = len >> 1;
> + unsigned short *sout;
> + unsigned short *sfrom;
> + unsigned long loops;
>
> + /* Align out addr, only sfrom might be unaligned */
> + if (!((long)(out - 1 + OFF)) & 1) {
I think this is wrong
did you mean
if (!((long)(out - 1 + OFF) & 1))
> + PUP(out) = PUP(from);
> + len--;
> + }
> + sout = (unsigned short *)(out - OFF);
> + sfrom = (unsigned short *)(from - OFF);
> + loops = len >> 1;
> do
> - PUP(sout) = PUP(sfrom);
> + PUP(sout) = UP_UNALIGNED(sfrom);
> while (--loops);
> out = (unsigned char *)sout + OFF;
> from = (unsigned char *)sfrom + OFF;
> if (len & 1)
> PUP(out) = PUP(from);
> - } else if (dist == 2) {
> - unsigned short *sout = (unsigned short *)(out - OFF);
> + } else { /* dist == 1 or dist == 2 */
> + unsigned short *sout;
> unsigned short pat16;
> - unsigned long loops = len >> 1;
> + unsigned long loops;
>
> + /* Align out addr */
> + if (!((long)(out - 1 + OFF)) & 1) {
and
if (!((long)(out - 1 + OFF) & 1))
> + PUP(out) = PUP(from);
> + len--;
> + }
> + sout = (unsigned short *)(out - OFF);
> pat16 = *(sout-2+2*OFF);
> + if (dist == 1)
> + pat16 = (pat16 & 0xff) | ((pat16 & 0xff ) << 8);
> + loops = len >> 1;
> do
> PUP(sout) = pat16;
> while (--loops);
> out = (unsigned char *)sout + OFF;
> if (len & 1)
> PUP(out) = PUP(from);
> - } else {
> - unsigned char pat8 = *(out - 1 + OFF);
> -
> - do {
> - PUP(out) = pat8;
> - } while (--len);
> }
> -#else
> - do { /* minimum length is three */
> - PUP(out) = PUP(from);
> - PUP(out) = PUP(from);
> - PUP(out) = PUP(from);
> - len -= 3;
> - } while (len > 2);
> - if (len) {
> - PUP(out) = PUP(from);
> - if (len > 1)
> - PUP(out) = PUP(from);
> - }
> -#endif
> }
> }
> else if ((op & 64) == 0) { /* 2nd level distance code */
> --
> 1.6.4.4
>
> --
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