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[Xen-changelog] [xen-unstable] x86/dom0: support bzip2 and lzma compressed bzImage payloads



# HG changeset patch
# User Keir Fraser <keir.fraser@xxxxxxxxxx>
# Date 1257753147 0
# Node ID c4630f8f69cc9579e7b011e56e3ceec8412c9671
# Parent  ac9d4ba48b8334f0adc3a928be4e48d2e6fdebd1
x86/dom0: support bzip2 and lzma compressed bzImage payloads

This matches functionality in the tools already supporting the same
for DomU-s.

Code taken from Linux 2.6.32-rc and adjusted as little as possible to
be usable in Xen.

The question is whether, particularly for non-Linux Dom0-s, plain ELF
images compressed by bzip2 or lzma should also be supported.

Signed-off-by: Jan Beulich <jbeulich@xxxxxxxxxx>
---
 xen/arch/x86/bzimage.c       |   60 ++-
 xen/common/Makefile          |    2 
 xen/common/bunzip2.c         |  726 +++++++++++++++++++++++++++++++++++++++++++
 xen/common/decompress.c      |   27 +
 xen/common/decompress.h      |   19 +
 xen/common/unlzma.c          |  647 ++++++++++++++++++++++++++++++++++++++
 xen/include/xen/decompress.h |   38 ++
 7 files changed, 1499 insertions(+), 20 deletions(-)

diff -r ac9d4ba48b83 -r c4630f8f69cc xen/arch/x86/bzimage.c
--- a/xen/arch/x86/bzimage.c    Thu Nov 05 12:00:58 2009 +0000
+++ b/xen/arch/x86/bzimage.c    Mon Nov 09 07:52:27 2009 +0000
@@ -4,6 +4,7 @@
 #include <xen/mm.h>
 #include <xen/string.h>
 #include <xen/types.h>
+#include <xen/decompress.h>
 #include <asm/bzimage.h>
 
 #define HEAPORDER 3
@@ -93,20 +94,30 @@ static __init void flush_window(void)
     outcnt = 0;
 }
 
-static __init int gzip_length(char *image, unsigned long image_len)
+static __init unsigned long output_length(char *image, unsigned long image_len)
 {
     return *(uint32_t *)&image[image_len - 4];
 }
 
-static  __init int perform_gunzip(char *output, char **_image_start, unsigned 
long *image_len)
-{
-    char *image = *_image_start;
+static __init int gzip_check(char *image, unsigned long image_len)
+{
+    unsigned char magic0, magic1;
+
+    if ( image_len < 2 )
+        return 0;
+
+    magic0 = (unsigned char)image[0];
+    magic1 = (unsigned char)image[1];
+
+    return (magic0 == 0x1f) && ((magic1 == 0x8b) || (magic1 == 0x9e));
+}
+
+static __init int perform_gunzip(char *output, char *image, unsigned long 
image_len)
+{
     int rc;
-    unsigned char magic0 = (unsigned char)image[0];
-    unsigned char magic1 = (unsigned char)image[1];
-
-    if ( magic0 != 0x1f || ( (magic1 != 0x8b) && (magic1 != 0x9e) ) )
-        return 0;
+
+    if ( !gzip_check(image, image_len) )
+        return 1;
 
     window = (unsigned char *)output;
 
@@ -114,7 +125,7 @@ static  __init int perform_gunzip(char *
     free_mem_end_ptr = free_mem_ptr + (PAGE_SIZE << HEAPORDER);
 
     inbuf = (unsigned char *)image;
-    insize = *image_len;
+    insize = image_len;
     inptr = 0;
 
     makecrc();
@@ -125,8 +136,6 @@ static  __init int perform_gunzip(char *
     }
     else
     {
-        *_image_start = (char *)window;
-        *image_len = gzip_length(image, *image_len);
         rc = 0;
     }
 
@@ -203,9 +212,12 @@ int __init bzimage_headroom(char *image_
     img = image_start + (hdr->setup_sects+1) * 512;
     img += hdr->payload_offset;
 
-    headroom = gzip_length(img, hdr->payload_length);
-    headroom += headroom >> 12; /* Add 8 bytes for every 32K input block */
-    headroom += (32768 + 18); /* Add 32K + 18 bytes of extra headroom */
+    headroom = output_length(img, hdr->payload_length);
+    if (gzip_check(img, hdr->payload_length)) {
+        headroom += headroom >> 12; /* Add 8 bytes for every 32K input block */
+        headroom += (32768 + 18); /* Add 32K + 18 bytes of extra headroom */
+    } else
+        headroom += hdr->payload_length;
     headroom = (headroom + 4095) & ~4095;
 
     return headroom;
@@ -215,6 +227,7 @@ int __init bzimage_parse(char *image_bas
 {
     struct setup_header *hdr = (struct setup_header *)(*image_start);
     int err = bzimage_check(hdr, *image_len);
+    unsigned long output_len;
 
     if (err < 1)
         return err;
@@ -224,11 +237,18 @@ int __init bzimage_parse(char *image_bas
     *image_start += (hdr->setup_sects+1) * 512;
     *image_start += hdr->payload_offset;
     *image_len = hdr->payload_length;
-
-    if ( (err = perform_gunzip(image_base, image_start, image_len)) < 0 )
-        return err;
-
-    return 0;
+    output_len = output_length(*image_start, *image_len);
+
+    if ( (err = perform_gunzip(image_base, *image_start, *image_len)) > 0 )
+        err = decompress(*image_start, *image_len, image_base);
+
+    if ( !err )
+    {
+        *image_start = image_base;
+        *image_len = output_len;
+    }
+
+    return err > 0 ? 0 : err;
 }
 
 /*
diff -r ac9d4ba48b83 -r c4630f8f69cc xen/common/Makefile
--- a/xen/common/Makefile       Thu Nov 05 12:00:58 2009 +0000
+++ b/xen/common/Makefile       Mon Nov 09 07:52:27 2009 +0000
@@ -35,6 +35,8 @@ obj-y += rbtree.o
 obj-y += rbtree.o
 obj-y += lzo.o
 
+obj-$(CONFIG_X86) += decompress.o bunzip2.o unlzma.o
+
 obj-$(perfc)       += perfc.o
 obj-$(crash_debug) += gdbstub.o
 obj-$(xenoprof)    += xenoprof.o
diff -r ac9d4ba48b83 -r c4630f8f69cc xen/common/bunzip2.c
--- /dev/null   Thu Jan 01 00:00:00 1970 +0000
+++ b/xen/common/bunzip2.c      Mon Nov 09 07:52:27 2009 +0000
@@ -0,0 +1,726 @@
+/* vi: set sw = 4 ts = 4: */
+/*     Small bzip2 deflate implementation, by Rob Landley (rob@xxxxxxxxxxx).
+
+       Based on bzip2 decompression code by Julian R Seward (jseward@xxxxxxx),
+       which also acknowledges contributions by Mike Burrows, David Wheeler,
+       Peter Fenwick, Alistair Moffat, Radford Neal, Ian H. Witten,
+       Robert Sedgewick, and Jon L. Bentley.
+
+       This code is licensed under the LGPLv2:
+               LGPL (http://www.gnu.org/copyleft/lgpl.html
+*/
+
+/*
+       Size and speed optimizations by Manuel Novoa III  (mjn3@xxxxxxxxxxxx).
+
+       More efficient reading of Huffman codes, a streamlined read_bunzip()
+       function, and various other tweaks.  In (limited) tests, approximately
+       20% faster than bzcat on x86 and about 10% faster on arm.
+
+       Note that about 2/3 of the time is spent in read_unzip() reversing
+       the Burrows-Wheeler transformation.  Much of that time is delay
+       resulting from cache misses.
+
+       I would ask that anyone benefiting from this work, especially those
+       using it in commercial products, consider making a donation to my local
+       non-profit hospice organization in the name of the woman I loved, who
+       passed away Feb. 12, 2003.
+
+               In memory of Toni W. Hagan
+
+               Hospice of Acadiana, Inc.
+               2600 Johnston St., Suite 200
+               Lafayette, LA 70503-3240
+
+               Phone (337) 232-1234 or 1-800-738-2226
+               Fax   (337) 232-1297
+
+               http://www.hospiceacadiana.com/
+
+       Manuel
+ */
+
+/*
+       Made it fit for running in Linux Kernel by Alain Knaff (alain@xxxxxxxx)
+*/
+
+#include "decompress.h"
+
+#ifndef INT_MAX
+#define INT_MAX 0x7fffffff
+#endif
+
+/* Constants for Huffman coding */
+#define MAX_GROUPS             6
+#define GROUP_SIZE             50      /* 64 would have been more efficient */
+#define MAX_HUFCODE_BITS       20      /* Longest Huffman code allowed */
+#define MAX_SYMBOLS            258     /* 256 literals + RUNA + RUNB */
+#define SYMBOL_RUNA            0
+#define SYMBOL_RUNB            1
+
+/* Status return values */
+#define RETVAL_OK                      0
+#define RETVAL_LAST_BLOCK              (-1)
+#define RETVAL_NOT_BZIP_DATA           (-2)
+#define RETVAL_UNEXPECTED_INPUT_EOF    (-3)
+#define RETVAL_UNEXPECTED_OUTPUT_EOF   (-4)
+#define RETVAL_DATA_ERROR              (-5)
+#define RETVAL_OUT_OF_MEMORY           (-6)
+#define RETVAL_OBSOLETE_INPUT          (-7)
+
+/* Other housekeeping constants */
+#define BZIP2_IOBUF_SIZE               4096
+
+/* This is what we know about each Huffman coding group */
+struct group_data {
+       /* We have an extra slot at the end of limit[] for a sentinal value. */
+       int limit[MAX_HUFCODE_BITS+1];
+       int base[MAX_HUFCODE_BITS];
+       int permute[MAX_SYMBOLS];
+       int minLen, maxLen;
+};
+
+/* Structure holding all the housekeeping data, including IO buffers and
+   memory that persists between calls to bunzip */
+struct bunzip_data {
+       /* State for interrupting output loop */
+       int writeCopies, writePos, writeRunCountdown, writeCount, writeCurrent;
+       /* I/O tracking data (file handles, buffers, positions, etc.) */
+       int (*fill)(void*, unsigned int);
+       int inbufCount, inbufPos /*, outbufPos*/;
+       unsigned char *inbuf /*,*outbuf*/;
+       unsigned int inbufBitCount, inbufBits;
+       /* The CRC values stored in the block header and calculated from the
+       data */
+       unsigned int crc32Table[256], headerCRC, totalCRC, writeCRC;
+       /* Intermediate buffer and its size (in bytes) */
+       unsigned int *dbuf, dbufSize;
+       /* These things are a bit too big to go on the stack */
+       unsigned char selectors[32768];         /* nSelectors = 15 bits */
+       struct group_data groups[MAX_GROUPS];   /* Huffman coding tables */
+       int io_error;                   /* non-zero if we have IO error */
+};
+
+
+/* Return the next nnn bits of input.  All reads from the compressed input
+   are done through this function.  All reads are big endian */
+static unsigned int INIT get_bits(struct bunzip_data *bd, char bits_wanted)
+{
+       unsigned int bits = 0;
+
+       /* If we need to get more data from the byte buffer, do so.
+          (Loop getting one byte at a time to enforce endianness and avoid
+          unaligned access.) */
+       while (bd->inbufBitCount < bits_wanted) {
+               /* If we need to read more data from file into byte buffer, do
+                  so */
+               if (bd->inbufPos == bd->inbufCount) {
+                       if (bd->io_error)
+                               return 0;
+                       bd->inbufCount = bd->fill(bd->inbuf, BZIP2_IOBUF_SIZE);
+                       if (bd->inbufCount <= 0) {
+                               bd->io_error = RETVAL_UNEXPECTED_INPUT_EOF;
+                               return 0;
+                       }
+                       bd->inbufPos = 0;
+               }
+               /* Avoid 32-bit overflow (dump bit buffer to top of output) */
+               if (bd->inbufBitCount >= 24) {
+                       bits = bd->inbufBits&((1 << bd->inbufBitCount)-1);
+                       bits_wanted -= bd->inbufBitCount;
+                       bits <<= bits_wanted;
+                       bd->inbufBitCount = 0;
+               }
+               /* Grab next 8 bits of input from buffer. */
+               bd->inbufBits = (bd->inbufBits << 8)|bd->inbuf[bd->inbufPos++];
+               bd->inbufBitCount += 8;
+       }
+       /* Calculate result */
+       bd->inbufBitCount -= bits_wanted;
+       bits |= (bd->inbufBits >> bd->inbufBitCount)&((1 << bits_wanted)-1);
+
+       return bits;
+}
+
+/* Unpacks the next block and sets up for the inverse burrows-wheeler step. */
+
+static int INIT get_next_block(struct bunzip_data *bd)
+{
+       struct group_data *hufGroup = NULL;
+       int *base = NULL;
+       int *limit = NULL;
+       int dbufCount, nextSym, dbufSize, groupCount, selector,
+               i, j, k, t, runPos, symCount, symTotal, nSelectors,
+               byteCount[256];
+       unsigned char uc, symToByte[256], mtfSymbol[256], *selectors;
+       unsigned int *dbuf, origPtr;
+
+       dbuf = bd->dbuf;
+       dbufSize = bd->dbufSize;
+       selectors = bd->selectors;
+
+       /* Read in header signature and CRC, then validate signature.
+          (last block signature means CRC is for whole file, return now) */
+       i = get_bits(bd, 24);
+       j = get_bits(bd, 24);
+       bd->headerCRC = get_bits(bd, 32);
+       if ((i == 0x177245) && (j == 0x385090))
+               return RETVAL_LAST_BLOCK;
+       if ((i != 0x314159) || (j != 0x265359))
+               return RETVAL_NOT_BZIP_DATA;
+       /* We can add support for blockRandomised if anybody complains.
+          There was some code for this in busybox 1.0.0-pre3, but nobody ever
+          noticed that it didn't actually work. */
+       if (get_bits(bd, 1))
+               return RETVAL_OBSOLETE_INPUT;
+       origPtr = get_bits(bd, 24);
+       if (origPtr > dbufSize)
+               return RETVAL_DATA_ERROR;
+       /* mapping table: if some byte values are never used (encoding things
+          like ascii text), the compression code removes the gaps to have fewer
+          symbols to deal with, and writes a sparse bitfield indicating which
+          values were present.  We make a translation table to convert the
+          symbols back to the corresponding bytes. */
+       t = get_bits(bd, 16);
+       symTotal = 0;
+       for (i = 0; i < 16; i++) {
+               if (t&(1 << (15-i))) {
+                       k = get_bits(bd, 16);
+                       for (j = 0; j < 16; j++)
+                               if (k&(1 << (15-j)))
+                                       symToByte[symTotal++] = (16*i)+j;
+               }
+       }
+       /* How many different Huffman coding groups does this block use? */
+       groupCount = get_bits(bd, 3);
+       if (groupCount < 2 || groupCount > MAX_GROUPS)
+               return RETVAL_DATA_ERROR;
+       /* nSelectors: Every GROUP_SIZE many symbols we select a new
+          Huffman coding group.  Read in the group selector list,
+          which is stored as MTF encoded bit runs.  (MTF = Move To
+          Front, as each value is used it's moved to the start of the
+          list.) */
+       nSelectors = get_bits(bd, 15);
+       if (!nSelectors)
+               return RETVAL_DATA_ERROR;
+       for (i = 0; i < groupCount; i++)
+               mtfSymbol[i] = i;
+       for (i = 0; i < nSelectors; i++) {
+               /* Get next value */
+               for (j = 0; get_bits(bd, 1); j++)
+                       if (j >= groupCount)
+                               return RETVAL_DATA_ERROR;
+               /* Decode MTF to get the next selector */
+               uc = mtfSymbol[j];
+               for (; j; j--)
+                       mtfSymbol[j] = mtfSymbol[j-1];
+               mtfSymbol[0] = selectors[i] = uc;
+       }
+       /* Read the Huffman coding tables for each group, which code
+          for symTotal literal symbols, plus two run symbols (RUNA,
+          RUNB) */
+       symCount = symTotal+2;
+       for (j = 0; j < groupCount; j++) {
+               unsigned char length[MAX_SYMBOLS], temp[MAX_HUFCODE_BITS+1];
+               int     minLen, maxLen, pp;
+               /* Read Huffman code lengths for each symbol.  They're
+                  stored in a way similar to mtf; record a starting
+                  value for the first symbol, and an offset from the
+                  previous value for everys symbol after that.
+                  (Subtracting 1 before the loop and then adding it
+                  back at the end is an optimization that makes the
+                  test inside the loop simpler: symbol length 0
+                  becomes negative, so an unsigned inequality catches
+                  it.) */
+               t = get_bits(bd, 5)-1;
+               for (i = 0; i < symCount; i++) {
+                       for (;;) {
+                               if (((unsigned)t) > (MAX_HUFCODE_BITS-1))
+                                       return RETVAL_DATA_ERROR;
+
+                               /* If first bit is 0, stop.  Else
+                                  second bit indicates whether to
+                                  increment or decrement the value.
+                                  Optimization: grab 2 bits and unget
+                                  the second if the first was 0. */
+
+                               k = get_bits(bd, 2);
+                               if (k < 2) {
+                                       bd->inbufBitCount++;
+                                       break;
+                               }
+                               /* Add one if second bit 1, else
+                                * subtract 1.  Avoids if/else */
+                               t += (((k+1)&2)-1);
+                       }
+                       /* Correct for the initial -1, to get the
+                        * final symbol length */
+                       length[i] = t+1;
+               }
+               /* Find largest and smallest lengths in this group */
+               minLen = maxLen = length[0];
+
+               for (i = 1; i < symCount; i++) {
+                       if (length[i] > maxLen)
+                               maxLen = length[i];
+                       else if (length[i] < minLen)
+                               minLen = length[i];
+               }
+
+               /* Calculate permute[], base[], and limit[] tables from
+                * length[].
+                *
+                * permute[] is the lookup table for converting
+                * Huffman coded symbols into decoded symbols.  base[]
+                * is the amount to subtract from the value of a
+                * Huffman symbol of a given length when using
+                * permute[].
+                *
+                * limit[] indicates the largest numerical value a
+                * symbol with a given number of bits can have.  This
+                * is how the Huffman codes can vary in length: each
+                * code with a value > limit[length] needs another
+                * bit.
+                */
+               hufGroup = bd->groups+j;
+               hufGroup->minLen = minLen;
+               hufGroup->maxLen = maxLen;
+               /* Note that minLen can't be smaller than 1, so we
+                  adjust the base and limit array pointers so we're
+                  not always wasting the first entry.  We do this
+                  again when using them (during symbol decoding).*/
+               base = hufGroup->base-1;
+               limit = hufGroup->limit-1;
+               /* Calculate permute[].  Concurently, initialize
+                * temp[] and limit[]. */
+               pp = 0;
+               for (i = minLen; i <= maxLen; i++) {
+                       temp[i] = limit[i] = 0;
+                       for (t = 0; t < symCount; t++)
+                               if (length[t] == i)
+                                       hufGroup->permute[pp++] = t;
+               }
+               /* Count symbols coded for at each bit length */
+               for (i = 0; i < symCount; i++)
+                       temp[length[i]]++;
+               /* Calculate limit[] (the largest symbol-coding value
+                *at each bit length, which is (previous limit <<
+                *1)+symbols at this level), and base[] (number of
+                *symbols to ignore at each bit length, which is limit
+                *minus the cumulative count of symbols coded for
+                *already). */
+               pp = t = 0;
+               for (i = minLen; i < maxLen; i++) {
+                       pp += temp[i];
+                       /* We read the largest possible symbol size
+                          and then unget bits after determining how
+                          many we need, and those extra bits could be
+                          set to anything.  (They're noise from
+                          future symbols.)  At each level we're
+                          really only interested in the first few
+                          bits, so here we set all the trailing
+                          to-be-ignored bits to 1 so they don't
+                          affect the value > limit[length]
+                          comparison. */
+                       limit[i] = (pp << (maxLen - i)) - 1;
+                       pp <<= 1;
+                       base[i+1] = pp-(t += temp[i]);
+               }
+               limit[maxLen+1] = INT_MAX; /* Sentinal value for
+                                           * reading next sym. */
+               limit[maxLen] = pp+temp[maxLen]-1;
+               base[minLen] = 0;
+       }
+       /* We've finished reading and digesting the block header.  Now
+          read this block's Huffman coded symbols from the file and
+          undo the Huffman coding and run length encoding, saving the
+          result into dbuf[dbufCount++] = uc */
+
+       /* Initialize symbol occurrence counters and symbol Move To
+        * Front table */
+       for (i = 0; i < 256; i++) {
+               byteCount[i] = 0;
+               mtfSymbol[i] = (unsigned char)i;
+       }
+       /* Loop through compressed symbols. */
+       runPos = dbufCount = symCount = selector = 0;
+       for (;;) {
+               /* Determine which Huffman coding group to use. */
+               if (!(symCount--)) {
+                       symCount = GROUP_SIZE-1;
+                       if (selector >= nSelectors)
+                               return RETVAL_DATA_ERROR;
+                       hufGroup = bd->groups+selectors[selector++];
+                       base = hufGroup->base-1;
+                       limit = hufGroup->limit-1;
+               }
+               /* Read next Huffman-coded symbol. */
+               /* Note: It is far cheaper to read maxLen bits and
+                  back up than it is to read minLen bits and then an
+                  additional bit at a time, testing as we go.
+                  Because there is a trailing last block (with file
+                  CRC), there is no danger of the overread causing an
+                  unexpected EOF for a valid compressed file.  As a
+                  further optimization, we do the read inline
+                  (falling back to a call to get_bits if the buffer
+                  runs dry).  The following (up to got_huff_bits:) is
+                  equivalent to j = get_bits(bd, hufGroup->maxLen);
+                */
+               while (bd->inbufBitCount < hufGroup->maxLen) {
+                       if (bd->inbufPos == bd->inbufCount) {
+                               j = get_bits(bd, hufGroup->maxLen);
+                               goto got_huff_bits;
+                       }
+                       bd->inbufBits =
+                               (bd->inbufBits << 8)|bd->inbuf[bd->inbufPos++];
+                       bd->inbufBitCount += 8;
+               };
+               bd->inbufBitCount -= hufGroup->maxLen;
+               j = (bd->inbufBits >> bd->inbufBitCount)&
+                       ((1 << hufGroup->maxLen)-1);
+got_huff_bits:
+               /* Figure how how many bits are in next symbol and
+                * unget extras */
+               i = hufGroup->minLen;
+               while (j > limit[i])
+                       ++i;
+               bd->inbufBitCount += (hufGroup->maxLen - i);
+               /* Huffman decode value to get nextSym (with bounds checking) */
+               if ((i > hufGroup->maxLen)
+                       || (((unsigned)(j = (j>>(hufGroup->maxLen-i))-base[i]))
+                               >= MAX_SYMBOLS))
+                       return RETVAL_DATA_ERROR;
+               nextSym = hufGroup->permute[j];
+               /* We have now decoded the symbol, which indicates
+                  either a new literal byte, or a repeated run of the
+                  most recent literal byte.  First, check if nextSym
+                  indicates a repeated run, and if so loop collecting
+                  how many times to repeat the last literal. */
+               if (((unsigned)nextSym) <= SYMBOL_RUNB) { /* RUNA or RUNB */
+                       /* If this is the start of a new run, zero out
+                        * counter */
+                       if (!runPos) {
+                               runPos = 1;
+                               t = 0;
+                       }
+                       /* Neat trick that saves 1 symbol: instead of
+                          or-ing 0 or 1 at each bit position, add 1
+                          or 2 instead.  For example, 1011 is 1 << 0
+                          + 1 << 1 + 2 << 2.  1010 is 2 << 0 + 2 << 1
+                          + 1 << 2.  You can make any bit pattern
+                          that way using 1 less symbol than the basic
+                          or 0/1 method (except all bits 0, which
+                          would use no symbols, but a run of length 0
+                          doesn't mean anything in this context).
+                          Thus space is saved. */
+                       t += (runPos << nextSym);
+                       /* +runPos if RUNA; +2*runPos if RUNB */
+
+                       runPos <<= 1;
+                       continue;
+               }
+               /* When we hit the first non-run symbol after a run,
+                  we now know how many times to repeat the last
+                  literal, so append that many copies to our buffer
+                  of decoded symbols (dbuf) now.  (The last literal
+                  used is the one at the head of the mtfSymbol
+                  array.) */
+               if (runPos) {
+                       runPos = 0;
+                       if (dbufCount+t >= dbufSize)
+                               return RETVAL_DATA_ERROR;
+
+                       uc = symToByte[mtfSymbol[0]];
+                       byteCount[uc] += t;
+                       while (t--)
+                               dbuf[dbufCount++] = uc;
+               }
+               /* Is this the terminating symbol? */
+               if (nextSym > symTotal)
+                       break;
+               /* At this point, nextSym indicates a new literal
+                  character.  Subtract one to get the position in the
+                  MTF array at which this literal is currently to be
+                  found.  (Note that the result can't be -1 or 0,
+                  because 0 and 1 are RUNA and RUNB.  But another
+                  instance of the first symbol in the mtf array,
+                  position 0, would have been handled as part of a
+                  run above.  Therefore 1 unused mtf position minus 2
+                  non-literal nextSym values equals -1.) */
+               if (dbufCount >= dbufSize)
+                       return RETVAL_DATA_ERROR;
+               i = nextSym - 1;
+               uc = mtfSymbol[i];
+               /* Adjust the MTF array.  Since we typically expect to
+                *move only a small number of symbols, and are bound
+                *by 256 in any case, using memmove here would
+                *typically be bigger and slower due to function call
+                *overhead and other assorted setup costs. */
+               do {
+                       mtfSymbol[i] = mtfSymbol[i-1];
+               } while (--i);
+               mtfSymbol[0] = uc;
+               uc = symToByte[uc];
+               /* We have our literal byte.  Save it into dbuf. */
+               byteCount[uc]++;
+               dbuf[dbufCount++] = (unsigned int)uc;
+       }
+       /* At this point, we've read all the Huffman-coded symbols
+          (and repeated runs) for this block from the input stream,
+          and decoded them into the intermediate buffer.  There are
+          dbufCount many decoded bytes in dbuf[].  Now undo the
+          Burrows-Wheeler transform on dbuf.  See
+          http://dogma.net/markn/articles/bwt/bwt.htm
+        */
+       /* Turn byteCount into cumulative occurrence counts of 0 to n-1. */
+       j = 0;
+       for (i = 0; i < 256; i++) {
+               k = j+byteCount[i];
+               byteCount[i] = j;
+               j = k;
+       }
+       /* Figure out what order dbuf would be in if we sorted it. */
+       for (i = 0; i < dbufCount; i++) {
+               uc = (unsigned char)(dbuf[i] & 0xff);
+               dbuf[byteCount[uc]] |= (i << 8);
+               byteCount[uc]++;
+       }
+       /* Decode first byte by hand to initialize "previous" byte.
+          Note that it doesn't get output, and if the first three
+          characters are identical it doesn't qualify as a run (hence
+          writeRunCountdown = 5). */
+       if (dbufCount) {
+               if (origPtr >= dbufCount)
+                       return RETVAL_DATA_ERROR;
+               bd->writePos = dbuf[origPtr];
+               bd->writeCurrent = (unsigned char)(bd->writePos&0xff);
+               bd->writePos >>= 8;
+               bd->writeRunCountdown = 5;
+       }
+       bd->writeCount = dbufCount;
+
+       return RETVAL_OK;
+}
+
+/* Undo burrows-wheeler transform on intermediate buffer to produce output.
+   If start_bunzip was initialized with out_fd =-1, then up to len bytes of
+   data are written to outbuf.  Return value is number of bytes written or
+   error (all errors are negative numbers).  If out_fd!=-1, outbuf and len
+   are ignored, data is written to out_fd and return is RETVAL_OK or error.
+*/
+
+static int INIT read_bunzip(struct bunzip_data *bd, unsigned char *outbuf, int 
len)
+{
+       const unsigned int *dbuf;
+       int pos, xcurrent, previous, gotcount;
+
+       /* If last read was short due to end of file, return last block now */
+       if (bd->writeCount < 0)
+               return bd->writeCount;
+
+       gotcount = 0;
+       dbuf = bd->dbuf;
+       pos = bd->writePos;
+       xcurrent = bd->writeCurrent;
+
+       /* We will always have pending decoded data to write into the output
+          buffer unless this is the very first call (in which case we haven't
+          Huffman-decoded a block into the intermediate buffer yet). */
+
+       if (bd->writeCopies) {
+               /* Inside the loop, writeCopies means extra copies (beyond 1) */
+               --bd->writeCopies;
+               /* Loop outputting bytes */
+               for (;;) {
+                       /* If the output buffer is full, snapshot
+                        * state and return */
+                       if (gotcount >= len) {
+                               bd->writePos = pos;
+                               bd->writeCurrent = xcurrent;
+                               bd->writeCopies++;
+                               return len;
+                       }
+                       /* Write next byte into output buffer, updating CRC */
+                       outbuf[gotcount++] = xcurrent;
+                       bd->writeCRC = (((bd->writeCRC) << 8)
+                               ^bd->crc32Table[((bd->writeCRC) >> 24)
+                               ^xcurrent]);
+                       /* Loop now if we're outputting multiple
+                        * copies of this byte */
+                       if (bd->writeCopies) {
+                               --bd->writeCopies;
+                               continue;
+                       }
+decode_next_byte:
+                       if (!bd->writeCount--)
+                               break;
+                       /* Follow sequence vector to undo
+                        * Burrows-Wheeler transform */
+                       previous = xcurrent;
+                       pos = dbuf[pos];
+                       xcurrent = pos&0xff;
+                       pos >>= 8;
+                       /* After 3 consecutive copies of the same
+                          byte, the 4th is a repeat count.  We count
+                          down from 4 instead *of counting up because
+                          testing for non-zero is faster */
+                       if (--bd->writeRunCountdown) {
+                               if (xcurrent != previous)
+                                       bd->writeRunCountdown = 4;
+                       } else {
+                               /* We have a repeated run, this byte
+                                * indicates the count */
+                               bd->writeCopies = xcurrent;
+                               xcurrent = previous;
+                               bd->writeRunCountdown = 5;
+                               /* Sometimes there are just 3 bytes
+                                * (run length 0) */
+                               if (!bd->writeCopies)
+                                       goto decode_next_byte;
+                               /* Subtract the 1 copy we'd output
+                                * anyway to get extras */
+                               --bd->writeCopies;
+                       }
+               }
+               /* Decompression of this block completed successfully */
+               bd->writeCRC = ~bd->writeCRC;
+               bd->totalCRC = ((bd->totalCRC << 1) |
+                               (bd->totalCRC >> 31)) ^ bd->writeCRC;
+               /* If this block had a CRC error, force file level CRC error. */
+               if (bd->writeCRC != bd->headerCRC) {
+                       bd->totalCRC = bd->headerCRC+1;
+                       return RETVAL_LAST_BLOCK;
+               }
+       }
+
+       /* Refill the intermediate buffer by Huffman-decoding next
+        * block of input */
+       /* (previous is just a convenient unused temp variable here) */
+       previous = get_next_block(bd);
+       if (previous) {
+               bd->writeCount = previous;
+               return (previous != RETVAL_LAST_BLOCK) ? previous : gotcount;
+       }
+       bd->writeCRC = 0xffffffffUL;
+       pos = bd->writePos;
+       xcurrent = bd->writeCurrent;
+       goto decode_next_byte;
+}
+
+static int INIT nofill(void *buf, unsigned int len)
+{
+       return -1;
+}
+
+/* Allocate the structure, read file header.  If in_fd ==-1, inbuf must contain
+   a complete bunzip file (len bytes long).  If in_fd!=-1, inbuf and len are
+   ignored, and data is read from file handle into temporary buffer. */
+static int INIT start_bunzip(struct bunzip_data **bdp, void *inbuf, int len,
+                            int (*fill)(void*, unsigned int))
+{
+       struct bunzip_data *bd;
+       unsigned int i, j, c;
+       const unsigned int BZh0 =
+               (((unsigned int)'B') << 24)+(((unsigned int)'Z') << 16)
+               +(((unsigned int)'h') << 8)+(unsigned int)'0';
+
+       /* Figure out how much data to allocate */
+       i = sizeof(struct bunzip_data);
+
+       /* Allocate bunzip_data.  Most fields initialize to zero. */
+       bd = *bdp = malloc(i);
+       memset(bd, 0, sizeof(struct bunzip_data));
+       /* Setup input buffer */
+       bd->inbuf = inbuf;
+       bd->inbufCount = len;
+       if (fill != NULL)
+               bd->fill = fill;
+       else
+               bd->fill = nofill;
+
+       /* Init the CRC32 table (big endian) */
+       for (i = 0; i < 256; i++) {
+               c = i << 24;
+               for (j = 8; j; j--)
+                       c = c&0x80000000 ? (c << 1)^0x04c11db7 : (c << 1);
+               bd->crc32Table[i] = c;
+       }
+
+       /* Ensure that file starts with "BZh['1'-'9']." */
+       i = get_bits(bd, 32);
+       if (((unsigned int)(i-BZh0-1)) >= 9)
+               return RETVAL_NOT_BZIP_DATA;
+
+       /* Fourth byte (ascii '1'-'9'), indicates block size in units of 100k of
+          uncompressed data.  Allocate intermediate buffer for block. */
+       bd->dbufSize = 100000*(i-BZh0);
+
+       bd->dbuf = large_malloc(bd->dbufSize * sizeof(int));
+       return RETVAL_OK;
+}
+
+/* Example usage: decompress src_fd to dst_fd.  (Stops at end of bzip2 data,
+   not end of file.) */
+STATIC int INIT bunzip2(unsigned char *buf, unsigned int len,
+                       int(*fill)(void*, unsigned int),
+                       int(*flush)(void*, unsigned int),
+                       unsigned char *outbuf,
+                       unsigned int *pos,
+                       void(*error_fn)(const char *x))
+{
+       struct bunzip_data *bd;
+       int i = -1;
+       unsigned char *inbuf;
+
+       set_error_fn(error_fn);
+       if (flush)
+               outbuf = malloc(BZIP2_IOBUF_SIZE);
+
+       if (!outbuf) {
+               error("Could not allocate output bufer");
+               return -1;
+       }
+       if (buf)
+               inbuf = buf;
+       else
+               inbuf = malloc(BZIP2_IOBUF_SIZE);
+       if (!inbuf) {
+               error("Could not allocate input bufer");
+               goto exit_0;
+       }
+       i = start_bunzip(&bd, inbuf, len, fill);
+       if (!i) {
+               for (;;) {
+                       i = read_bunzip(bd, outbuf, BZIP2_IOBUF_SIZE);
+                       if (i <= 0)
+                               break;
+                       if (!flush)
+                               outbuf += i;
+                       else
+                               if (i != flush(outbuf, i)) {
+                                       i = RETVAL_UNEXPECTED_OUTPUT_EOF;
+                                       break;
+                               }
+               }
+       }
+       /* Check CRC and release memory */
+       if (i == RETVAL_LAST_BLOCK) {
+               if (bd->headerCRC != bd->totalCRC)
+                       error("Data integrity error when decompressing.");
+               else
+                       i = RETVAL_OK;
+       } else if (i == RETVAL_UNEXPECTED_OUTPUT_EOF) {
+               error("Compressed file ends unexpectedly");
+       }
+       if (bd->dbuf)
+               large_free(bd->dbuf);
+       if (pos)
+               *pos = bd->inbufPos;
+       free(bd);
+       if (!buf)
+               free(inbuf);
+exit_0:
+       if (flush)
+               free(outbuf);
+       return i;
+}
diff -r ac9d4ba48b83 -r c4630f8f69cc xen/common/decompress.c
--- /dev/null   Thu Jan 01 00:00:00 1970 +0000
+++ b/xen/common/decompress.c   Mon Nov 09 07:52:27 2009 +0000
@@ -0,0 +1,27 @@
+#include <xen/config.h>
+#include <xen/init.h>
+#include <xen/lib.h>
+#include <xen/string.h>
+#include <xen/decompress.h>
+
+static void __init error(const char *msg)
+{
+    printk("%s\n", msg);
+}
+
+int __init decompress(void *inbuf, unsigned int len, void *outbuf)
+{
+#if 0 /* Not needed here yet. */
+    if ( len >= 2 &&
+         (!memcmp(inbuf, "\037\213", 2) || !memcmp(inbuf, "\037\236", 2)) )
+        return gunzip(inbuf, len, NULL, NULL, outbuf, NULL, error);
+#endif
+
+    if ( len >= 3 && !memcmp(inbuf, "\x42\x5a\x68", 3) )
+        return bunzip2(inbuf, len, NULL, NULL, outbuf, NULL, error);
+
+    if ( len >= 2 && !memcmp(inbuf, "\135\000", 2) )
+        return unlzma(inbuf, len, NULL, NULL, outbuf, NULL, error);
+
+    return 1;
+}
diff -r ac9d4ba48b83 -r c4630f8f69cc xen/common/decompress.h
--- /dev/null   Thu Jan 01 00:00:00 1970 +0000
+++ b/xen/common/decompress.h   Mon Nov 09 07:52:27 2009 +0000
@@ -0,0 +1,19 @@
+#include <xen/config.h>
+#include <xen/cache.h>
+#include <xen/decompress.h>
+#include <xen/init.h>
+#include <xen/string.h>
+#include <xen/types.h>
+#include <xen/xmalloc.h>
+
+#define STATIC
+#define INIT __init
+
+static void(*__initdata error)(const char *);
+#define set_error_fn(x) error = x;
+
+#define malloc xmalloc_bytes
+#define free xfree
+
+#define large_malloc xmalloc_bytes
+#define large_free xfree
diff -r ac9d4ba48b83 -r c4630f8f69cc xen/common/unlzma.c
--- /dev/null   Thu Jan 01 00:00:00 1970 +0000
+++ b/xen/common/unlzma.c       Mon Nov 09 07:52:27 2009 +0000
@@ -0,0 +1,647 @@
+/* Lzma decompressor for Linux kernel. Shamelessly snarfed
+ * from busybox 1.1.1
+ *
+ * Linux kernel adaptation
+ * Copyright (C) 2006  Alain < alain@xxxxxxxx >
+ *
+ * Based on small lzma deflate implementation/Small range coder
+ * implementation for lzma.
+ * Copyright (C) 2006  Aurelien Jacobs < aurel@xxxxxxxxxx >
+ *
+ * Based on LzmaDecode.c from the LZMA SDK 4.22 (http://www.7-zip.org/)
+ * Copyright (C) 1999-2005  Igor Pavlov
+ *
+ * Copyrights of the parts, see headers below.
+ *
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 2.1 of the License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this library; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
+ */
+
+#include "decompress.h"
+
+#define        MIN(a, b) (((a) < (b)) ? (a) : (b))
+
+static long long INIT read_int(unsigned char *ptr, int size)
+{
+       int i;
+       long long ret = 0;
+
+       for (i = 0; i < size; i++)
+               ret = (ret << 8) | ptr[size-i-1];
+       return ret;
+}
+
+#define ENDIAN_CONVERT(x) \
+  x = (typeof(x))read_int((unsigned char *)&x, sizeof(x))
+
+
+/* Small range coder implementation for lzma.
+ * Copyright (C) 2006  Aurelien Jacobs < aurel@xxxxxxxxxx >
+ *
+ * Based on LzmaDecode.c from the LZMA SDK 4.22 (http://www.7-zip.org/)
+ * Copyright (c) 1999-2005  Igor Pavlov
+ */
+
+#include <xen/compiler.h>
+
+#define LZMA_IOBUF_SIZE        0x10000
+
+struct rc {
+       int (*fill)(void*, unsigned int);
+       uint8_t *ptr;
+       uint8_t *buffer;
+       uint8_t *buffer_end;
+       int buffer_size;
+       uint32_t code;
+       uint32_t range;
+       uint32_t bound;
+};
+
+
+#define RC_TOP_BITS 24
+#define RC_MOVE_BITS 5
+#define RC_MODEL_TOTAL_BITS 11
+
+
+static int nofill(void *buffer, unsigned int len)
+{
+       return -1;
+}
+
+/* Called twice: once at startup and once in rc_normalize() */
+static void INIT rc_read(struct rc *rc)
+{
+       rc->buffer_size = rc->fill((char *)rc->buffer, LZMA_IOBUF_SIZE);
+       if (rc->buffer_size <= 0)
+               error("unexpected EOF");
+       rc->ptr = rc->buffer;
+       rc->buffer_end = rc->buffer + rc->buffer_size;
+}
+
+/* Called once */
+static inline void INIT rc_init(struct rc *rc,
+                                      int (*fill)(void*, unsigned int),
+                                      unsigned char *buffer, int buffer_size)
+{
+       if (fill)
+               rc->fill = fill;
+       else
+               rc->fill = nofill;
+       rc->buffer = (uint8_t *)buffer;
+       rc->buffer_size = buffer_size;
+       rc->buffer_end = rc->buffer + rc->buffer_size;
+       rc->ptr = rc->buffer;
+
+       rc->code = 0;
+       rc->range = 0xFFFFFFFF;
+}
+
+static inline void INIT rc_init_code(struct rc *rc)
+{
+       int i;
+
+       for (i = 0; i < 5; i++) {
+               if (rc->ptr >= rc->buffer_end)
+                       rc_read(rc);
+               rc->code = (rc->code << 8) | *rc->ptr++;
+       }
+}
+
+
+/* Called once. TODO: bb_maybe_free() */
+static inline void INIT rc_free(struct rc *rc)
+{
+       free(rc->buffer);
+}
+
+/* Called twice, but one callsite is in inline'd rc_is_bit_0_helper() */
+static void INIT rc_do_normalize(struct rc *rc)
+{
+       if (rc->ptr >= rc->buffer_end)
+               rc_read(rc);
+       rc->range <<= 8;
+       rc->code = (rc->code << 8) | *rc->ptr++;
+}
+static inline void INIT rc_normalize(struct rc *rc)
+{
+       if (rc->range < (1 << RC_TOP_BITS))
+               rc_do_normalize(rc);
+}
+
+/* Called 9 times */
+/* Why rc_is_bit_0_helper exists?
+ *Because we want to always expose (rc->code < rc->bound) to optimizer
+ */
+static inline uint32_t INIT rc_is_bit_0_helper(struct rc *rc, uint16_t *p)
+{
+       rc_normalize(rc);
+       rc->bound = *p * (rc->range >> RC_MODEL_TOTAL_BITS);
+       return rc->bound;
+}
+static inline int INIT rc_is_bit_0(struct rc *rc, uint16_t *p)
+{
+       uint32_t t = rc_is_bit_0_helper(rc, p);
+       return rc->code < t;
+}
+
+/* Called ~10 times, but very small, thus inlined */
+static inline void INIT rc_update_bit_0(struct rc *rc, uint16_t *p)
+{
+       rc->range = rc->bound;
+       *p += ((1 << RC_MODEL_TOTAL_BITS) - *p) >> RC_MOVE_BITS;
+}
+static inline void rc_update_bit_1(struct rc *rc, uint16_t *p)
+{
+       rc->range -= rc->bound;
+       rc->code -= rc->bound;
+       *p -= *p >> RC_MOVE_BITS;
+}
+
+/* Called 4 times in unlzma loop */
+static int INIT rc_get_bit(struct rc *rc, uint16_t *p, int *symbol)
+{
+       if (rc_is_bit_0(rc, p)) {
+               rc_update_bit_0(rc, p);
+               *symbol *= 2;
+               return 0;
+       } else {
+               rc_update_bit_1(rc, p);
+               *symbol = *symbol * 2 + 1;
+               return 1;
+       }
+}
+
+/* Called once */
+static inline int INIT rc_direct_bit(struct rc *rc)
+{
+       rc_normalize(rc);
+       rc->range >>= 1;
+       if (rc->code >= rc->range) {
+               rc->code -= rc->range;
+               return 1;
+       }
+       return 0;
+}
+
+/* Called twice */
+static inline void INIT
+rc_bit_tree_decode(struct rc *rc, uint16_t *p, int num_levels, int *symbol)
+{
+       int i = num_levels;
+
+       *symbol = 1;
+       while (i--)
+               rc_get_bit(rc, p + *symbol, symbol);
+       *symbol -= 1 << num_levels;
+}
+
+
+/*
+ * Small lzma deflate implementation.
+ * Copyright (C) 2006  Aurelien Jacobs < aurel@xxxxxxxxxx >
+ *
+ * Based on LzmaDecode.c from the LZMA SDK 4.22 (http://www.7-zip.org/)
+ * Copyright (C) 1999-2005  Igor Pavlov
+ */
+
+
+struct lzma_header {
+       uint8_t pos;
+       uint32_t dict_size;
+       uint64_t dst_size;
+} __attribute__ ((packed)) ;
+
+
+#define LZMA_BASE_SIZE 1846
+#define LZMA_LIT_SIZE 768
+
+#define LZMA_NUM_POS_BITS_MAX 4
+
+#define LZMA_LEN_NUM_LOW_BITS 3
+#define LZMA_LEN_NUM_MID_BITS 3
+#define LZMA_LEN_NUM_HIGH_BITS 8
+
+#define LZMA_LEN_CHOICE 0
+#define LZMA_LEN_CHOICE_2 (LZMA_LEN_CHOICE + 1)
+#define LZMA_LEN_LOW (LZMA_LEN_CHOICE_2 + 1)
+#define LZMA_LEN_MID (LZMA_LEN_LOW \
+                     + (1 << (LZMA_NUM_POS_BITS_MAX + LZMA_LEN_NUM_LOW_BITS)))
+#define LZMA_LEN_HIGH (LZMA_LEN_MID \
+                      +(1 << (LZMA_NUM_POS_BITS_MAX + LZMA_LEN_NUM_MID_BITS)))
+#define LZMA_NUM_LEN_PROBS (LZMA_LEN_HIGH + (1 << LZMA_LEN_NUM_HIGH_BITS))
+
+#define LZMA_NUM_STATES 12
+#define LZMA_NUM_LIT_STATES 7
+
+#define LZMA_START_POS_MODEL_INDEX 4
+#define LZMA_END_POS_MODEL_INDEX 14
+#define LZMA_NUM_FULL_DISTANCES (1 << (LZMA_END_POS_MODEL_INDEX >> 1))
+
+#define LZMA_NUM_POS_SLOT_BITS 6
+#define LZMA_NUM_LEN_TO_POS_STATES 4
+
+#define LZMA_NUM_ALIGN_BITS 4
+
+#define LZMA_MATCH_MIN_LEN 2
+
+#define LZMA_IS_MATCH 0
+#define LZMA_IS_REP (LZMA_IS_MATCH + (LZMA_NUM_STATES << 
LZMA_NUM_POS_BITS_MAX))
+#define LZMA_IS_REP_G0 (LZMA_IS_REP + LZMA_NUM_STATES)
+#define LZMA_IS_REP_G1 (LZMA_IS_REP_G0 + LZMA_NUM_STATES)
+#define LZMA_IS_REP_G2 (LZMA_IS_REP_G1 + LZMA_NUM_STATES)
+#define LZMA_IS_REP_0_LONG (LZMA_IS_REP_G2 + LZMA_NUM_STATES)
+#define LZMA_POS_SLOT (LZMA_IS_REP_0_LONG \
+                      + (LZMA_NUM_STATES << LZMA_NUM_POS_BITS_MAX))
+#define LZMA_SPEC_POS (LZMA_POS_SLOT \
+                      +(LZMA_NUM_LEN_TO_POS_STATES << LZMA_NUM_POS_SLOT_BITS))
+#define LZMA_ALIGN (LZMA_SPEC_POS \
+                   + LZMA_NUM_FULL_DISTANCES - LZMA_END_POS_MODEL_INDEX)
+#define LZMA_LEN_CODER (LZMA_ALIGN + (1 << LZMA_NUM_ALIGN_BITS))
+#define LZMA_REP_LEN_CODER (LZMA_LEN_CODER + LZMA_NUM_LEN_PROBS)
+#define LZMA_LITERAL (LZMA_REP_LEN_CODER + LZMA_NUM_LEN_PROBS)
+
+
+struct writer {
+       uint8_t *buffer;
+       uint8_t previous_byte;
+       size_t buffer_pos;
+       int bufsize;
+       size_t global_pos;
+       int(*flush)(void*, unsigned int);
+       struct lzma_header *header;
+};
+
+struct cstate {
+       int state;
+       uint32_t rep0, rep1, rep2, rep3;
+};
+
+static inline size_t INIT get_pos(struct writer *wr)
+{
+       return
+               wr->global_pos + wr->buffer_pos;
+}
+
+static inline uint8_t INIT peek_old_byte(struct writer *wr,
+                                               uint32_t offs)
+{
+       if (!wr->flush) {
+               int32_t pos;
+               while (offs > wr->header->dict_size)
+                       offs -= wr->header->dict_size;
+               pos = wr->buffer_pos - offs;
+               return wr->buffer[pos];
+       } else {
+               uint32_t pos = wr->buffer_pos - offs;
+               while (pos >= wr->header->dict_size)
+                       pos += wr->header->dict_size;
+               return wr->buffer[pos];
+       }
+
+}
+
+static inline void INIT write_byte(struct writer *wr, uint8_t byte)
+{
+       wr->buffer[wr->buffer_pos++] = wr->previous_byte = byte;
+       if (wr->flush && wr->buffer_pos == wr->header->dict_size) {
+               wr->buffer_pos = 0;
+               wr->global_pos += wr->header->dict_size;
+               wr->flush((char *)wr->buffer, wr->header->dict_size);
+       }
+}
+
+
+static inline void INIT copy_byte(struct writer *wr, uint32_t offs)
+{
+       write_byte(wr, peek_old_byte(wr, offs));
+}
+
+static inline void INIT copy_bytes(struct writer *wr,
+                                        uint32_t rep0, int len)
+{
+       do {
+               copy_byte(wr, rep0);
+               len--;
+       } while (len != 0 && wr->buffer_pos < wr->header->dst_size);
+}
+
+static inline void INIT process_bit0(struct writer *wr, struct rc *rc,
+                                    struct cstate *cst, uint16_t *p,
+                                    int pos_state, uint16_t *prob,
+                                    int lc, uint32_t literal_pos_mask) {
+       int mi = 1;
+       rc_update_bit_0(rc, prob);
+       prob = (p + LZMA_LITERAL +
+               (LZMA_LIT_SIZE
+                * (((get_pos(wr) & literal_pos_mask) << lc)
+                   + (wr->previous_byte >> (8 - lc))))
+               );
+
+       if (cst->state >= LZMA_NUM_LIT_STATES) {
+               int match_byte = peek_old_byte(wr, cst->rep0);
+               do {
+                       int bit;
+                       uint16_t *prob_lit;
+
+                       match_byte <<= 1;
+                       bit = match_byte & 0x100;
+                       prob_lit = prob + 0x100 + bit + mi;
+                       if (rc_get_bit(rc, prob_lit, &mi)) {
+                               if (!bit)
+                                       break;
+                       } else {
+                               if (bit)
+                                       break;
+                       }
+               } while (mi < 0x100);
+       }
+       while (mi < 0x100) {
+               uint16_t *prob_lit = prob + mi;
+               rc_get_bit(rc, prob_lit, &mi);
+       }
+       write_byte(wr, mi);
+       if (cst->state < 4)
+               cst->state = 0;
+       else if (cst->state < 10)
+               cst->state -= 3;
+       else
+               cst->state -= 6;
+}
+
+static inline void INIT process_bit1(struct writer *wr, struct rc *rc,
+                                           struct cstate *cst, uint16_t *p,
+                                           int pos_state, uint16_t *prob) {
+  int offset;
+       uint16_t *prob_len;
+       int num_bits;
+       int len;
+
+       rc_update_bit_1(rc, prob);
+       prob = p + LZMA_IS_REP + cst->state;
+       if (rc_is_bit_0(rc, prob)) {
+               rc_update_bit_0(rc, prob);
+               cst->rep3 = cst->rep2;
+               cst->rep2 = cst->rep1;
+               cst->rep1 = cst->rep0;
+               cst->state = cst->state < LZMA_NUM_LIT_STATES ? 0 : 3;
+               prob = p + LZMA_LEN_CODER;
+       } else {
+               rc_update_bit_1(rc, prob);
+               prob = p + LZMA_IS_REP_G0 + cst->state;
+               if (rc_is_bit_0(rc, prob)) {
+                       rc_update_bit_0(rc, prob);
+                       prob = (p + LZMA_IS_REP_0_LONG
+                               + (cst->state <<
+                                  LZMA_NUM_POS_BITS_MAX) +
+                               pos_state);
+                       if (rc_is_bit_0(rc, prob)) {
+                               rc_update_bit_0(rc, prob);
+
+                               cst->state = cst->state < LZMA_NUM_LIT_STATES ?
+                                       9 : 11;
+                               copy_byte(wr, cst->rep0);
+                               return;
+                       } else {
+                               rc_update_bit_1(rc, prob);
+                       }
+               } else {
+                       uint32_t distance;
+
+                       rc_update_bit_1(rc, prob);
+                       prob = p + LZMA_IS_REP_G1 + cst->state;
+                       if (rc_is_bit_0(rc, prob)) {
+                               rc_update_bit_0(rc, prob);
+                               distance = cst->rep1;
+                       } else {
+                               rc_update_bit_1(rc, prob);
+                               prob = p + LZMA_IS_REP_G2 + cst->state;
+                               if (rc_is_bit_0(rc, prob)) {
+                                       rc_update_bit_0(rc, prob);
+                                       distance = cst->rep2;
+                               } else {
+                                       rc_update_bit_1(rc, prob);
+                                       distance = cst->rep3;
+                                       cst->rep3 = cst->rep2;
+                               }
+                               cst->rep2 = cst->rep1;
+                       }
+                       cst->rep1 = cst->rep0;
+                       cst->rep0 = distance;
+               }
+               cst->state = cst->state < LZMA_NUM_LIT_STATES ? 8 : 11;
+               prob = p + LZMA_REP_LEN_CODER;
+       }
+
+       prob_len = prob + LZMA_LEN_CHOICE;
+       if (rc_is_bit_0(rc, prob_len)) {
+               rc_update_bit_0(rc, prob_len);
+               prob_len = (prob + LZMA_LEN_LOW
+                           + (pos_state <<
+                              LZMA_LEN_NUM_LOW_BITS));
+               offset = 0;
+               num_bits = LZMA_LEN_NUM_LOW_BITS;
+       } else {
+               rc_update_bit_1(rc, prob_len);
+               prob_len = prob + LZMA_LEN_CHOICE_2;
+               if (rc_is_bit_0(rc, prob_len)) {
+                       rc_update_bit_0(rc, prob_len);
+                       prob_len = (prob + LZMA_LEN_MID
+                                   + (pos_state <<
+                                      LZMA_LEN_NUM_MID_BITS));
+                       offset = 1 << LZMA_LEN_NUM_LOW_BITS;
+                       num_bits = LZMA_LEN_NUM_MID_BITS;
+               } else {
+                       rc_update_bit_1(rc, prob_len);
+                       prob_len = prob + LZMA_LEN_HIGH;
+                       offset = ((1 << LZMA_LEN_NUM_LOW_BITS)
+                                 + (1 << LZMA_LEN_NUM_MID_BITS));
+                       num_bits = LZMA_LEN_NUM_HIGH_BITS;
+               }
+       }
+
+       rc_bit_tree_decode(rc, prob_len, num_bits, &len);
+       len += offset;
+
+       if (cst->state < 4) {
+               int pos_slot;
+
+               cst->state += LZMA_NUM_LIT_STATES;
+               prob =
+                       p + LZMA_POS_SLOT +
+                       ((len <
+                         LZMA_NUM_LEN_TO_POS_STATES ? len :
+                         LZMA_NUM_LEN_TO_POS_STATES - 1)
+                        << LZMA_NUM_POS_SLOT_BITS);
+               rc_bit_tree_decode(rc, prob,
+                                  LZMA_NUM_POS_SLOT_BITS,
+                                  &pos_slot);
+               if (pos_slot >= LZMA_START_POS_MODEL_INDEX) {
+                       int i, mi;
+                       num_bits = (pos_slot >> 1) - 1;
+                       cst->rep0 = 2 | (pos_slot & 1);
+                       if (pos_slot < LZMA_END_POS_MODEL_INDEX) {
+                               cst->rep0 <<= num_bits;
+                               prob = p + LZMA_SPEC_POS +
+                                       cst->rep0 - pos_slot - 1;
+                       } else {
+                               num_bits -= LZMA_NUM_ALIGN_BITS;
+                               while (num_bits--)
+                                       cst->rep0 = (cst->rep0 << 1) |
+                                               rc_direct_bit(rc);
+                               prob = p + LZMA_ALIGN;
+                               cst->rep0 <<= LZMA_NUM_ALIGN_BITS;
+                               num_bits = LZMA_NUM_ALIGN_BITS;
+                       }
+                       i = 1;
+                       mi = 1;
+                       while (num_bits--) {
+                               if (rc_get_bit(rc, prob + mi, &mi))
+                                       cst->rep0 |= i;
+                               i <<= 1;
+                       }
+               } else
+                       cst->rep0 = pos_slot;
+               if (++(cst->rep0) == 0)
+                       return;
+       }
+
+       len += LZMA_MATCH_MIN_LEN;
+
+       copy_bytes(wr, cst->rep0, len);
+}
+
+
+
+STATIC inline int INIT unlzma(unsigned char *buf, unsigned int in_len,
+                             int(*fill)(void*, unsigned int),
+                             int(*flush)(void*, unsigned int),
+                             unsigned char *output,
+                             unsigned int *posp,
+                             void(*error_fn)(const char *x)
+       )
+{
+       struct lzma_header header;
+       int lc, pb, lp;
+       uint32_t pos_state_mask;
+       uint32_t literal_pos_mask;
+       uint16_t *p;
+       int num_probs;
+       struct rc rc;
+       int i, mi;
+       struct writer wr;
+       struct cstate cst;
+       unsigned char *inbuf;
+       int ret = -1;
+
+       set_error_fn(error_fn);
+
+       if (buf)
+               inbuf = buf;
+       else
+               inbuf = malloc(LZMA_IOBUF_SIZE);
+       if (!inbuf) {
+               error("Could not allocate input bufer");
+               goto exit_0;
+       }
+
+       cst.state = 0;
+       cst.rep0 = cst.rep1 = cst.rep2 = cst.rep3 = 1;
+
+       wr.header = &header;
+       wr.flush = flush;
+       wr.global_pos = 0;
+       wr.previous_byte = 0;
+       wr.buffer_pos = 0;
+
+       rc_init(&rc, fill, inbuf, in_len);
+
+       for (i = 0; i < sizeof(header); i++) {
+               if (rc.ptr >= rc.buffer_end)
+                       rc_read(&rc);
+               ((unsigned char *)&header)[i] = *rc.ptr++;
+       }
+
+       if (header.pos >= (9 * 5 * 5))
+               error("bad header");
+
+       mi = 0;
+       lc = header.pos;
+       while (lc >= 9) {
+               mi++;
+               lc -= 9;
+       }
+       pb = 0;
+       lp = mi;
+       while (lp >= 5) {
+               pb++;
+               lp -= 5;
+       }
+       pos_state_mask = (1 << pb) - 1;
+       literal_pos_mask = (1 << lp) - 1;
+
+       ENDIAN_CONVERT(header.dict_size);
+       ENDIAN_CONVERT(header.dst_size);
+
+       if (header.dict_size == 0)
+               header.dict_size = 1;
+
+       if (output)
+               wr.buffer = output;
+       else {
+               wr.bufsize = MIN(header.dst_size, header.dict_size);
+               wr.buffer = large_malloc(wr.bufsize);
+       }
+       if (wr.buffer == NULL)
+               goto exit_1;
+
+       num_probs = LZMA_BASE_SIZE + (LZMA_LIT_SIZE << (lc + lp));
+       p = (uint16_t *) large_malloc(num_probs * sizeof(*p));
+       if (p == 0)
+               goto exit_2;
+       num_probs = LZMA_LITERAL + (LZMA_LIT_SIZE << (lc + lp));
+       for (i = 0; i < num_probs; i++)
+               p[i] = (1 << RC_MODEL_TOTAL_BITS) >> 1;
+
+       rc_init_code(&rc);
+
+       while (get_pos(&wr) < header.dst_size) {
+               int pos_state = get_pos(&wr) & pos_state_mask;
+               uint16_t *prob = p + LZMA_IS_MATCH +
+                       (cst.state << LZMA_NUM_POS_BITS_MAX) + pos_state;
+               if (rc_is_bit_0(&rc, prob))
+                       process_bit0(&wr, &rc, &cst, p, pos_state, prob,
+                                    lc, literal_pos_mask);
+               else {
+                       process_bit1(&wr, &rc, &cst, p, pos_state, prob);
+                       if (cst.rep0 == 0)
+                               break;
+               }
+       }
+
+       if (posp)
+               *posp = rc.ptr-rc.buffer;
+       if (wr.flush)
+               wr.flush(wr.buffer, wr.buffer_pos);
+       ret = 0;
+       large_free(p);
+exit_2:
+       if (!output)
+               large_free(wr.buffer);
+exit_1:
+       if (!buf)
+               free(inbuf);
+exit_0:
+       return ret;
+}
diff -r ac9d4ba48b83 -r c4630f8f69cc xen/include/xen/decompress.h
--- /dev/null   Thu Jan 01 00:00:00 1970 +0000
+++ b/xen/include/xen/decompress.h      Mon Nov 09 07:52:27 2009 +0000
@@ -0,0 +1,38 @@
+#ifndef __XEN_GENERIC_H
+#define __XEN_GENERIC_H
+
+typedef int decompress_fn(unsigned char *inbuf, unsigned int len,
+                          int (*fill)(void*, unsigned int),
+                          int (*flush)(void*, unsigned int),
+                          unsigned char *outbuf, unsigned int *posp,
+                          void (*error)(const char *x));
+
+/* inbuf   - input buffer
+ * len     - len of pre-read data in inbuf
+ * fill    - function to fill inbuf when empty
+ * flush   - function to write out outbuf
+ * outbuf  - output buffer
+ * posp    - if non-null, input position (number of bytes read) will be
+ *           returned here
+ * error   - error reporting function
+ *
+ * If len != 0, inbuf should contain all the necessary input data, and fill
+ * should be NULL
+ * If len = 0, inbuf can be NULL, in which case the decompressor will allocate
+ * the input buffer.  If inbuf != NULL it must be at least XXX_IOBUF_SIZE 
bytes.
+ * fill will be called (repeatedly...) to read data, at most XXX_IOBUF_SIZE
+ * bytes should be read per call.  Replace XXX with the appropriate 
decompressor
+ * name, i.e. LZMA_IOBUF_SIZE.
+ *
+ * If flush = NULL, outbuf must be large enough to buffer all the expected
+ * output.  If flush != NULL, the output buffer will be allocated by the
+ * decompressor (outbuf = NULL), and the flush function will be called to
+ * flush the output buffer at the appropriate time (decompressor and stream
+ * dependent).
+ */
+
+decompress_fn bunzip2, unlzma;
+
+int decompress(void *inbuf, unsigned int len, void *outbuf);
+
+#endif

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