/* inflate.c -- Not copyrighted 1992 by Mark Adler   version c10p1, 10 January 1993 *//* You can do whatever you like with this source file, though I would   prefer that if you modify it and redistribute it that you include   comments to that effect with your name and the date.  Thank you.   [The history has been moved to the file ChangeLog.] *//*   Inflate deflated (PKZIP's method 8 compressed) data.  The compression   method searches for as much of the current string of bytes (up to a   length of 258) in the previous 32K bytes.  If it doesn't find any   matches (of at least length 3), it codes the next byte.  Otherwise, it   codes the length of the matched string and its distance backwards from   the current position.  There is a single Huffman code that codes both   single bytes (called "literals") and match lengths.  A second Huffman   code codes the distance information, which follows a length code.  Each   length or distance code actually represents a base value and a number   of "extra" (sometimes zero) bits to get to add to the base value.  At   the end of each deflated block is a special end-of-block (EOB) literal/   length code.  The decoding process is basically: get a literal/length   code; if EOB then done; if a literal, emit the decoded byte; if a   length then get the distance and emit the referred-to bytes from the   sliding window of previously emitted data.   There are (currently) three kinds of inflate blocks: stored, fixed, and   dynamic.  The compressor deals with some chunk of data at a time, and   decides which method to use on a chunk-by-chunk basis.  A chunk might   typically be 32K or 64K.  If the chunk is uncompressible, then the   "stored" method is used.  In this case, the bytes are simply stored as   is, eight bits per byte, with none of the above coding.  The bytes are   preceded by a count, since there is no longer an EOB code.   If the data is compressible, then either the fixed or dynamic methods   are used.  In the dynamic method, the compressed data is preceded by   an encoding of the literal/length and distance Huffman codes that are   to be used to decode this block.  The representation is itself Huffman   coded, and so is preceded by a description of that code.  These code   descriptions take up a little space, and so for small blocks, there is   a predefined set of codes, called the fixed codes.  The fixed method is   used if the block codes up smaller that way (usually for quite small   chunks), otherwise the dynamic method is used.  In the latter case, the   codes are customized to the probabilities in the current block, and so   can code it much better than the pre-determined fixed codes.    The Huffman codes themselves are decoded using a mutli-level table   lookup, in order to maximize the speed of decoding plus the speed of   building the decoding tables.  See the comments below that precede the   lbits and dbits tuning parameters. *//*   Notes beyond the 1.93a appnote.txt:   1. Distance pointers never point before the beginning of the output      stream.   2. Distance pointers can point back across blocks, up to 32k away.   3. There is an implied maximum of 7 bits for the bit length table and      15 bits for the actual data.   4. If only one code exists, then it is encoded using one bit.  (Zero      would be more efficient, but perhaps a little confusing.)  If two      codes exist, they are coded using one bit each (0 and 1).   5. There is no way of sending zero distance codes--a dummy must be      sent if there are none.  (History: a pre 2.0 version of PKZIP would      store blocks with no distance codes, but this was discovered to be      too harsh a criterion.)  Valid only for 1.93a.  2.04c does allow      zero distance codes, which is sent as one code of zero bits in      length.   6. There are up to 286 literal/length codes.  Code 256 represents the      end-of-block.  Note however that the static length tree defines      288 codes just to fill out the Huffman codes.  Codes 286 and 287      cannot be used though, since there is no length base or extra bits      defined for them.  Similarly, there are up to 30 distance codes.      However, static trees define 32 codes (all 5 bits) to fill out the      Huffman codes, but the last two had better not show up in the data.   7. Unzip can check dynamic Huffman blocks for complete code sets.      The exception is that a single code would not be complete (see #4).   8. The five bits following the block type is really the number of      literal codes sent minus 257.   9. Length codes 8,16,16 are interpreted as 13 length codes of 8 bits      (1+6+6).  Therefore, to output three times the length, you output      three codes (1+1+1), whereas to output four times the same length,      you only need two codes (1+3).  Hmm.  10. In the tree reconstruction algorithm, Code = Code + Increment      only if BitLength(i) is not zero.  (Pretty obvious.)  11. Correction: 4 Bits: # of Bit Length codes - 4     (4 - 19)  12. Note: length code 284 can represent 227-258, but length code 285      really is 258.  The last length deserves its own, short code      since it gets used a lot in very redundant files.  The length      258 is special since 258 - 3 (the min match length) is 255.  13. The literal/length and distance code bit lengths are read as a      single stream of lengths.  It is possible (and advantageous) for      a repeat code (16, 17, or 18) to go across the boundary between      the two sets of lengths. */#ifdef RCSIDstatic char rcsid[] = "$Id: inflate.c,v 0.14 1993/06/10 13:27:04 jloup Exp $";#endif#include <sys/types.h>#include "tailor.h"#if defined(STDC_HEADERS) || !defined(NO_STDLIB_H)#  include <stdlib.h>#endif#include "gzip.h"#include "bsdebug.h"//#define _DEBUG_INFLATE_C_#ifdef DBGPrintfi#undef DBGPrintfi#endif#ifdef DBGPrintfo#undef DBGPrintfo#endif#if defined(_TRACEHELPER_DEBUG_ALL_)  #define DBGPrintfi(a) DbgPrintfi a;  #define DBGPrintfo(a) DbgPrintfo a;#elif defined(_DEBUG_INFLATE_C_) && defined(_TRACEHELPER_DEBUG_EACH_OF_FILE_)  #define DBGPrintfi(a) DbgPrintfi a;  #define DBGPrintfo(a) DbgPrintfo a;#else  #define DBGPrintfi(a)  #define DBGPrintfo(a)#endif#define slide window/* Huffman code lookup table entry--this entry is four bytes for machines   that have 16-bit pointers (e.g. PC's in the small or medium model).   Valid extra bits are 0..13.  e == 15 is EOB (end of block), e == 16   means that v is a literal, 16 < e < 32 means that v is a pointer to   the next table, which codes e - 16 bits, and lastly e == 99 indicates   an unused code.  If a code with e == 99 is looked up, this implies an   error in the data. */struct huft {  uch e;                /* number of extra bits or operation */  uch b;                /* number of bits in this code or subcode */  union {    ush n;              /* literal, length base, or distance base */    struct huft *t;     /* pointer to next level of table */  } v;};/* Function prototypes */int huft_build OF((unsigned *, unsigned, unsigned, ush *, unsigned, ush *, unsigned, struct huft **, int *));int huft_free OF((struct huft *));int inflate_codes OF((struct huft *, struct huft *, int, int));int inflate_stored OF((void));int inflate_fixed OF((void));int inflate_dynamic OF((void));int inflate_block OF((int *));int gzip_inflate OF((void));/* The inflate algorithm uses a sliding 32K byte window on the uncompressed   stream to find repeated byte strings.  This is implemented here as a   circular buffer.  The index is updated simply by incrementing and then   and'ing with 0x7fff (32K-1). *//* It is left to other modules to supply the 32K area.  It is assumed   to be usable as if it were declared "uch slide[32768];" or as just   "uch *slide;" and then malloc'ed in the latter case.  The definition   must be in unzip.h, included above. *//* unsigned wp;             current position in slide */#define wp outcnt#define flush_output(w) (wp=(w),flush_window())/* Tables for deflate from PKZIP's appnote.txt. */static unsigned border[] = {    /* Order of the bit length code lengths */        16, 17, 18, 0, 8, 7, 9, 6, 10, 5, 11, 4, 12, 3, 13, 2, 14, 1, 15};static ush cplens[] = {         /* Copy lengths for literal codes 257..285 */        3, 4, 5, 6, 7, 8, 9, 10, 11, 13, 15, 17, 19, 23, 27, 31,        35, 43, 51, 59, 67, 83, 99, 115, 131, 163, 195, 227, 258, 0, 0};        /* note: see note #13 above about the 258 in this list. */static ush cplext[] = {         /* Extra bits for literal codes 257..285 */        0, 0, 0, 0, 0, 0, 0, 0, 1, 1, 1, 1, 2, 2, 2, 2,        3, 3, 3, 3, 4, 4, 4, 4, 5, 5, 5, 5, 0, 99, 99}; /* 99==invalid */static ush cpdist[] = {         /* Copy offsets for distance codes 0..29 */        1, 2, 3, 4, 5, 7, 9, 13, 17, 25, 33, 49, 65, 97, 129, 193,        257, 385, 513, 769, 1025, 1537, 2049, 3073, 4097, 6145,        8193, 12289, 16385, 24577};static ush cpdext[] = {         /* Extra bits for distance codes */        0, 0, 0, 0, 1, 1, 2, 2, 3, 3, 4, 4, 5, 5, 6, 6,        7, 7, 8, 8, 9, 9, 10, 10, 11, 11,        12, 12, 13, 13};/* Macros for inflate() bit peeking and grabbing.   The usage is:           NEEDBITS(j)        x = b & mask_bits[j];        DUMPBITS(j)   where NEEDBITS makes sure that b has at least j bits in it, and   DUMPBITS removes the bits from b.  The macros use the variable k   for the number of bits in b.  Normally, b and k are register   variables for speed, and are initialized at the beginning of a   routine that uses these macros from a global bit buffer and count.   If we assume that EOB will be the longest code, then we will never   ask for bits with NEEDBITS that are beyond the end of the stream.   So, NEEDBITS should not read any more bytes than are needed to   meet the request.  Then no bytes need to be "returned" to the buffer   at the end of the last block.   However, this assumption is not true for fixed blocks--the EOB code   is 7 bits, but the other literal/length codes can be 8 or 9 bits.   (The EOB code is shorter than other codes because fixed blocks are   generally short.  So, while a block always has an EOB, many other   literal/length codes have a significantly lower probability of   showing up at all.)  However, by making the first table have a   lookup of seven bits, the EOB code will be found in that first   lookup, and so will not require that too many bits be pulled from   the stream. */ulg bb;                         /* bit buffer */unsigned bk;                    /* bits in bit buffer */ush mask_bits[] = {    0x0000,    0x0001, 0x0003, 0x0007, 0x000f, 0x001f, 0x003f, 0x007f, 0x00ff,    0x01ff, 0x03ff, 0x07ff, 0x0fff, 0x1fff, 0x3fff, 0x7fff, 0xffff};#ifdef CRYPT  uch cc;#  define NEXTBYTE() \     (decrypt ? (cc = get_byte(), zdecode(cc), cc) : get_byte())#else#  define NEXTBYTE()  (uch)get_byte()#endif#define NEEDBITS(n) {while(k<(n)){b|=((ulg)NEXTBYTE())<<k;k+=8;}}#define DUMPBITS(n) {b>>=(n);k-=(n);}/*   Huffman code decoding is performed using a multi-level table lookup.   The fastest way to decode is to simply build a lookup table whose   size is determined by the longest code.  However, the time it takes   to build this table can also be a factor if the data being decoded   is not very long.  The most common codes are necessarily the   shortest codes, so those codes dominate the decoding time, and hence   the speed.  The idea is you can have a shorter table that decodes the   shorter, more probable codes, and then point to subsidiary tables for   the longer codes.  The time it costs to decode the longer codes is   then traded against the time it takes to make longer tables.   This results of this trade are in the variables lbits and dbits   below.  lbits is the number of bits the first level table for literal/   length codes can decode in one step, and dbits is the same thing for   the distance codes.  Subsequent tables are also less than or equal to   those sizes.  These values may be adjusted either when all of the   codes are shorter than that, in which case the longest code length in   bits is used, or when the shortest code is *longer* than the requested   table size, in which case the length of the shortest code in bits is   used.   There are two different values for the two tables, since they code a   different number of possibilities each.  The literal/length table   codes 286 possible values, or in a flat code, a little over eight   bits.  The distance table codes 30 possible values, or a little less   than five bits, flat.  The optimum values for speed end up being   about one bit more than those, so lbits is 8+1 and dbits is 5+1.   The optimum values may differ though from machine to machine, and   possibly even between compilers.  Your mileage may vary. */int lbits = 9;          /* bits in base literal/length lookup table */int dbits = 6;          /* bits in base distance lookup table *//* If BMAX needs to be larger than 16, then h and x[] should be ulg. */#define BMAX 16         /* maximum bit length of any code (16 for explode) */#define N_MAX 288       /* maximum number of codes in any set */unsigned hufts;         /* track memory usage */extern char *TPEG_malloc(int size);	int huft_build(b, n, s, d,ds, e,es, t, m)unsigned *b;            /* code lengths in bits (all assumed <= BMAX) */unsigned n;             /* number of codes (assumed <= N_MAX) */unsigned s;             /* number of simple-valued codes (0..s-1) */ush *d;                 /* list of base values for non-simple codes */unsigned ds;		/*d[ds] : max ds*/ush *e;                 /* list of extra bits for non-simple codes */unsigned es;		/*d[es] : max es*/struct huft **t;        /* result: starting table */int *m;                 /* maximum lookup bits, returns actual *//* Given a list of code lengths and a maximum table size, make a set of   tables to decode that set of codes.  Return zero on success, one if   the given code set is incomplete (the tables are still built in this   case), two if the input is invalid (all zero length codes or an   oversubscribed set of lengths), and three if not enough memory. */{  DBGPrintfi(("huft_build(In)\r\n"));  {  unsigned a;                   /* counter for codes of length k */  unsigned c[BMAX+1];           /* bit length count table */  unsigned f;                   /* i repeats in table every f entries */  int g;                        /* maximum code length */  int h;                        /* table level */  register unsigned i;          /* counter, current code */  register unsigned j;          /* counter */  register int k;               /* number of bits in current code */  int l;                        /* bits per table (returned in m) */  register unsigned *p;         /* pointer into c[], b[], or v[] */  register struct huft *q;      /* points to current table */  struct huft r;                /* table entry for structure assignment */  struct huft *u[BMAX];         /* table stack */  unsigned v[N_MAX];            /* values in order of bit length */  register int w;               /* bits before this table == (l * h) */  unsigned x[BMAX+1];           /* bit offsets, then code stack */  unsigned *xp;                 /* pointer into x */  int y;                        /* number of dummy codes added */  unsigned z;                   /* number of entries in current table */  /* Generate counts for each bit length */  memzero(c, sizeof(c));  p = b;  i = n;  do {    Tracecv(*p, (stderr, (n-i >= ' ' && n-i <= '~' ? "%c %d\n" : "0x%x %d\n"), 	    n-i, *p));    c[*p]++;                    /* assume all entries <= BMAX */    p++;                      /* Can't combine with above line (Solaris bug) */  } while (--i);  if (c[0] == n)                /* null input--all zero length codes */  {    *t = (struct huft *)NULL;    *m = 0;        DBGPrintfo(("huft_build(out1)\r\n"));    return  0;  }  /* Find minimum and maximum length, bound *m by those */  l = *m;  for (j = 1; j <= BMAX; j++)    if (c[j])      break;  k = j;                        /* minimum code length */  if ((unsigned)l < j)    l = j;  for (i = BMAX; i; i--)    if (c[i])      break;  g = i;                        /* maximum code length */  if ((unsigned)l > i)    l = i;  *m = l;  /* Adjust last length count to fill out codes, if needed */  for (y = 1 << j; j < i; j++, y <<= 1)    if ((y -= c[j]) < 0)    {      DBGPrintfo(("huft_build(out11)\r\n"));      return 2;                 /* bad input: more codes than bits */