[PATCH] zlib: Optimize inffast when copying direct from output

[Joakim Tjernlund]

JFFS2 uses lesser compression ratio and inflate always
ends up in "copy direct from output" case.
This patch tries to optimize the copy procedure for
arch's that have CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS defined.
On my MPC8321 this is about 14% faster on my JFFS2 root FS
than the original.

Signed-off-by: Joakim Tjernlund <Joakim.Tjernlund@xxxxxxxxxxxx>
---
 lib/zlib_inflate/inffast.c |   35 +++++++++++++++++++++++++++++++++++
 1 files changed, 35 insertions(+), 0 deletions(-)

diff --git a/lib/zlib_inflate/inffast.c b/lib/zlib_inflate/inffast.c
index 8550b0c..0588fbf 100644
--- a/lib/zlib_inflate/inffast.c
+++ b/lib/zlib_inflate/inffast.c
@@ -240,6 +240,40 @@ 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;
+
+			do
+			    PUP(sout) = PUP(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);
+			unsigned short pat16;
+			unsigned long loops = len >> 1;
+
+			pat16 = *(sout-2+2*OFF);
+			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);
@@ -251,6 +285,7 @@ void inflate_fast(z_streamp strm, unsigned start)
                         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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