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/* 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>
#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 =
|