Subject: Suspend 2 merge: 46/51: LZF support.
From: Nigel Cunningham <ncunningham@linuxmail.org>
Reply-To: ncunningham@linuxmail.org
To: Linux Kernel Mailing List <linux-kernel@vger.kernel.org>
In-Reply-To: <1101292194.5805.180.camel@desktop.cunninghams>
References: <1101292194.5805.180.camel@desktop.cunninghams>
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Date: Thu, 25 Nov 2004 00:02:09 +1100
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This is LZF support, contributed under a dual license (see below) by
Marc Lehmann. It flies! (Those stats in the debug info in an earlier
patch were real!).

diff -ruN 852-lzf-old/kernel/power/lzf/lzf_c.c 852-lzf-new/kernel/power/lzf/lzf_c.c
--- 852-lzf-old/kernel/power/lzf/lzf_c.c	1970-01-01 10:00:00.000000000 +1000
+++ 852-lzf-new/kernel/power/lzf/lzf_c.c	2004-11-04 16:27:41.000000000 +1100
@@ -0,0 +1,220 @@
+/*
+ * Copyright (c) 2000-2003 Marc Alexander Lehmann <pcg@goof.com>
+ * 
+ * Redistribution and use in source and binary forms, with or without modifica-
+ * tion, are permitted provided that the following conditions are met:
+ * 
+ *   1.  Redistributions of source code must retain the above copyright notice,
+ *       this list of conditions and the following disclaimer.
+ * 
+ *   2.  Redistributions in binary form must reproduce the above copyright
+ *       notice, this list of conditions and the following disclaimer in the
+ *       documentation and/or other materials provided with the distribution.
+ * 
+ *   3.  The name of the author may not be used to endorse or promote products
+ *       derived from this software without specific prior written permission.
+ * 
+ * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR IMPLIED
+ * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MER-
+ * CHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.  IN NO
+ * EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPE-
+ * CIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
+ * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS;
+ * OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
+ * WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTH-
+ * ERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
+ * OF THE POSSIBILITY OF SUCH DAMAGE.
+ *
+ * Alternatively, the contents of this file may be used under the terms of
+ * the GNU General Public License version 2 (the "GPL"), in which case the
+ * provisions of the GPL are applicable instead of the above. If you wish to
+ * allow the use of your version of this file only under the terms of the
+ * GPL and not to allow others to use your version of this file under the
+ * BSD license, indicate your decision by deleting the provisions above and
+ * replace them with the notice and other provisions required by the GPL. If
+ * you do not delete the provisions above, a recipient may use your version
+ * of this file under either the BSD or the GPL.
+ */
+
+#define HSIZE (1 << (HLOG))
+
+/*
+ * don't play with this unless you benchmark!
+ * decompression is not dependent on the hash function
+ * the hashing function might seem strange, just believe me
+ * it works ;)
+ */
+#define FRST(p) (((p[0]) << 8) + p[1])
+#define NEXT(v,p) (((v) << 8) + p[2])
+#define IDX(h) ((((h ^ (h << 5)) >> (3*8 - HLOG)) + h*3) & (HSIZE - 1))
+/*
+ * IDX works because it is very similar to a multiplicative hash, e.g.
+ * (h * 57321 >> (3*8 - HLOG))
+ * the next one is also quite good, albeit slow ;)
+ * (int)(cos(h & 0xffffff) * 1e6)
+ */
+
+#if 0
+/* original lzv-like hash function */
+# define FRST(p) (p[0] << 5) ^ p[1]
+# define NEXT(v,p) ((v) << 5) ^ p[2]
+# define IDX(h) ((h) & (HSIZE - 1))
+#endif
+
+#define        MAX_LIT        (1 <<  5)
+#define        MAX_OFF        (1 << 13)
+#define        MAX_REF        ((1 <<  8) + (1 << 3))
+
+/*
+ * compressed format
+ *
+ * 000LLLLL <L+1>    ; literal
+ * LLLOOOOO oooooooo ; backref L
+ * 111OOOOO LLLLLLLL oooooooo ; backref L+7
+ *
+ */
+
+unsigned int
+lzf_compress (const void *const in_data, unsigned int in_len,
+	      void *out_data, unsigned int out_len, void *hbuf)
+{
+  const u8 **htab = hbuf;
+  const u8 **hslot;
+  const u8 *ip = (const u8 *)in_data;
+        u8 *op = (u8 *)out_data;
+  const u8 *in_end  = ip + in_len;
+        u8 *out_end = op + out_len;
+  const u8 *ref;
+
+  unsigned int hval = FRST (ip);
+  unsigned long off;
+           int lit = 0;
+
+#if INIT_HTAB
+# if USE_MEMCPY
+    memset (htab, 0, sizeof (htab));
+# else
+    for (hslot = htab; hslot < htab + HSIZE; hslot++)
+      *hslot++ = ip;
+# endif
+#endif
+
+  for (;;)
+    {
+      if (ip < in_end - 2)
+        {
+          hval = NEXT (hval, ip);
+          hslot = htab + IDX (hval);
+          ref = *hslot; *hslot = ip;
+
+          if (1
+#if INIT_HTAB && !USE_MEMCPY
+              && ref < ip /* the next test will actually take care of this, but this is faster */
+#endif
+              && (off = ip - ref - 1) < MAX_OFF
+              && ip + 4 < in_end
+              && ref > (u8 *)in_data
+#if STRICT_ALIGN
+              && ref[0] == ip[0]
+              && ref[1] == ip[1]
+              && ref[2] == ip[2]
+#else
+              && *(u16 *)ref == *(u16 *)ip
+              && ref[2] == ip[2]
+#endif
+            )
+            {
+              /* match found at *ref++ */
+              unsigned int len = 2;
+              unsigned int maxlen = in_end - ip - len;
+              maxlen = maxlen > MAX_REF ? MAX_REF : maxlen;
+
+              do
+                len++;
+              while (len < maxlen && ref[len] == ip[len]);
+
+              if (op + lit + 1 + 3 >= out_end)
+                return 0;
+
+              if (lit)
+                {
+                  *op++ = lit - 1;
+                  lit = -lit;
+                  do
+                    *op++ = ip[lit];
+                  while (++lit);
+                }
+
+              len -= 2;
+              ip++;
+
+              if (len < 7)
+                {
+                  *op++ = (off >> 8) + (len << 5);
+                }
+              else
+                {
+                  *op++ = (off >> 8) + (  7 << 5);
+                  *op++ = len - 7;
+                }
+
+              *op++ = off;
+
+#if ULTRA_FAST
+              ip += len;
+              hval = FRST (ip);
+              hval = NEXT (hval, ip);
+              htab[IDX (hval)] = ip;
+              ip++;
+#else
+              do
+                {
+                  hval = NEXT (hval, ip);
+                  htab[IDX (hval)] = ip;
+                  ip++;
+                }
+              while (len--);
+#endif
+              continue;
+            }
+        }
+      else if (ip == in_end)
+        break;
+
+      /* one more literal byte we must copy */
+      lit++;
+      ip++;
+
+      if (lit == MAX_LIT)
+        {
+          if (op + 1 + MAX_LIT >= out_end)
+            return 0;
+
+          *op++ = MAX_LIT - 1;
+#if USE_MEMCPY
+          memcpy (op, ip - MAX_LIT, MAX_LIT);
+          op += MAX_LIT;
+          lit = 0;
+#else
+          lit = -lit;
+          do
+            *op++ = ip[lit];
+          while (++lit);
+#endif
+        }
+    }
+
+  if (lit)
+    {
+      if (op + lit + 1 >= out_end)
+	return 0;
+
+      *op++ = lit - 1;
+      lit = -lit;
+      do
+	*op++ = ip[lit];
+      while (++lit);
+    }
+
+  return op - (u8 *) out_data;
+}
diff -ruN 852-lzf-old/kernel/power/lzf/lzf_d.c 852-lzf-new/kernel/power/lzf/lzf_d.c
--- 852-lzf-old/kernel/power/lzf/lzf_d.c	1970-01-01 10:00:00.000000000 +1000
+++ 852-lzf-new/kernel/power/lzf/lzf_d.c	2004-11-04 16:27:41.000000000 +1100
@@ -0,0 +1,98 @@
+/*
+ * Copyright (c) 2000-2002 Marc Alexander Lehmann <pcg@goof.com>
+ * 
+ * Redistribution and use in source and binary forms, with or without modifica-
+ * tion, are permitted provided that the following conditions are met:
+ * 
+ *   1.  Redistributions of source code must retain the above copyright notice,
+ *       this list of conditions and the following disclaimer.
+ * 
+ *   2.  Redistributions in binary form must reproduce the above copyright
+ *       notice, this list of conditions and the following disclaimer in the
+ *       documentation and/or other materials provided with the distribution.
+ * 
+ *   3.  The name of the author may not be used to endorse or promote products
+ *       derived from this software without specific prior written permission.
+ * 
+ * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR IMPLIED
+ * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MER-
+ * CHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.  IN NO
+ * EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPE-
+ * CIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
+ * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS;
+ * OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
+ * WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTH-
+ * ERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
+ * OF THE POSSIBILITY OF SUCH DAMAGE.
+ *
+ * Alternatively, the contents of this file may be used under the terms of
+ * the GNU General Public License version 2 (the "GPL"), in which case the
+ * provisions of the GPL are applicable instead of the above. If you wish to
+ * allow the use of your version of this file only under the terms of the
+ * GPL and not to allow others to use your version of this file under the
+ * BSD license, indicate your decision by deleting the provisions above and
+ * replace them with the notice and other provisions required by the GPL. If
+ * you do not delete the provisions above, a recipient may use your version
+ * of this file under either the BSD or the GPL.
+ */
+
+unsigned int 
+lzf_decompress (const void *const in_data,  unsigned int in_len,
+                void             *out_data, unsigned int out_len)
+{
+  u8 const *ip = in_data;
+  u8       *op = out_data;
+  u8 const *const in_end  = ip + in_len;
+  u8       *const out_end = op + out_len;
+
+  do
+    {
+      unsigned int ctrl = *ip++;
+
+      if (ctrl < (1 << 5)) /* literal run */
+        {
+          ctrl++;
+
+          if (op + ctrl > out_end)
+            return 0;
+
+#if USE_MEMCPY
+          memcpy (op, ip, ctrl);
+          op += ctrl;
+          ip += ctrl;
+#else
+          do
+            *op++ = *ip++;
+          while (--ctrl);
+#endif
+        }
+      else /* back reference */
+        {
+          unsigned int len = ctrl >> 5;
+
+          u8 *ref = op - ((ctrl & 0x1f) << 8) - 1;
+
+          if (len == 7)
+            len += *ip++;
+          
+          ref -= *ip++;
+
+          if (op + len + 2 > out_end)
+            return 0;
+
+          if (ref < (u8 *)out_data)
+            return 0;
+
+          *op++ = *ref++;
+          *op++ = *ref++;
+
+          do
+            *op++ = *ref++;
+          while (--len);
+        }
+    }
+  while (op < out_end && ip < in_end);
+
+  return op - (u8 *)out_data;
+}
+
diff -ruN 852-lzf-old/kernel/power/suspend_lzf.c 852-lzf-new/kernel/power/suspend_lzf.c
--- 852-lzf-old/kernel/power/suspend_lzf.c	1970-01-01 10:00:00.000000000 +1000
+++ 852-lzf-new/kernel/power/suspend_lzf.c	2004-11-11 08:46:15.000000000 +1100
@@ -0,0 +1,554 @@
+/*
+ * kernel/power/lzf_compress.c
+ *
+ * Copyright (C) 2003 Marc Lehmann <pcg@goof.com>
+ * Copyright (C) 2003,2004 Nigel Cunningham <ncunningham@linuxmail.org>
+ *
+ * This file is released under the GPLv2.
+ *
+ * This file contains data compression routines for suspend,
+ * using LZH compression.
+ *
+ */
+
+#include <linux/suspend.h>
+#include <linux/module.h>
+#include <linux/highmem.h>
+#include <linux/vmalloc.h>
+
+#include "plugins.h"
+#include "proc.h"
+#include "suspend.h"
+
+static int expected_lzf_compression = 0;
+
+/*
+ * size of hashtable is (1 << HLOG) * sizeof (char *)
+ * decompression is independent of the hash table size
+ * the difference between 15 and 14 is very small
+ * for small blocks (and 14 is also faster).
+ * For a low-memory configuration, use HLOG == 13;
+ * For best compression, use 15 or 16.
+ */
+#ifndef HLOG
+# define HLOG 14
+#endif
+
+/*
+ * sacrifice some compression quality in favour of compression speed.
+ * (roughly 1-2% worse compression for large blocks and
+ * 9-10% for small, redundant, blocks and >>20% better speed in both cases)
+ * In short: enable this for binary data, disable this for text data.
+ */
+#ifndef ULTRA_FAST
+# define ULTRA_FAST 1
+#endif
+
+#define STRICT_ALIGN 0
+#define USE_MEMCPY 1
+#define INIT_HTAB 0
+
+#include "lzf/lzf_c.c"
+#include "lzf/lzf_d.c"
+
+static struct suspend_plugin_ops lzf_compression_ops;
+static struct suspend_plugin_ops * next_driver;
+
+static void *compression_workspace = NULL;
+static u8 *local_buffer = NULL;
+static struct page * local_buffer_page = NULL;
+static u8 *page_buffer = NULL;
+static struct page * page_buffer_page = NULL;
+static unsigned int bufofs;
+
+static __nosavedata unsigned long bytes_in = 0, bytes_out = 0;
+
+/* allocate_compression_space
+ *
+ * Description:	Allocate space for use in [de]compressing our data.
+ *		Each call must have a matching call to free_memory.
+ * Returns:	Int: Zero if successful, -ENONEM otherwise.
+ */
+
+static inline int allocate_compression_space(void)
+{
+	BUG_ON(compression_workspace);
+
+	compression_workspace = vmalloc_32((1<<HLOG)*sizeof(char *));
+	if (!compression_workspace) {
+		printk(KERN_WARNING
+			"Failed to allocate %d bytes for lzf workspace\n",
+			(1<<HLOG)*sizeof(char *));
+		return -ENOMEM;
+	}
+	
+	return 0;
+}
+
+/* free_zlib_memory
+ *
+ * Description:	Frees memory allocated by the allocation routine (above).
+ */
+
+static inline void free_memory(void)
+{
+	if (!compression_workspace)
+		return;
+
+	vfree(compression_workspace);
+	compression_workspace = NULL;
+}
+
+/* ---- Local buffer management ---- */
+
+/* allocate_local_buffer
+ *
+ * Description:	Allocates a page of memory for buffering output.
+ * Returns:	Int: Zero if successful, -ENONEM otherwise.
+ */
+
+static int allocate_local_buffer(void)
+{
+	if (!local_buffer) {
+		local_buffer = (char *) get_zeroed_page(GFP_ATOMIC);
+	
+		if (!local_buffer) {
+			printk(KERN_ERR
+				"Failed to allocate the local buffer for "
+				"lzf compression driver.\n");
+			return -ENOMEM;
+		}
+		local_buffer_page = virt_to_page(local_buffer);
+	}
+
+	if (!page_buffer) {
+		page_buffer = (char *) get_zeroed_page(GFP_ATOMIC);
+	
+		if (!page_buffer) {
+			printk(KERN_ERR
+				"Failed to allocate the page buffer for "
+				"lzf compression driver.\n");
+			return -ENOMEM;
+		}
+		page_buffer_page = virt_to_page(page_buffer);
+	}
+
+	return 0;
+}
+
+/* free_local_buffer
+ *
+ * Description:	Frees memory allocated for buffering output.
+ */
+
+static inline void free_local_buffer(void)
+{
+	if (local_buffer)
+		free_pages((unsigned long) local_buffer, 0);
+
+	local_buffer = NULL;
+	local_buffer_page = NULL;
+
+	if (page_buffer)
+		free_pages((unsigned long) page_buffer, 0);
+
+	page_buffer = NULL;
+	page_buffer_page = NULL;
+}
+
+/* ---- Exported functions ---- */
+
+/* write_init()
+ *
+ * Description:	Allocate buffers and prepare to compress data.
+ * Arguments:	Stream_number:	Ignored.
+ * Returns:	Zero on success, -ENOMEM if unable to vmalloc.
+ */
+
+static int lzf_write_init(int stream_number)
+{
+	int result;
+	
+	next_driver = get_next_filter(&lzf_compression_ops);
+
+	if (!next_driver) {
+		printk("LZF Compression Driver: Argh! No one wants my output!");
+		return -ECHILD;
+	}
+
+	if ((result = allocate_compression_space()))
+		return result;
+	
+	if ((result = allocate_local_buffer()))
+		return result;
+
+	/* Only reset the stats if starting to write an image */
+	if (stream_number == 2)
+		bytes_in = bytes_out = 0;
+	
+	bufofs = 0;
+
+	return 0;
+}
+
+/* lzf_write()
+ *
+ * Description:	Helper function for write_chunk. Write the compressed data.
+ * Arguments:	u8*:		Output buffer to be written.
+ * 		unsigned int:	Length of buffer.
+ * Return:	int:		Result to be passed back to caller.
+ */
+
+static int lzf_write (u8 *buffer, unsigned int len)
+{
+	int ret;
+
+	bytes_out += len;
+
+	while (len + bufofs > PAGE_SIZE) {
+		unsigned int chunk = PAGE_SIZE - bufofs;
+		memcpy (local_buffer + bufofs, buffer, chunk);
+		buffer += chunk;
+		len -= chunk;
+		bufofs = 0;
+		if ((ret = next_driver->ops.filter.write_chunk(local_buffer_page)) < 0)
+			return ret;
+	}
+	memcpy (local_buffer + bufofs, buffer, len);
+	bufofs += len;
+	return 0;
+}
+
+/* lzf_write_chunk()
+ *
+ * Description:	Compress a page of data, buffering output and passing on
+ * 		filled pages to the next plugin in the pipeline.
+ * Arguments:	Buffer_page:	Pointer to a buffer of size PAGE_SIZE, 
+ * 				containing data to be compressed.
+ * Returns:	0 on success. Otherwise the error is that returned by later
+ * 		plugins, -ECHILD if we have a broken pipeline or -EPERM if
+ * 		zlib errs.
+ */
+
+static int lzf_write_chunk(struct page * buffer_page)
+{
+	int ret; 
+	u16 len;
+	char * buffer_start = kmap(buffer_page);
+	
+	bytes_in += PAGE_SIZE;
+
+	len = lzf_compress(buffer_start, PAGE_SIZE, page_buffer,
+			PAGE_SIZE - 3, compression_workspace);
+
+	if ((ret = lzf_write((u8 *)&len, 2)) >= 0) {
+		if (len) // some compression
+			ret = lzf_write(page_buffer, len);
+		else
+			ret = lzf_write(buffer_start, PAGE_SIZE);
+	}
+	kunmap(buffer_page);
+	return ret;
+}
+
+/* write_cleanup()
+ *
+ * Description: Write unflushed data and free workspace.
+ * Returns:	Result of writing last page.
+ */
+
+static int lzf_write_cleanup(void)
+{
+	int ret;
+	
+	ret = next_driver->ops.filter.write_chunk(local_buffer_page);
+
+	free_memory();
+	free_local_buffer();
+
+	return ret;
+}
+
+/* read_init()
+ *
+ * Description:	Prepare to read a new stream of data.
+ * Arguments:	int: Section of image about to be read.
+ * Returns:	int: Zero on success, error number otherwise.
+ */
+
+static int lzf_read_init(int stream_number)
+{
+	int result;
+
+	next_driver = get_next_filter(&lzf_compression_ops);
+
+	if (!next_driver) {
+		printk("LZF Compression Driver: Argh! No one wants "
+				"to feed me data!");
+		return -ECHILD;
+	}
+	
+	if ((result = allocate_local_buffer()))
+		return result;
+
+	bufofs = PAGE_SIZE;
+
+	return 0;
+}
+
+/* lzf_read()
+ *
+ * Description:	Read data into compression buffer.
+ * Arguments:	u8 *:		Address of the buffer.
+ * 		unsigned int:	Length
+ * Returns:	int:		Result of reading the image chunk.
+ */
+
+static int lzf_read (u8 * buffer, unsigned int len)
+{
+	int ret;
+
+	while (len + bufofs > PAGE_SIZE) {
+		unsigned int chunk = PAGE_SIZE - bufofs;
+		memcpy(buffer, local_buffer + bufofs, chunk);
+		buffer += chunk;
+		len -= chunk;
+		bufofs = 0;
+		if ((ret = next_driver->ops.filter.read_chunk(
+					local_buffer_page, SUSPEND_SYNC)) < 0) {
+			return ret;
+		}
+	}
+	memcpy (buffer, local_buffer + bufofs, len);
+	bufofs += len;
+	return 0;
+}
+
+/* lzf_read_chunk()
+ *
+ * Description:	Retrieve data from later plugins and decompress it until the
+ * 		input buffer is filled.
+ * Arguments:	Buffer_start: 	Pointer to a buffer of size PAGE_SIZE.
+ * 		Sync:		Whether the previous plugin (or core) wants its
+ * 				data synchronously.
+ * Returns:	Zero if successful. Error condition from me or from downstream
+ * 		on failure.
+ */
+
+static int lzf_read_chunk(struct page * buffer_page, int sync)
+{
+	int ret; 
+	u16 len;
+	char * buffer_start = kmap(buffer_page);
+
+	/* 
+	 * All our reads must be synchronous - we can't decompress
+	 * data that hasn't been read yet.
+	 */
+
+	if ((ret = lzf_read ((u8 *)&len, 2)) >= 0) {
+		if (len == 0) { // uncompressed
+			ret = lzf_read(buffer_start, PAGE_SIZE);
+		} else { // compressed
+			if ((ret = lzf_read(page_buffer, len)) >= 0) {
+				ret = lzf_decompress(page_buffer, len, buffer_start, PAGE_SIZE);
+				if (ret != PAGE_SIZE)
+					ret = -EPERM; // why EPERM??
+				else
+					ret = 0;
+			}
+		}
+	}
+	kunmap(buffer_page);
+	return ret;
+}
+
+/* read_cleanup()
+ *
+ * Description:	Clean up after reading part or all of a stream of data.
+ * Returns:	int: Always zero. Never fails.
+ */
+
+static int lzf_read_cleanup(void)
+{
+	free_local_buffer();
+	return 0;
+}
+
+/* lzf_print_debug_stats
+ *
+ * Description:	Print information to be recorded for debugging purposes into a
+ * 		buffer.
+ * Arguments:	buffer: Pointer to a buffer into which the debug info will be
+ * 			printed.
+ * 		size:	Size of the buffer.
+ * Returns:	Number of characters written to the buffer.
+ */
+
+static int lzf_print_debug_stats(char * buffer, int size)
+{
+	int pages_in = bytes_in >> PAGE_SHIFT, 
+		pages_out = bytes_out >> PAGE_SHIFT;
+	int len;
+	
+	/* Output the compression ratio achieved. */
+	len = suspend_snprintf(buffer, size, "- LZF Compressor enabled.\n");
+	if (pages_in)
+		len+= suspend_snprintf(buffer+len, size - len,
+		  "  Compressed %ld bytes into %ld (%d percent compression).\n",
+		  bytes_in, bytes_out, (pages_in - pages_out) * 100 / pages_in);
+	return len;
+}
+
+/* compression_memory_needed
+ *
+ * Description:	Tell the caller how much memory we need to operate during
+ * 		suspend/resume.
+ * Returns:	Unsigned long. Maximum number of bytes of memory required for
+ * 		operation.
+ */
+
+static unsigned long lzf_memory_needed(void)
+{
+	return PAGE_SIZE * 2 + (1<<HLOG)*sizeof(char *);
+}
+
+static unsigned long lzf_storage_needed(void)
+{
+	return 2 * sizeof(unsigned long);
+}
+
+/* lzf_save_config_info
+ *
+ * Description:	Save informaton needed when reloading the image at resume time.
+ * Arguments:	Buffer:		Pointer to a buffer of size PAGE_SIZE.
+ * Returns:	Number of bytes used for saving our data.
+ */
+
+static int lzf_save_config_info(char * buffer)
+{
+	*((unsigned long *) buffer) = bytes_in;
+	*((unsigned long *) (buffer + sizeof(unsigned long))) = bytes_out;
+	*((int *) (buffer + 2 * sizeof(unsigned long))) = expected_lzf_compression;
+	return 2 * sizeof(unsigned long) + sizeof(int);
+}
+
+/* lzf_load_config_info
+ *
+ * Description:	Reload information needed for decompressing the image at 
+ * 		resume time.
+ * Arguments:	Buffer:		Pointer to the start of the data.
+ *		Size:		Number of bytes that were saved.
+ */
+
+static void lzf_load_config_info(char * buffer, int size)
+{
+	if(size == 2 * sizeof(unsigned long) + sizeof(int)) {
+		bytes_in = *((unsigned long *) buffer);
+		bytes_out = *((unsigned long *) (buffer + sizeof(unsigned long)));
+		expected_lzf_compression = *((int *) (buffer + 2 * sizeof(unsigned long)));
+	} else
+		printk("Suspend LZF config info size mismatch: settings ignored.\n");
+	return;
+}
+
+/* lzf_get_expected_compression
+ * 
+ * Description:	Returns the expected ratio between data passed into this plugin
+ * 		and the amount of data output when writing.
+ * Returns:	100 if the plugin is disabled. Otherwise the value set by the
+ * 		user via our proc entry.
+ */
+
+static int lzf_get_expected_compression(void)
+{
+	return 100 - expected_lzf_compression;
+}
+
+/*
+ * data for our proc entries.
+ */
+
+static struct suspend_proc_data expected_compression_proc_data = {
+	.filename			= "expected_lzf_compression",
+	.permissions			= PROC_RW,
+	.type				= SUSPEND_PROC_DATA_INTEGER,
+	.data = {
+		.integer = {
+			.variable	= &expected_lzf_compression,
+			.minimum	= 0,
+			.maximum	= 99,
+		}
+	}
+};
+
+static struct suspend_proc_data disable_compression_proc_data = {
+	.filename			= "disable_lzf_compression",
+	.permissions			= PROC_RW,
+	.type				= SUSPEND_PROC_DATA_INTEGER,
+	.data = {
+		.integer = {
+			.variable	= &lzf_compression_ops.disabled,
+			.minimum	= 0,
+			.maximum	= 1,
+		}
+	}
+};
+
+/*
+ * Ops structure.
+ */
+
+static struct suspend_plugin_ops lzf_compression_ops = {
+	.type			= FILTER_PLUGIN,
+	.name			= "LZF Page Compressor",
+	.memory_needed 		= lzf_memory_needed,
+	.print_debug_info	= lzf_print_debug_stats,
+	.save_config_info	= lzf_save_config_info,
+	.load_config_info	= lzf_load_config_info,
+	.storage_needed		= lzf_storage_needed,
+	.ops = {
+		.filter = {
+			.write_init		= lzf_write_init,
+			.write_chunk		= lzf_write_chunk,
+			.write_cleanup		= lzf_write_cleanup,
+			.read_init		= lzf_read_init,
+			.read_chunk		= lzf_read_chunk,
+			.read_cleanup		= lzf_read_cleanup,
+			.expected_compression	= lzf_get_expected_compression,
+		}
+	}
+};
+
+/* ---- Registration ---- */
+
+static __init int lzf_load(void)
+{
+	int result;
+
+	if (!(result = suspend_register_plugin(&lzf_compression_ops))) {
+		printk("Software Suspend LZF Compression Driver registered.\n");
+		suspend_register_procfile(&expected_compression_proc_data);
+		suspend_register_procfile(&disable_compression_proc_data);
+	}
+	return result;
+}
+
+#ifdef MODULE
+static __exit void lzf_unload(void)
+{
+	printk("Software Suspend LZF Compression Driver unloading.\n");
+	suspend_unregister_procfile(&expected_compression_proc_data);
+	suspend_unregister_procfile(&disable_compression_proc_data);
+	suspend_unregister_plugin(&lzf_compression_ops);
+}
+
+
+module_init(lzf_load);
+module_exit(lzf_unload);
+MODULE_LICENSE("GPL");
+MODULE_AUTHOR("Marc Lehmann");
+MODULE_DESCRIPTION("LZF Compression support for Suspend2");
+#else
+late_initcall(lzf_load);
+#endif


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