diff options
Diffstat (limited to 'package/linux/kernel-source/arch/mips/brcm-boards/bcm947xx/compressed/decompress_bunzip2.c')
| -rw-r--r-- | package/linux/kernel-source/arch/mips/brcm-boards/bcm947xx/compressed/decompress_bunzip2.c | 758 |
1 files changed, 758 insertions, 0 deletions
diff --git a/package/linux/kernel-source/arch/mips/brcm-boards/bcm947xx/compressed/decompress_bunzip2.c b/package/linux/kernel-source/arch/mips/brcm-boards/bcm947xx/compressed/decompress_bunzip2.c new file mode 100644 index 0000000000..9a120796ff --- /dev/null +++ b/package/linux/kernel-source/arch/mips/brcm-boards/bcm947xx/compressed/decompress_bunzip2.c @@ -0,0 +1,758 @@ +/* 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; +} |