[PATCH] zlib_inflate: Upgrade library code to a recent version

Upgrade the zlib_inflate implementation in the kernel from a patched
version 1.1.3/4 to a patched 1.2.3.

The code in the kernel is about seven years old and I noticed that the
external zlib library's inflate performance was significantly faster (~50%)
than the code in the kernel on ARM (and faster again on x86_32).

For comparison the newer deflate code is 20% slower on ARM and 50% slower
on x86_32 but gives an approx 1% compression ratio improvement.  I don't
consider this to be an improvement for kernel use so have no plans to
change the zlib_deflate code.

Various changes have been made to the zlib code in the kernel, the most
significant being the extra functions/flush option used by ppp_deflate.
This update reimplements the features PPP needs to ensure it continues to
work.

This code has been tested on ARM under both JFFS2 (with zlib compression
enabled) and ppp_deflate and on x86_32.  JFFS2 sees an approx.  10% real
world file read speed improvement.

This patch also removes ZLIB_VERSION as it no longer has a correct value.
We don't need version checks anyway as the kernel's module handling will
take care of that for us.  This removal is also more in keeping with the
zlib author's wishes (http://www.zlib.net/zlib_faq.html#faq24) and I've
added something to the zlib.h header to note its a modified version.

Signed-off-by: Richard Purdie <rpurdie@rpsys.net>
Acked-by: Joern Engel <joern@wh.fh-wedel.de>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

1 files changed, 45 insertions, 54 deletions

diff --git a/lib/zlib_inflate/inftrees.h b/lib/zlib_inflate/inftrees.h
index e37705adc00..5f5219b1240 100644
--- a/lib/zlib_inflate/inftrees.h
+++ b/lib/zlib_inflate/inftrees.h
@@ -1,6 +1,6 @@
 /* inftrees.h -- header to use inftrees.c
- * Copyright (C) 1995-1998 Mark Adler
- * For conditions of distribution and use, see copyright notice in zlib.h 
+ * Copyright (C) 1995-2005 Mark Adler
+ * For conditions of distribution and use, see copyright notice in zlib.h
  */
 
 /* WARNING: this file should *not* be used by applications. It is
@@ -8,57 +8,48 @@
    subject to change. Applications should only use zlib.h.
  */
 
-/* Huffman code lookup table entry--this entry is four bytes for machines
-   that have 16-bit pointers (e.g. PC's in the small or medium model). */
-
-#ifndef _INFTREES_H
-#define _INFTREES_H
-
-typedef struct inflate_huft_s inflate_huft;
-
-struct inflate_huft_s {
-  union {
-    struct {
-      Byte Exop;        /* number of extra bits or operation */
-      Byte Bits;        /* number of bits in this code or subcode */
-    } what;
-    uInt pad;           /* pad structure to a power of 2 (4 bytes for */
-  } word;               /*  16-bit, 8 bytes for 32-bit int's) */
-  uInt base;            /* literal, length base, distance base,
-                           or table offset */
-};
+/* Structure for decoding tables.  Each entry provides either the
+   information needed to do the operation requested by the code that
+   indexed that table entry, or it provides a pointer to another
+   table that indexes more bits of the code.  op indicates whether
+   the entry is a pointer to another table, a literal, a length or
+   distance, an end-of-block, or an invalid code.  For a table
+   pointer, the low four bits of op is the number of index bits of
+   that table.  For a length or distance, the low four bits of op
+   is the number of extra bits to get after the code.  bits is
+   the number of bits in this code or part of the code to drop off
+   of the bit buffer.  val is the actual byte to output in the case
+   of a literal, the base length or distance, or the offset from
+   the current table to the next table.  Each entry is four bytes. */
+typedef struct {
+    unsigned char op;           /* operation, extra bits, table bits */
+    unsigned char bits;         /* bits in this part of the code */
+    unsigned short val;         /* offset in table or code value */
+} code;
+
+/* op values as set by inflate_table():
+    00000000 - literal
+    0000tttt - table link, tttt != 0 is the number of table index bits
+    0001eeee - length or distance, eeee is the number of extra bits
+    01100000 - end of block
+    01000000 - invalid code
+ */
 
 /* Maximum size of dynamic tree.  The maximum found in a long but non-
-   exhaustive search was 1004 huft structures (850 for length/literals
-   and 154 for distances, the latter actually the result of an
-   exhaustive search).  The actual maximum is not known, but the
-   value below is more than safe. */
-#define MANY 1440
-
-extern int zlib_inflate_trees_bits (
-    uInt *,                     /* 19 code lengths */
-    uInt *,                     /* bits tree desired/actual depth */
-    inflate_huft **,            /* bits tree result */
-    inflate_huft *,             /* space for trees */
-    z_streamp);                 /* for messages */
-
-extern int zlib_inflate_trees_dynamic (
-    uInt,                       /* number of literal/length codes */
-    uInt,                       /* number of distance codes */
-    uInt *,                     /* that many (total) code lengths */
-    uInt *,                     /* literal desired/actual bit depth */
-    uInt *,                     /* distance desired/actual bit depth */
-    inflate_huft **,            /* literal/length tree result */
-    inflate_huft **,            /* distance tree result */
-    inflate_huft *,             /* space for trees */
-    z_streamp);                 /* for messages */
-
-extern int zlib_inflate_trees_fixed (
-    uInt *,                     /* literal desired/actual bit depth */
-    uInt *,                     /* distance desired/actual bit depth */
-    inflate_huft **,            /* literal/length tree result */
-    inflate_huft **,            /* distance tree result */
-    inflate_huft *,             /* space for trees */
-    z_streamp);                 /* for memory allocation */
-
-#endif /* _INFTREES_H */
+   exhaustive search was 1444 code structures (852 for length/literals
+   and 592 for distances, the latter actually the result of an
+   exhaustive search).  The true maximum is not known, but the value
+   below is more than safe. */
+#define ENOUGH 2048
+#define MAXD 592
+
+/* Type of code to build for inftable() */
+typedef enum {
+    CODES,
+    LENS,
+    DISTS
+} codetype;
+
+extern int zlib_inflate_table (codetype type, unsigned short *lens,
+                             unsigned codes, code **table,
+                             unsigned *bits, unsigned short *work);