Date: Thu, 2 Sep 2004 10:36:26 -0700
From: Tom Rini <trini@kernel.crashing.org>
To: Kernel Mailing List <linux-kernel@vger.kernel.org>
Cc: Paul Mackerras <paulus@samba.org>
Subject: [PATCH,RFC 2.6.9-rc1 1/2] zlib_inflate: Move zlib_inflateSync & friends
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References: <20040901231659.GA20624@smtp.west.cox.net>
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On Wed, Sep 01, 2004 at 04:17:00PM -0700, Tom Rini wrote:

> The following patch switches arch/ppc/boot over from using its own
> version of zlib to the code found under lib/zlib_inflate.  The plus side
> to this, is one less version of zlib stuff around in the kernel.  The
> downside is that the zlib code is ~8kB larger now, so I'm not sure if
> this is a good idea.

So, to try and get around this growth in size, I decided to see how bad
things would look, and how much it would take, to get the size back down
to what it was.  After messing around, I've come up with two patches,
which in the end shrink the overall size slightly.  The first, and I
hope least objectionable is to move zlib_inflateSync, and related bits
used by PPP into inflate_sync.c.  This saves us 169 bytes.

Signed-off-by: Tom Rini <trini@kernel.crashing.org>

Index: linux-2.6/lib/zlib_inflate/inflate_sync.c
===================================================================
--- /dev/null
+++ linux-2.6/lib/zlib_inflate/inflate_sync.c
@@ -0,0 +1,148 @@
+/* inflate.c -- zlib interface to inflate modules
+ * Copyright (C) 1995-1998 Mark Adler
+ * For conditions of distribution and use, see copyright notice in zlib.h 
+ */
+
+#include <linux/zutil.h>
+#include "infblock.h"
+#include "infutil.h"
+
+int zlib_inflateSync(
+	z_streamp z
+)
+{
+  uInt n;       /* number of bytes to look at */
+  Byte *p;      /* pointer to bytes */
+  uInt m;       /* number of marker bytes found in a row */
+  uLong r, w;   /* temporaries to save total_in and total_out */
+
+  /* set up */
+  if (z == NULL || z->state == NULL)
+    return Z_STREAM_ERROR;
+  if (z->state->mode != I_BAD)
+  {
+    z->state->mode = I_BAD;
+    z->state->sub.marker = 0;
+  }
+  if ((n = z->avail_in) == 0)
+    return Z_BUF_ERROR;
+  p = z->next_in;
+  m = z->state->sub.marker;
+
+  /* search */
+  while (n && m < 4)
+  {
+    static const Byte mark[4] = {0, 0, 0xff, 0xff};
+    if (*p == mark[m])
+      m++;
+    else if (*p)
+      m = 0;
+    else
+      m = 4 - m;
+    p++, n--;
+  }
+
+  /* restore */
+  z->total_in += p - z->next_in;
+  z->next_in = p;
+  z->avail_in = n;
+  z->state->sub.marker = m;
+
+  /* return no joy or set up to restart on a new block */
+  if (m != 4)
+    return Z_DATA_ERROR;
+  r = z->total_in;  w = z->total_out;
+  zlib_inflateReset(z);
+  z->total_in = r;  z->total_out = w;
+  z->state->mode = BLOCKS;
+  return Z_OK;
+}
+
+
+/* Returns true if inflate is currently at the end of a block generated
+ * by Z_SYNC_FLUSH or Z_FULL_FLUSH. This function is used by one PPP
+ * implementation to provide an additional safety check. PPP uses Z_SYNC_FLUSH
+ * but removes the length bytes of the resulting empty stored block. When
+ * decompressing, PPP checks that at the end of input packet, inflate is
+ * waiting for these length bytes.
+ */
+int zlib_inflateSyncPoint(
+	z_streamp z
+)
+{
+  if (z == NULL || z->state == NULL || z->state->blocks == NULL)
+    return Z_STREAM_ERROR;
+  return zlib_inflate_blocks_sync_point(z->state->blocks);
+}
+
+/*
+ * This subroutine adds the data at next_in/avail_in to the output history
+ * without performing any output.  The output buffer must be "caught up";
+ * i.e. no pending output (hence s->read equals s->write), and the state must
+ * be BLOCKS (i.e. we should be willing to see the start of a series of
+ * BLOCKS).  On exit, the output will also be caught up, and the checksum
+ * will have been updated if need be.
+ */
+static int zlib_inflate_addhistory(inflate_blocks_statef *s,
+				      z_stream              *z)
+{
+    uLong b;              /* bit buffer */  /* NOT USED HERE */
+    uInt k;               /* bits in bit buffer */ /* NOT USED HERE */
+    uInt t;               /* temporary storage */
+    Byte *p;              /* input data pointer */
+    uInt n;               /* bytes available there */
+    Byte *q;              /* output window write pointer */
+    uInt m;               /* bytes to end of window or read pointer */
+
+    if (s->read != s->write)
+	return Z_STREAM_ERROR;
+    if (s->mode != TYPE)
+	return Z_DATA_ERROR;
+
+    /* we're ready to rock */
+    LOAD
+    /* while there is input ready, copy to output buffer, moving
+     * pointers as needed.
+     */
+    while (n) {
+	t = n;  /* how many to do */
+	/* is there room until end of buffer? */
+	if (t > m) t = m;
+	/* update check information */
+	if (s->checkfn != NULL)
+	    s->check = (*s->checkfn)(s->check, q, t);
+	memcpy(q, p, t);
+	q += t;
+	p += t;
+	n -= t;
+	z->total_out += t;
+	s->read = q;    /* drag read pointer forward */
+/*      WWRAP  */ 	/* expand WWRAP macro by hand to handle s->read */
+	if (q == s->end) {
+	    s->read = q = s->window;
+	    m = WAVAIL;
+	}
+    }
+    UPDATE
+    return Z_OK;
+}
+
+
+/*
+ * This subroutine adds the data at next_in/avail_in to the output history
+ * without performing any output.  The output buffer must be "caught up";
+ * i.e. no pending output (hence s->read equals s->write), and the state must
+ * be BLOCKS (i.e. we should be willing to see the start of a series of
+ * BLOCKS).  On exit, the output will also be caught up, and the checksum
+ * will have been updated if need be.
+ */
+
+int zlib_inflateIncomp(
+	z_stream *z
+	
+)
+{
+    if (z->state->mode != BLOCKS)
+	return Z_DATA_ERROR;
+    return zlib_inflate_addhistory(z->state->blocks, z);
+}
Index: linux-2.6/lib/zlib_inflate/Makefile
===================================================================
--- linux-2.6.orig/lib/zlib_inflate/Makefile
+++ linux-2.6/lib/zlib_inflate/Makefile
@@ -16,4 +16,4 @@
 obj-$(CONFIG_ZLIB_INFLATE) += zlib_inflate.o
 
 zlib_inflate-objs := infblock.o infcodes.o inffast.o inflate.o \
-		     inftrees.o infutil.o inflate_syms.o
+		     inflate_sync.o inftrees.o infutil.o inflate_syms.o
Index: linux-2.6/lib/zlib_inflate/inflate.c
===================================================================
--- linux-2.6.orig/lib/zlib_inflate/inflate.c
+++ linux-2.6/lib/zlib_inflate/inflate.c
@@ -248,144 +248,3 @@ int zlib_inflate(
   z->state->sub.marker = 0;       /* can try inflateSync */
   return Z_DATA_ERROR;
 }
-
-
-int zlib_inflateSync(
-	z_streamp z
-)
-{
-  uInt n;       /* number of bytes to look at */
-  Byte *p;      /* pointer to bytes */
-  uInt m;       /* number of marker bytes found in a row */
-  uLong r, w;   /* temporaries to save total_in and total_out */
-
-  /* set up */
-  if (z == NULL || z->state == NULL)
-    return Z_STREAM_ERROR;
-  if (z->state->mode != I_BAD)
-  {
-    z->state->mode = I_BAD;
-    z->state->sub.marker = 0;
-  }
-  if ((n = z->avail_in) == 0)
-    return Z_BUF_ERROR;
-  p = z->next_in;
-  m = z->state->sub.marker;
-
-  /* search */
-  while (n && m < 4)
-  {
-    static const Byte mark[4] = {0, 0, 0xff, 0xff};
-    if (*p == mark[m])
-      m++;
-    else if (*p)
-      m = 0;
-    else
-      m = 4 - m;
-    p++, n--;
-  }
-
-  /* restore */
-  z->total_in += p - z->next_in;
-  z->next_in = p;
-  z->avail_in = n;
-  z->state->sub.marker = m;
-
-  /* return no joy or set up to restart on a new block */
-  if (m != 4)
-    return Z_DATA_ERROR;
-  r = z->total_in;  w = z->total_out;
-  zlib_inflateReset(z);
-  z->total_in = r;  z->total_out = w;
-  z->state->mode = BLOCKS;
-  return Z_OK;
-}
-
-
-/* Returns true if inflate is currently at the end of a block generated
- * by Z_SYNC_FLUSH or Z_FULL_FLUSH. This function is used by one PPP
- * implementation to provide an additional safety check. PPP uses Z_SYNC_FLUSH
- * but removes the length bytes of the resulting empty stored block. When
- * decompressing, PPP checks that at the end of input packet, inflate is
- * waiting for these length bytes.
- */
-int zlib_inflateSyncPoint(
-	z_streamp z
-)
-{
-  if (z == NULL || z->state == NULL || z->state->blocks == NULL)
-    return Z_STREAM_ERROR;
-  return zlib_inflate_blocks_sync_point(z->state->blocks);
-}
-
-/*
- * This subroutine adds the data at next_in/avail_in to the output history
- * without performing any output.  The output buffer must be "caught up";
- * i.e. no pending output (hence s->read equals s->write), and the state must
- * be BLOCKS (i.e. we should be willing to see the start of a series of
- * BLOCKS).  On exit, the output will also be caught up, and the checksum
- * will have been updated if need be.
- */
-static int zlib_inflate_addhistory(inflate_blocks_statef *s,
-				      z_stream              *z)
-{
-    uLong b;              /* bit buffer */  /* NOT USED HERE */
-    uInt k;               /* bits in bit buffer */ /* NOT USED HERE */
-    uInt t;               /* temporary storage */
-    Byte *p;              /* input data pointer */
-    uInt n;               /* bytes available there */
-    Byte *q;              /* output window write pointer */
-    uInt m;               /* bytes to end of window or read pointer */
-
-    if (s->read != s->write)
-	return Z_STREAM_ERROR;
-    if (s->mode != TYPE)
-	return Z_DATA_ERROR;
-
-    /* we're ready to rock */
-    LOAD
-    /* while there is input ready, copy to output buffer, moving
-     * pointers as needed.
-     */
-    while (n) {
-	t = n;  /* how many to do */
-	/* is there room until end of buffer? */
-	if (t > m) t = m;
-	/* update check information */
-	if (s->checkfn != NULL)
-	    s->check = (*s->checkfn)(s->check, q, t);
-	memcpy(q, p, t);
-	q += t;
-	p += t;
-	n -= t;
-	z->total_out += t;
-	s->read = q;    /* drag read pointer forward */
-/*      WWRAP  */ 	/* expand WWRAP macro by hand to handle s->read */
-	if (q == s->end) {
-	    s->read = q = s->window;
-	    m = WAVAIL;
-	}
-    }
-    UPDATE
-    return Z_OK;
-}
-
-
-/*
- * This subroutine adds the data at next_in/avail_in to the output history
- * without performing any output.  The output buffer must be "caught up";
- * i.e. no pending output (hence s->read equals s->write), and the state must
- * be BLOCKS (i.e. we should be willing to see the start of a series of
- * BLOCKS).  On exit, the output will also be caught up, and the checksum
- * will have been updated if need be.
- */
-
-int zlib_inflateIncomp(
-	z_stream *z
-	
-)
-{
-    if (z->state->mode != BLOCKS)
-	return Z_DATA_ERROR;
-    return zlib_inflate_addhistory(z->state->blocks, z);
-}

-- 
Tom Rini
http://gate.crashing.org/~trini/
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