Adding upstream version 4.19.249.upstream/4.19.249upstream

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 756 insertions, 0 deletions

diff --git a/lib/decompress_bunzip2.c b/lib/decompress_bunzip2.c
new file mode 100644
index 000000000..7c4932eed
--- /dev/null
+++ b/lib/decompress_bunzip2.c
@@ -0,0 +1,756 @@
+/*	Small bzip2 deflate implementation, by Rob Landley (rob@landley.net).
+
+	Based on bzip2 decompression code by Julian R Seward (jseward@acm.org),
+	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@codepoet.org).
+
+	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@knaff.lu)
+*/
+
+
+#ifdef STATIC
+#define PREBOOT
+#else
+#include <linux/decompress/bunzip2.h>
+#endif /* STATIC */
+
+#include <linux/decompress/mm.h>
+#include <linux/crc32poly.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.) */
+	long (*fill)(void*, unsigned long);
+	long 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 */
+	int byteCount[256];
+	unsigned char symToByte[256], mtfSymbol[256];
+};
+
+
+/* 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;
+	unsigned char uc, *symToByte, *mtfSymbol, *selectors;
+	unsigned int *dbuf, origPtr;
+
+	dbuf = bd->dbuf;
+	dbufSize = bd->dbufSize;
+	selectors = bd->selectors;
+	byteCount = bd->byteCount;
+	symToByte = bd->symToByte;
+	mtfSymbol = bd->mtfSymbol;
+
+	/* 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[].  Concurrently, 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, 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 long INIT nofill(void *buf, unsigned long 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, long len,
+			     long (*fill)(void*, unsigned long))
+{
+	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);
+	if (!bd)
+		return RETVAL_OUT_OF_MEMORY;
+	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)^(CRC32_POLY_BE) : (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));
+	if (!bd->dbuf)
+		return RETVAL_OUT_OF_MEMORY;
+	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, long len,
+			long (*fill)(void*, unsigned long),
+			long (*flush)(void*, unsigned long),
+			unsigned char *outbuf,
+			long *pos,
+			void(*error)(char *x))
+{
+	struct bunzip_data *bd;
+	int i = -1;
+	unsigned char *inbuf;
+
+	if (flush)
+		outbuf = malloc(BZIP2_IOBUF_SIZE);
+
+	if (!outbuf) {
+		error("Could not allocate output buffer");
+		return RETVAL_OUT_OF_MEMORY;
+	}
+	if (buf)
+		inbuf = buf;
+	else
+		inbuf = malloc(BZIP2_IOBUF_SIZE);
+	if (!inbuf) {
+		error("Could not allocate input buffer");
+		i = RETVAL_OUT_OF_MEMORY;
+		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)
+		goto exit_1;
+	if (bd->dbuf)
+		large_free(bd->dbuf);
+	if (pos)
+		*pos = bd->inbufPos;
+	free(bd);
+exit_1:
+	if (!buf)
+		free(inbuf);
+exit_0:
+	if (flush)
+		free(outbuf);
+	return i;
+}
+
+#ifdef PREBOOT
+STATIC int INIT __decompress(unsigned char *buf, long len,
+			long (*fill)(void*, unsigned long),
+			long (*flush)(void*, unsigned long),
+			unsigned char *outbuf, long olen,
+			long *pos,
+			void (*error)(char *x))
+{
+	return bunzip2(buf, len - 4, fill, flush, outbuf, pos, error);
+}
+#endif