+++ /dev/null
-/* vi: set sw=4 ts=4: */
-/* 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
- */
-
-/* May 21, 2004 Manuel Novoa III
- * Modified to load a bzip'd kernel on the linksys wrt54g.
- *
- * May 30, 2004
- * Further size reduction via inlining and disabling len check code.
- */
-
-/**********************************************************************/
-
-/* Note... the LED code is specific to the v2.0 (and GS?) unit. */
-#undef ENABLE_LEDS
-/* #define ENABLE_LEDS 1 */
-
-/* Do we want to bother with checking the bzip'd data for errors? */
-#undef ENABLE_BUNZIP_CHECKING
-/* #define ENABLE_BUNZIP_CHECKING 1 */
-
-/**********************************************************************/
-/* #include <bcm4710.h> */
-#define BCM4710_FLASH 0x1fc00000 /* Flash */
-
-#define KSEG0 0x80000000
-#define KSEG1 0xa0000000
-
-#define KSEG1ADDR(a) ((((unsigned)(a)) & 0x1fffffffU) | KSEG1)
-
-/* The following cache code was taken from the file bcm4710_cache.h
- * which was necessarily GPL as it was used to build the linksys
- * kernel for the wrt54g. */
-
-#warning icache [l]size hardcoded
-
-#define icache_size 8192
-#define ic_lsize 16
-
-#define Index_Invalidate_I 0x00
-
-#define cache_unroll(base,op) \
- __asm__ __volatile__( \
- ".set noreorder;\n" \
- ".set mips3;\n" \
- "cache %1, (%0);\n" \
- ".set mips0;\n" \
- ".set reorder\n" \
- : \
- : "r" (base), \
- "i" (op));
-
-static __inline__ void blast_icache(void)
-{
- unsigned long start = KSEG0;
- unsigned long end = (start + icache_size);
-
- while(start < end) {
- cache_unroll(start,Index_Invalidate_I);
- start += ic_lsize;
- }
-}
-
-/**********************************************************************/
-#ifndef INT_MAX
-#define INT_MAX (((1 << 30)-1)*2 + 1)
-#endif
-/**********************************************************************/
-#ifdef ENABLE_BUNZIP_CHECKING
-
-#define REBOOT do {} while (1)
-
-#else
-
-#define REBOOT ((void) 0)
-
-#endif
-/**********************************************************************/
-#ifdef ENABLE_LEDS
-
-#define LED_POWER_ON 0x02 /* OFF == flashing */
-#define LED_DMZ_OFF 0x80
-#define LED_WLAN_OFF 0x01
-
-#define LED_CODE_0 (LED_POWER_ON | LED_DMZ_OFF | LED_WLAN_OFF)
-#define LED_CODE_1 (LED_POWER_ON | LED_DMZ_OFF)
-#define LED_CODE_2 (LED_POWER_ON | LED_WLAN_OFF)
-#define LED_CODE_3 (LED_POWER_ON)
-
-#define SET_LED_ERROR(X) \
- do { \
- *(volatile u8*)(KSEG1ADDR(0x18000064))=(X & ~LED_POWER_ON); \
- *(volatile u8*)(KSEG1ADDR(0x18000068))=0; /* Disable changes */ \
- REBOOT; \
- } while (0)
-
-#define SET_LED(X) *(volatile u8*)(KSEG1ADDR(0x18000064))=X;
-
-
-typedef unsigned char u8;
-
-#else
-
-#define SET_LED_ERROR(X) REBOOT
-#define SET_LED(X) ((void)0)
-
-#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 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],base[MAX_HUFCODE_BITS],permute[MAX_SYMBOLS];
- int minLen, maxLen;
-};
-
-/* Structure holding all the housekeeping data, including IO buffers and
- memory that persists between calls to bunzip */
-typedef struct {
- /* State for interrupting output loop */
- int writeCopies,writePos,writeRunCountdown,writeCount,writeCurrent;
- /* I/O tracking data (file handles, buffers, positions, etc.) */
-#if defined(ENABLE_BUNZIP_CHECKING)
- int /*in_fd,out_fd,*/ inbufCount,inbufPos /*,outbufPos*/;
-#else
- int /*in_fd,out_fd,inbufCount,*/ inbufPos /*,outbufPos*/;
-#endif
- unsigned char *inbuf /*,*outbuf*/;
- unsigned int inbufBitCount, inbufBits;
- /* The CRC values stored in the block header and calculated from the data */
-#ifdef ENABLE_BUNZIP_CHECKING
- unsigned int crc32Table[256],headerCRC, totalCRC, writeCRC;
- /* Intermediate buffer and its size (in bytes) */
- unsigned int *dbuf, dbufSize;
-#else
- unsigned int *dbuf;
-#endif
- /* 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 */
-} bunzip_data;
-
-static int get_next_block(bunzip_data *bd);
-
-/**********************************************************************/
-/* 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 __inline__ int read_bunzip(bunzip_data *bd, char *outbuf, int len)
-{
- const unsigned int *dbuf;
- int pos,current,previous,gotcount;
-#ifdef ENABLE_LEDS
- int led_state = LED_CODE_2;
-#endif
-
- /* 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;
- current=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 0 /* Might want to enable this if passing a limiting size. */
-/* #ifdef ENABLE_BUNZIP_CHECKING */
- /* If the output buffer is full, snapshot state and return */
- if(gotcount >= len) {
- bd->writePos=pos;
- bd->writeCurrent=current;
- bd->writeCopies++;
- return len;
- }
-#endif
- /* Write next byte into output buffer, updating CRC */
- outbuf[gotcount++] = current;
-#ifdef ENABLE_BUNZIP_CHECKING
- bd->writeCRC=(((bd->writeCRC)<<8)
- ^bd->crc32Table[((bd->writeCRC)>>24)^current]);
-#endif
- /* 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=current;
- pos=dbuf[pos];
- current=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(current!=previous) bd->writeRunCountdown=4;
- } else {
- /* We have a repeated run, this byte indicates the count */
- bd->writeCopies=current;
- current=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;
- }
- }
-#ifdef ENABLE_BUNZIP_CHECKING
- /* 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;
- }
-#endif
- }
-
-#ifdef ENABLE_LEDS
- if (led_state == LED_CODE_2) {
- led_state = LED_CODE_1;
- } else {
- led_state = LED_CODE_2;
- }
- SET_LED(led_state);
-#endif
-
- /* 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);
-#ifdef ENABLE_BUNZIP_CHECKING
- if(previous) {
- bd->writeCount=previous;
- return (previous!=RETVAL_LAST_BLOCK) ? previous : gotcount;
- }
- bd->writeCRC=0xffffffffUL;
-#else
- if (previous) return gotcount;
-#endif
- pos=bd->writePos;
- current=bd->writeCurrent;
- goto decode_next_byte;
-}
-
-/**********************************************************************/
-/* WARNING!!! Must be the first function!!! */
-
-void load_and_run(unsigned long ra)
-{
- int dbuf[900000]; /* Maximum requred */
- bunzip_data bd;
-
- unsigned int i;
-#ifdef ENABLE_BUNZIP_CHECKING
- unsigned int j, c;
- int r;
-#endif
- char *p;
-
-#ifdef ENABLE_LEDS
- *(volatile u8*)(KSEG1ADDR(0x18000068))=0x83; /* Allow all bits to change */
- SET_LED(LED_CODE_0);
-#endif
-
-/* memset(&bd,0,sizeof(bunzip_data)); */
- p = (char *) &bd;
- for (i = 0 ; i < sizeof(bunzip_data) ; i++) {
- p[i] = 0;
- }
-
- /* Find start of flash and adjust for pmon partition. */
- p = ((char *) KSEG1ADDR(BCM4710_FLASH)) + 0x10000;
-
- SET_LED(LED_CODE_1);
- /* Find the start of the bzip'd data. */
- while ((p[0]!='B') || (p[1]!='Z') || (p[2]!='h') /*|| (p[3]!='9')*/) ++p;
- SET_LED(LED_CODE_2);
-
- /* Setup input buffer */
- bd.inbuf=p+4; /* Skip the "BZh9" header. */
-#ifdef ENABLE_BUNZIP_CHECKING
- bd.inbufCount=INT_MAX;
- /* 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;
- }
-
- bd.dbufSize=900000;
-#endif
- bd.dbuf=dbuf;
-
- /* Actually do the bunzip */
-#ifdef ENABLE_BUNZIP_CHECKING
- r = read_bunzip(&bd, ((char *) LOADADDR), INT_MAX);
- if (r > 0) {
- if (bd.headerCRC==bd.totalCRC) {
- SET_LED(LED_CODE_3);
- {
- int code = LED_WLAN_OFF;
- int i, j;
- for (j=0 ; j < 4 ; j++) {
- for (i=0; i<(1<<27) ; i++) {}
- SET_LED(code);
- code ^= LED_WLAN_OFF;
- }
- }
- blast_icache();
- /* Jump to load address */
- ((void (*)(void)) LOADADDR)();
- } else {
- SET_LED_ERROR(LED_CODE_3);
- }
- } else {
- SET_LED_ERROR(LED_CODE_2);
- }
-#else
- read_bunzip(&bd, ((char *) LOADADDR), INT_MAX);
- blast_icache();
- /* Jump to load address */
- ((void (*)(void)) LOADADDR)();
-#endif
-}
-
-/**********************************************************************/
-/* 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 get_bits(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 */
-#ifdef ENABLE_BUNZIP_CHECKING
- if(bd->inbufPos==bd->inbufCount) {
- SET_LED_ERROR(LED_CODE_0);
- }
-#endif
- /* 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 get_next_block(bunzip_data *bd)
-{
- struct group_data *hufGroup;
-#ifdef ENABLE_BUNZIP_CHECKING
- int dbufCount,nextSym,dbufSize,groupCount,*base,*limit,selector,
- i,j,k,t,runPos,symCount,symTotal,nSelectors,byteCount[256];
-#else
- int dbufCount,nextSym,/*dbufSize,*/groupCount,*base,*limit,selector,
- i,j,k,t,runPos,symCount,symTotal,nSelectors,byteCount[256];
-#endif
- unsigned char uc, symToByte[256], mtfSymbol[256], *selectors;
- unsigned int *dbuf,origPtr;
-
- dbuf=bd->dbuf;
-#ifdef ENABLE_BUNZIP_CHECKING
- dbufSize=bd->dbufSize;
-#endif
- 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);
-#ifdef ENABLE_BUNZIP_CHECKING
- 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;
- if((origPtr=get_bits(bd,24)) > dbufSize) return RETVAL_DATA_ERROR;
-#else
- get_bits(bd,32);
- if ((i == 0x177245) && (j == 0x385090)) return RETVAL_LAST_BLOCK;
- get_bits(bd,1);
- origPtr=get_bits(bd,24);
-#endif
- /* 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);
-#ifdef ENABLE_BUNZIP_CHECKING
- if (groupCount<2 || groupCount>MAX_GROUPS) return RETVAL_DATA_ERROR;
-#endif
- /* 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.) */
-#ifdef ENABLE_BUNZIP_CHECKING
- if(!(nSelectors=get_bits(bd, 15))) return RETVAL_DATA_ERROR;
-#else
- nSelectors=get_bits(bd, 15);
-#endif
- for(i=0; i<groupCount; i++) mtfSymbol[i] = i;
- for(i=0; i<nSelectors; i++) {
- /* Get next value */
-#ifdef ENABLE_BUNZIP_CHECKING
- for(j=0;get_bits(bd,1);j++) if (j>=groupCount) return RETVAL_DATA_ERROR;
-#else
- for(j=0;get_bits(bd,1);j++) ;
-#endif
- /* 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(;;) {
-#ifdef ENABLE_BUNZIP_CHECKING
- if (((unsigned)t) > (MAX_HUFCODE_BITS-1))
- return RETVAL_DATA_ERROR;
-#endif
- /* 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;
-#ifdef ENABLE_BUNZIP_CHECKING
- if(selector>=nSelectors) return RETVAL_DATA_ERROR;
-#endif
- 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) {
-#ifdef ENABLE_BUNZIP_CHECKING
- if(bd->inbufPos==bd->inbufCount) {
- j = get_bits(bd,hufGroup->maxLen);
- goto got_huff_bits;
- }
-#endif
- 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) */
-#ifdef ENABLE_BUNZIP_CHECKING
- if ((i > hufGroup->maxLen)
- || (((unsigned)(j=(j>>(hufGroup->maxLen-i))-base[i]))
- >= MAX_SYMBOLS))
- return RETVAL_DATA_ERROR;
-#else
- j=(j>>(hufGroup->maxLen-i))-base[i];
-#endif
- 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;
-#ifdef ENABLE_BUNZIP_CHECKING
- if(dbufCount+t>=dbufSize) return RETVAL_DATA_ERROR;
-#endif
-
- 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.) */
-#ifdef ENABLE_BUNZIP_CHECKING
- if(dbufCount>=dbufSize) return RETVAL_DATA_ERROR;
-#endif
- 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) {
-#ifdef ENABLE_BUNZIP_CHECKING
- if(origPtr>=dbufCount) return RETVAL_DATA_ERROR;
-#endif
- bd->writePos=dbuf[origPtr];
- bd->writeCurrent=(unsigned char)(bd->writePos&0xff);
- bd->writePos>>=8;
- bd->writeRunCountdown=5;
- }
- bd->writeCount=dbufCount;
-
- return RETVAL_OK;
-}
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