utils/Install/sfxzip/explode.c

   1 /* explode.c -- put in the public domain by Mark Adler
   2    version c15, 6 July 1996 */
   3
   4
   5 /* You can do whatever you like with this source file, though I would
   6    prefer that if you modify it and redistribute it that you include
   7    comments to that effect with your name and the date.  Thank you.
   8
   9    History:
  10    vers    date          who           what
  11    ----  ---------  --------------  ------------------------------------
  12     c1   30 Mar 92  M. Adler        explode that uses huft_build from inflate
  13                                     (this gives over a 70% speed improvement
  14                                     over the original unimplode.c, which
  15                                     decoded a bit at a time)
  16     c2    4 Apr 92  M. Adler        fixed bug for file sizes a multiple of 32k.
  17     c3   10 Apr 92  M. Adler        added a little memory tracking if DEBUG
  18     c4   11 Apr 92  M. Adler        added NOMEMCPY do kill use of memcpy()
  19     c5   21 Apr 92  M. Adler        added the WSIZE #define to allow reducing
  20                                     the 32K window size for specialized
  21                                     applications.
  22     c6   31 May 92  M. Adler        added typecasts to eliminate some warnings
  23     c7   27 Jun 92  G. Roelofs      added more typecasts.
  24     c8   17 Oct 92  G. Roelofs      changed ULONG/UWORD/byte to ulg/ush/uch.
  25     c9   19 Jul 93  J. Bush         added more typecasts (to return values);
  26                                     made l[256] array static for Amiga.
  27     c10   8 Oct 93  G. Roelofs      added used_csize for diagnostics; added
  28                                     buf and unshrink arguments to flush();
  29                                     undef'd various macros at end for Turbo C;
  30                                     removed NEXTBYTE macro (now in unzip.h)
  31                                     and bytebuf variable (not used); changed
  32                                     memset() to memzero().
  33     c11   9 Jan 94  M. Adler        fixed incorrect used_csize calculation.
  34     c12   9 Apr 94  G. Roelofs      fixed split comments on preprocessor lines
  35                                     to avoid bug in Encore compiler.
  36     c13  25 Aug 94  M. Adler        fixed distance-length comment (orig c9 fix)
  37     c14  22 Nov 95  S. Maxwell      removed unnecessary "static" on auto array
  38     c15   6 Jul 96  W. Haidinger    added ulg typecasts to flush() calls.
  39     c16   8 Feb 98  C. Spieler      added ZCONST modifiers to const tables
  40                                     and #ifdef DEBUG around debugging code.
  41     c16b 25 Mar 98  C. Spieler      modified DLL code for slide redirection.
  42  */
  43
  44
  45 /*
  46    Explode imploded (PKZIP method 6 compressed) data.  This compression
  47    method searches for as much of the current string of bytes (up to a length
  48    of ~320) in the previous 4K or 8K bytes.  If it doesn't find any matches
  49    (of at least length 2 or 3), it codes the next byte.  Otherwise, it codes
  50    the length of the matched string and its distance backwards from the
  51    current position.  Single bytes ("literals") are preceded by a one (a
  52    single bit) and are either uncoded (the eight bits go directly into the
  53    compressed stream for a total of nine bits) or Huffman coded with a
  54    supplied literal code tree.  If literals are coded, then the minimum match
  55    length is three, otherwise it is two.
  56
  57    There are therefore four kinds of imploded streams: 8K search with coded
  58    literals (min match = 3), 4K search with coded literals (min match = 3),
  59    8K with uncoded literals (min match = 2), and 4K with uncoded literals
  60    (min match = 2).  The kind of stream is identified in two bits of a
  61    general purpose bit flag that is outside of the compressed stream.
  62
  63    Distance-length pairs for matched strings are preceded by a zero bit (to
  64    distinguish them from literals) and are always coded.  The distance comes
  65    first and is either the low six (4K) or low seven (8K) bits of the
  66    distance (uncoded), followed by the high six bits of the distance coded.
  67    Then the length is six bits coded (0..63 + min match length), and if the
  68    maximum such length is coded, then it's followed by another eight bits
  69    (uncoded) to be added to the coded length.  This gives a match length
  70    range of 2..320 or 3..321 bytes.
  71
  72    The literal, length, and distance codes are all represented in a slightly
  73    compressed form themselves.  What is sent are the lengths of the codes for
  74    each value, which is sufficient to construct the codes.  Each byte of the
  75    code representation is the code length (the low four bits representing
  76    1..16), and the number of values sequentially with that length (the high
  77    four bits also representing 1..16).  There are 256 literal code values (if
  78    literals are coded), 64 length code values, and 64 distance code values,
  79    in that order at the beginning of the compressed stream.  Each set of code
  80    values is preceded (redundantly) with a byte indicating how many bytes are
  81    in the code description that follows, in the range 1..256.
  82
  83    The codes themselves are decoded using tables made by huft_build() from
  84    the bit lengths.  That routine and its comments are in the inflate.c
  85    module.
  86  */
  87
  88 #define UNZIP_INTERNAL
  89 #include "unzip.h"      /* must supply slide[] (uch) array and NEXTBYTE macro */
  90
  91 #ifndef WSIZE
  92 #  define WSIZE 0x8000  /* window size--must be a power of two, and */
  93 #endif                  /* at least 8K for zip's implode method */
  94
  95 #if (defined(DLL) && !defined(NO_SLIDE_REDIR))
  96 #  define wsize G._wsize
  97 #else
  98 #  define wsize WSIZE
  99 #endif
 100
 101 /* routines here */
 102 static int get_tree OF((__GPRO__ unsigned *l, unsigned n));
 103 static int explode_lit8 OF((__GPRO__ struct huft *tb, struct huft *tl,
 104                             struct huft *td, int bb, int bl, int bd));
 105 static int explode_lit4 OF((__GPRO__ struct huft *tb, struct huft *tl,
 106                             struct huft *td, int bb, int bl, int bd));
 107 static int explode_nolit8 OF((__GPRO__ struct huft *tl, struct huft *td,
 108                               int bl, int bd));
 109 static int explode_nolit4 OF((__GPRO__ struct huft *tl, struct huft *td,
 110                               int bl, int bd));
 111 int explode OF((__GPRO));
 112
 113
 114 /* The implode algorithm uses a sliding 4K or 8K byte window on the
 115    uncompressed stream to find repeated byte strings.  This is implemented
 116    here as a circular buffer.  The index is updated simply by incrementing
 117    and then and'ing with 0x0fff (4K-1) or 0x1fff (8K-1).  Here, the 32K
 118    buffer of inflate is used, and it works just as well to always have
 119    a 32K circular buffer, so the index is anded with 0x7fff.  This is
 120    done to allow the window to also be used as the output buffer. */
 121 /* This must be supplied in an external module useable like "uch slide[8192];"
 122    or "uch *slide;", where the latter would be malloc'ed.  In unzip, slide[]
 123    is actually a 32K area for use by inflate, which uses a 32K sliding window.
 124  */
 125
 126
 127 /* Tables for length and distance */
 128 static ZCONST ush cplen2[] =
 129         {2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17,
 130         18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34,
 131         35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51,
 132         52, 53, 54, 55, 56, 57, 58, 59, 60, 61, 62, 63, 64, 65};
 133 static ZCONST ush cplen3[] =
 134         {3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18,
 135         19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35,
 136         36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 52,
 137         53, 54, 55, 56, 57, 58, 59, 60, 61, 62, 63, 64, 65, 66};
 138 static ZCONST ush extra[] =
 139         {0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
 140         0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
 141         0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
 142         8};
 143 static ZCONST ush cpdist4[] =
 144         {1, 65, 129, 193, 257, 321, 385, 449, 513, 577, 641, 705,
 145         769, 833, 897, 961, 1025, 1089, 1153, 1217, 1281, 1345, 1409, 1473,
 146         1537, 1601, 1665, 1729, 1793, 1857, 1921, 1985, 2049, 2113, 2177,
 147         2241, 2305, 2369, 2433, 2497, 2561, 2625, 2689, 2753, 2817, 2881,
 148         2945, 3009, 3073, 3137, 3201, 3265, 3329, 3393, 3457, 3521, 3585,
 149         3649, 3713, 3777, 3841, 3905, 3969, 4033};
 150 static ZCONST ush cpdist8[] =
 151         {1, 129, 257, 385, 513, 641, 769, 897, 1025, 1153, 1281,
 152         1409, 1537, 1665, 1793, 1921, 2049, 2177, 2305, 2433, 2561, 2689,
 153         2817, 2945, 3073, 3201, 3329, 3457, 3585, 3713, 3841, 3969, 4097,
 154         4225, 4353, 4481, 4609, 4737, 4865, 4993, 5121, 5249, 5377, 5505,
 155         5633, 5761, 5889, 6017, 6145, 6273, 6401, 6529, 6657, 6785, 6913,
 156         7041, 7169, 7297, 7425, 7553, 7681, 7809, 7937, 8065};
 157
 158
 159 /* Macros for inflate() bit peeking and grabbing.
 160    The usage is:
 161
 162         NEEDBITS(j)
 163         x = b & mask_bits[j];
 164         DUMPBITS(j)
 165
 166    where NEEDBITS makes sure that b has at least j bits in it, and
 167    DUMPBITS removes the bits from b.  The macros use the variable k
 168    for the number of bits in b.  Normally, b and k are register
 169    variables for speed.
 170  */
 171
 172 #define NEEDBITS(n) {while(k<(n)){b|=((ulg)NEXTBYTE)<<k;k+=8;}}
 173 #define DUMPBITS(n) {b>>=(n);k-=(n);}
 174
 175
 176
 177 static int get_tree(__G__ l, n)
 178      __GDEF
 179 unsigned *l;            /* bit lengths */
 180 unsigned n;             /* number expected */
 181 /* Get the bit lengths for a code representation from the compressed
 182    stream.  If get_tree() returns 4, then there is an error in the data.
 183    Otherwise zero is returned. */
 184 {
 185   unsigned i;           /* bytes remaining in list */
 186   unsigned k;           /* lengths entered */
 187   unsigned j;           /* number of codes */
 188   unsigned b;           /* bit length for those codes */
 189
 190
 191   /* get bit lengths */
 192   i = NEXTBYTE + 1;                     /* length/count pairs to read */
 193   k = 0;                                /* next code */
 194   do {
 195     b = ((j = NEXTBYTE) & 0xf) + 1;     /* bits in code (1..16) */
 196     j = ((j & 0xf0) >> 4) + 1;          /* codes with those bits (1..16) */
 197     if (k + j > n)
 198       return 4;                         /* don't overflow l[] */
 199     do {
 200       l[k++] = b;
 201     } while (--j);
 202   } while (--i);
 203   return k != n ? 4 : 0;                /* should have read n of them */
 204 }
 205
 206
 207
 208 static int explode_lit8(__G__ tb, tl, td, bb, bl, bd)
 209      __GDEF
 210 struct huft *tb, *tl, *td;      /* literal, length, and distance tables */
 211 int bb, bl, bd;                 /* number of bits decoded by those */
 212 /* Decompress the imploded data using coded literals and an 8K sliding
 213    window. */
 214 {
 215   long s;               /* bytes to decompress */
 216   register unsigned e;  /* table entry flag/number of extra bits */
 217   unsigned n, d;        /* length and index for copy */
 218   unsigned w;           /* current window position */
 219   struct huft *t;       /* pointer to table entry */
 220   unsigned mb, ml, md;  /* masks for bb, bl, and bd bits */
 221   register ulg b;       /* bit buffer */
 222   register unsigned k;  /* number of bits in bit buffer */
 223   unsigned u;           /* true if unflushed */
 224
 225
 226   /* explode the coded data */
 227   b = k = w = 0;                /* initialize bit buffer, window */
 228   u = 1;                        /* buffer unflushed */
 229   mb = mask_bits[bb];           /* precompute masks for speed */
 230   ml = mask_bits[bl];
 231   md = mask_bits[bd];
 232   s = G.ucsize;
 233   while (s > 0)                 /* do until ucsize bytes uncompressed */
 234   {
 235     NEEDBITS(1)
 236     if (b & 1)                  /* then literal--decode it */
 237     {
 238       DUMPBITS(1)
 239       s--;
 240       NEEDBITS((unsigned)bb)    /* get coded literal */
 241       if ((e = (t = tb + ((~(unsigned)b) & mb))->e) > 16)
 242         do {
 243           if (e == 99)
 244             return 1;
 245           DUMPBITS(t->b)
 246           e -= 16;
 247           NEEDBITS(e)
 248         } while ((e = (t = t->v.t + ((~(unsigned)b) & mask_bits[e]))->e) > 16);
 249       DUMPBITS(t->b)
 250       redirSlide[w++] = (uch)t->v.n;
 251       if (w == wsize)
 252       {
 253         flush(__G__ redirSlide, (ulg)w, 0);
 254         w = u = 0;
 255       }
 256     }
 257     else                        /* else distance/length */
 258     {
 259       DUMPBITS(1)
 260       NEEDBITS(7)               /* get distance low bits */
 261       d = (unsigned)b & 0x7f;
 262       DUMPBITS(7)
 263       NEEDBITS((unsigned)bd)    /* get coded distance high bits */
 264       if ((e = (t = td + ((~(unsigned)b) & md))->e) > 16)
 265         do {
 266           if (e == 99)
 267             return 1;
 268           DUMPBITS(t->b)
 269           e -= 16;
 270           NEEDBITS(e)
 271         } while ((e = (t = t->v.t + ((~(unsigned)b) & mask_bits[e]))->e) > 16);
 272       DUMPBITS(t->b)
 273       d = w - d - t->v.n;       /* construct offset */
 274       NEEDBITS((unsigned)bl)    /* get coded length */
 275       if ((e = (t = tl + ((~(unsigned)b) & ml))->e) > 16)
 276         do {
 277           if (e == 99)
 278             return 1;
 279           DUMPBITS(t->b)
 280           e -= 16;
 281           NEEDBITS(e)
 282         } while ((e = (t = t->v.t + ((~(unsigned)b) & mask_bits[e]))->e) > 16);
 283       DUMPBITS(t->b)
 284       n = t->v.n;
 285       if (e)                    /* get length extra bits */
 286       {
 287         NEEDBITS(8)
 288         n += (unsigned)b & 0xff;
 289         DUMPBITS(8)
 290       }
 291
 292       /* do the copy */
 293       s -= n;
 294       do {
 295 #if (defined(DLL) && !defined(NO_SLIDE_REDIR))
 296         if (G.redirect_slide) {
 297           /* &= w/ wsize not needed and wrong if redirect */
 298           if (d >= wsize)
 299             return 1;
 300           n -= (e = (e = wsize - (d > w ? d : w)) > n ? n : e);
 301         } else
 302 #endif
 303         n -= (e = (e = wsize - ((d &= wsize-1) > w ? d : w)) > n ? n : e);
 304         if (u && w <= d)
 305         {
 306           memzero(redirSlide + w, e);
 307           w += e;
 308           d += e;
 309         }
 310         else
 311 #ifndef NOMEMCPY
 312           if (w - d >= e)       /* (this test assumes unsigned comparison) */
 313           {
 314             memcpy(redirSlide + w, redirSlide + d, e);
 315             w += e;
 316             d += e;
 317           }
 318           else                  /* do it slow to avoid memcpy() overlap */
 319 #endif /* !NOMEMCPY */
 320             do {
 321               redirSlide[w++] = redirSlide[d++];
 322             } while (--e);
 323         if (w == wsize)
 324         {
 325           flush(__G__ redirSlide, (ulg)w, 0);
 326           w = u = 0;
 327         }
 328       } while (n);
 329     }
 330   }
 331
 332   /* flush out redirSlide */
 333   flush(__G__ redirSlide, (ulg)w, 0);
 334   if (G.csize + G.incnt + (k >> 3))   /* should have read csize bytes, but */
 335   {                        /* sometimes read one too many:  k>>3 compensates */
 336     G.used_csize = G.lrec.csize - G.csize - G.incnt - (k >> 3);
 337     return 5;
 338   }
 339   return 0;
 340 }
 341
 342
 343
 344 static int explode_lit4(__G__ tb, tl, td, bb, bl, bd)
 345      __GDEF
 346 struct huft *tb, *tl, *td;      /* literal, length, and distance tables */
 347 int bb, bl, bd;                 /* number of bits decoded by those */
 348 /* Decompress the imploded data using coded literals and a 4K sliding
 349    window. */
 350 {
 351   long s;               /* bytes to decompress */
 352   register unsigned e;  /* table entry flag/number of extra bits */
 353   unsigned n, d;        /* length and index for copy */
 354   unsigned w;           /* current window position */
 355   struct huft *t;       /* pointer to table entry */
 356   unsigned mb, ml, md;  /* masks for bb, bl, and bd bits */
 357   register ulg b;       /* bit buffer */
 358   register unsigned k;  /* number of bits in bit buffer */
 359   unsigned u;           /* true if unflushed */
 360
 361
 362   /* explode the coded data */
 363   b = k = w = 0;                /* initialize bit buffer, window */
 364   u = 1;                        /* buffer unflushed */
 365   mb = mask_bits[bb];           /* precompute masks for speed */
 366   ml = mask_bits[bl];
 367   md = mask_bits[bd];
 368   s = G.ucsize;
 369   while (s > 0)                 /* do until ucsize bytes uncompressed */
 370   {
 371     NEEDBITS(1)
 372     if (b & 1)                  /* then literal--decode it */
 373     {
 374       DUMPBITS(1)
 375       s--;
 376       NEEDBITS((unsigned)bb)    /* get coded literal */
 377       if ((e = (t = tb + ((~(unsigned)b) & mb))->e) > 16)
 378         do {
 379           if (e == 99)
 380             return 1;
 381           DUMPBITS(t->b)
 382           e -= 16;
 383           NEEDBITS(e)
 384         } while ((e = (t = t->v.t + ((~(unsigned)b) & mask_bits[e]))->e) > 16);
 385       DUMPBITS(t->b)
 386       redirSlide[w++] = (uch)t->v.n;
 387       if (w == wsize)
 388       {
 389         flush(__G__ redirSlide, (ulg)w, 0);
 390         w = u = 0;
 391       }
 392     }
 393     else                        /* else distance/length */
 394     {
 395       DUMPBITS(1)
 396       NEEDBITS(6)               /* get distance low bits */
 397       d = (unsigned)b & 0x3f;
 398       DUMPBITS(6)
 399       NEEDBITS((unsigned)bd)    /* get coded distance high bits */
 400       if ((e = (t = td + ((~(unsigned)b) & md))->e) > 16)
 401         do {
 402           if (e == 99)
 403             return 1;
 404           DUMPBITS(t->b)
 405           e -= 16;
 406           NEEDBITS(e)
 407         } while ((e = (t = t->v.t + ((~(unsigned)b) & mask_bits[e]))->e) > 16);
 408       DUMPBITS(t->b)
 409       d = w - d - t->v.n;       /* construct offset */
 410       NEEDBITS((unsigned)bl)    /* get coded length */
 411       if ((e = (t = tl + ((~(unsigned)b) & ml))->e) > 16)
 412         do {
 413           if (e == 99)
 414             return 1;
 415           DUMPBITS(t->b)
 416           e -= 16;
 417           NEEDBITS(e)
 418         } while ((e = (t = t->v.t + ((~(unsigned)b) & mask_bits[e]))->e) > 16);
 419       DUMPBITS(t->b)
 420       n = t->v.n;
 421       if (e)                    /* get length extra bits */
 422       {
 423         NEEDBITS(8)
 424         n += (unsigned)b & 0xff;
 425         DUMPBITS(8)
 426       }
 427
 428       /* do the copy */
 429       s -= n;
 430       do {
 431 #if (defined(DLL) && !defined(NO_SLIDE_REDIR))
 432         if (G.redirect_slide) {
 433           /* &= w/ wsize not needed and wrong if redirect */
 434           if (d >= wsize)
 435             return 1;
 436           n -= (e = (e = wsize - (d > w ? d : w)) > n ? n : e);
 437         } else
 438 #endif
 439         n -= (e = (e = wsize - ((d &= wsize-1) > w ? d : w)) > n ? n : e);
 440         if (u && w <= d)
 441         {
 442           memzero(redirSlide + w, e);
 443           w += e;
 444           d += e;
 445         }
 446         else
 447 #ifndef NOMEMCPY
 448           if (w - d >= e)       /* (this test assumes unsigned comparison) */
 449           {
 450             memcpy(redirSlide + w, redirSlide + d, e);
 451             w += e;
 452             d += e;
 453           }
 454           else                  /* do it slow to avoid memcpy() overlap */
 455 #endif /* !NOMEMCPY */
 456             do {
 457               redirSlide[w++] = redirSlide[d++];
 458             } while (--e);
 459         if (w == wsize)
 460         {
 461           flush(__G__ redirSlide, (ulg)w, 0);
 462           w = u = 0;
 463         }
 464       } while (n);
 465     }
 466   }
 467
 468   /* flush out redirSlide */
 469   flush(__G__ redirSlide, (ulg)w, 0);
 470   if (G.csize + G.incnt + (k >> 3))   /* should have read csize bytes, but */
 471   {                        /* sometimes read one too many:  k>>3 compensates */
 472     G.used_csize = G.lrec.csize - G.csize - G.incnt - (k >> 3);
 473     return 5;
 474   }
 475   return 0;
 476 }
 477
 478
 479
 480 static int explode_nolit8(__G__ tl, td, bl, bd)
 481      __GDEF
 482 struct huft *tl, *td;   /* length and distance decoder tables */
 483 int bl, bd;             /* number of bits decoded by tl[] and td[] */
 484 /* Decompress the imploded data using uncoded literals and an 8K sliding
 485    window. */
 486 {
 487   long s;               /* bytes to decompress */
 488   register unsigned e;  /* table entry flag/number of extra bits */
 489   unsigned n, d;        /* length and index for copy */
 490   unsigned w;           /* current window position */
 491   struct huft *t;       /* pointer to table entry */
 492   unsigned ml, md;      /* masks for bl and bd bits */
 493   register ulg b;       /* bit buffer */
 494   register unsigned k;  /* number of bits in bit buffer */
 495   unsigned u;           /* true if unflushed */
 496
 497
 498   /* explode the coded data */
 499   b = k = w = 0;                /* initialize bit buffer, window */
 500   u = 1;                        /* buffer unflushed */
 501   ml = mask_bits[bl];           /* precompute masks for speed */
 502   md = mask_bits[bd];
 503   s = G.ucsize;
 504   while (s > 0)                 /* do until ucsize bytes uncompressed */
 505   {
 506     NEEDBITS(1)
 507     if (b & 1)                  /* then literal--get eight bits */
 508     {
 509       DUMPBITS(1)
 510       s--;
 511       NEEDBITS(8)
 512       redirSlide[w++] = (uch)b;
 513       if (w == wsize)
 514       {
 515         flush(__G__ redirSlide, (ulg)w, 0);
 516         w = u = 0;
 517       }
 518       DUMPBITS(8)
 519     }
 520     else                        /* else distance/length */
 521     {
 522       DUMPBITS(1)
 523       NEEDBITS(7)               /* get distance low bits */
 524       d = (unsigned)b & 0x7f;
 525       DUMPBITS(7)
 526       NEEDBITS((unsigned)bd)    /* get coded distance high bits */
 527       if ((e = (t = td + ((~(unsigned)b) & md))->e) > 16)
 528         do {
 529           if (e == 99)
 530             return 1;
 531           DUMPBITS(t->b)
 532           e -= 16;
 533           NEEDBITS(e)
 534         } while ((e = (t = t->v.t + ((~(unsigned)b) & mask_bits[e]))->e) > 16);
 535       DUMPBITS(t->b)
 536       d = w - d - t->v.n;       /* construct offset */
 537       NEEDBITS((unsigned)bl)    /* get coded length */
 538       if ((e = (t = tl + ((~(unsigned)b) & ml))->e) > 16)
 539         do {
 540           if (e == 99)
 541             return 1;
 542           DUMPBITS(t->b)
 543           e -= 16;
 544           NEEDBITS(e)
 545         } while ((e = (t = t->v.t + ((~(unsigned)b) & mask_bits[e]))->e) > 16);
 546       DUMPBITS(t->b)
 547       n = t->v.n;
 548       if (e)                    /* get length extra bits */
 549       {
 550         NEEDBITS(8)
 551         n += (unsigned)b & 0xff;
 552         DUMPBITS(8)
 553       }
 554
 555       /* do the copy */
 556       s -= n;
 557       do {
 558 #if (defined(DLL) && !defined(NO_SLIDE_REDIR))
 559         if (G.redirect_slide) {
 560           /* &= w/ wsize not needed and wrong if redirect */
 561           if (d >= wsize)
 562             return 1;
 563           n -= (e = (e = wsize - (d > w ? d : w)) > n ? n : e);
 564         } else
 565 #endif
 566         n -= (e = (e = wsize - ((d &= wsize-1) > w ? d : w)) > n ? n : e);
 567         if (u && w <= d)
 568         {
 569           memzero(redirSlide + w, e);
 570           w += e;
 571           d += e;
 572         }
 573         else
 574 #ifndef NOMEMCPY
 575           if (w - d >= e)       /* (this test assumes unsigned comparison) */
 576           {
 577             memcpy(redirSlide + w, redirSlide + d, e);
 578             w += e;
 579             d += e;
 580           }
 581           else                  /* do it slow to avoid memcpy() overlap */
 582 #endif /* !NOMEMCPY */
 583             do {
 584               redirSlide[w++] = redirSlide[d++];
 585             } while (--e);
 586         if (w == wsize)
 587         {
 588           flush(__G__ redirSlide, (ulg)w, 0);
 589           w = u = 0;
 590         }
 591       } while (n);
 592     }
 593   }
 594
 595   /* flush out redirSlide */
 596   flush(__G__ redirSlide, (ulg)w, 0);
 597   if (G.csize + G.incnt + (k >> 3))   /* should have read csize bytes, but */
 598   {                        /* sometimes read one too many:  k>>3 compensates */
 599     G.used_csize = G.lrec.csize - G.csize - G.incnt - (k >> 3);
 600     return 5;
 601   }
 602   return 0;
 603 }
 604
 605
 606
 607 static int explode_nolit4(__G__ tl, td, bl, bd)
 608      __GDEF
 609 struct huft *tl, *td;   /* length and distance decoder tables */
 610 int bl, bd;             /* number of bits decoded by tl[] and td[] */
 611 /* Decompress the imploded data using uncoded literals and a 4K sliding
 612    window. */
 613 {
 614   long s;               /* bytes to decompress */
 615   register unsigned e;  /* table entry flag/number of extra bits */
 616   unsigned n, d;        /* length and index for copy */
 617   unsigned w;           /* current window position */
 618   struct huft *t;       /* pointer to table entry */
 619   unsigned ml, md;      /* masks for bl and bd bits */
 620   register ulg b;       /* bit buffer */
 621   register unsigned k;  /* number of bits in bit buffer */
 622   unsigned u;           /* true if unflushed */
 623
 624
 625   /* explode the coded data */
 626   b = k = w = 0;                /* initialize bit buffer, window */
 627   u = 1;                        /* buffer unflushed */
 628   ml = mask_bits[bl];           /* precompute masks for speed */
 629   md = mask_bits[bd];
 630   s = G.ucsize;
 631   while (s > 0)                 /* do until ucsize bytes uncompressed */
 632   {
 633     NEEDBITS(1)
 634     if (b & 1)                  /* then literal--get eight bits */
 635     {
 636       DUMPBITS(1)
 637       s--;
 638       NEEDBITS(8)
 639       redirSlide[w++] = (uch)b;
 640       if (w == wsize)
 641       {
 642         flush(__G__ redirSlide, (ulg)w, 0);
 643         w = u = 0;
 644       }
 645       DUMPBITS(8)
 646     }
 647     else                        /* else distance/length */
 648     {
 649       DUMPBITS(1)
 650       NEEDBITS(6)               /* get distance low bits */
 651       d = (unsigned)b & 0x3f;
 652       DUMPBITS(6)
 653       NEEDBITS((unsigned)bd)    /* get coded distance high bits */
 654       if ((e = (t = td + ((~(unsigned)b) & md))->e) > 16)
 655         do {
 656           if (e == 99)
 657             return 1;
 658           DUMPBITS(t->b)
 659           e -= 16;
 660           NEEDBITS(e)
 661         } while ((e = (t = t->v.t + ((~(unsigned)b) & mask_bits[e]))->e) > 16);
 662       DUMPBITS(t->b)
 663       d = w - d - t->v.n;       /* construct offset */
 664       NEEDBITS((unsigned)bl)    /* get coded length */
 665       if ((e = (t = tl + ((~(unsigned)b) & ml))->e) > 16)
 666         do {
 667           if (e == 99)
 668             return 1;
 669           DUMPBITS(t->b)
 670           e -= 16;
 671           NEEDBITS(e)
 672         } while ((e = (t = t->v.t + ((~(unsigned)b) & mask_bits[e]))->e) > 16);
 673       DUMPBITS(t->b)
 674       n = t->v.n;
 675       if (e)                    /* get length extra bits */
 676       {
 677         NEEDBITS(8)
 678         n += (unsigned)b & 0xff;
 679         DUMPBITS(8)
 680       }
 681
 682       /* do the copy */
 683       s -= n;
 684       do {
 685 #if (defined(DLL) && !defined(NO_SLIDE_REDIR))
 686         if (G.redirect_slide) {
 687           /* &= w/ wsize not needed and wrong if redirect */
 688           if (d >= wsize)
 689             return 1;
 690           n -= (e = (e = wsize - (d > w ? d : w)) > n ? n : e);
 691         } else
 692 #endif
 693         n -= (e = (e = wsize - ((d &= wsize-1) > w ? d : w)) > n ? n : e);
 694         if (u && w <= d)
 695         {
 696           memzero(redirSlide + w, e);
 697           w += e;
 698           d += e;
 699         }
 700         else
 701 #ifndef NOMEMCPY
 702           if (w - d >= e)       /* (this test assumes unsigned comparison) */
 703           {
 704             memcpy(redirSlide + w, redirSlide + d, e);
 705             w += e;
 706             d += e;
 707           }
 708           else                  /* do it slow to avoid memcpy() overlap */
 709 #endif /* !NOMEMCPY */
 710             do {
 711               redirSlide[w++] = redirSlide[d++];
 712             } while (--e);
 713         if (w == wsize)
 714         {
 715           flush(__G__ redirSlide, (ulg)w, 0);
 716           w = u = 0;
 717         }
 718       } while (n);
 719     }
 720   }
 721
 722   /* flush out redirSlide */
 723   flush(__G__ redirSlide, (ulg)w, 0);
 724   if (G.csize + G.incnt + (k >> 3))   /* should have read csize bytes, but */
 725   {                        /* sometimes read one too many:  k>>3 compensates */
 726     G.used_csize = G.lrec.csize - G.csize - G.incnt - (k >> 3);
 727     return 5;
 728   }
 729   return 0;
 730 }
 731
 732
 733
 734 int explode(__G)
 735      __GDEF
 736 /* Explode an imploded compressed stream.  Based on the general purpose
 737    bit flag, decide on coded or uncoded literals, and an 8K or 4K sliding
 738    window.  Construct the literal (if any), length, and distance codes and
 739    the tables needed to decode them (using huft_build() from inflate.c),
 740    and call the appropriate routine for the type of data in the remainder
 741    of the stream.  The four routines are nearly identical, differing only
 742    in whether the literal is decoded or simply read in, and in how many
 743    bits are read in, uncoded, for the low distance bits. */
 744 {
 745   unsigned r;           /* return codes */
 746   struct huft *tb;      /* literal code table */
 747   struct huft *tl;      /* length code table */
 748   struct huft *td;      /* distance code table */
 749   int bb;               /* bits for tb */
 750   int bl;               /* bits for tl */
 751   int bd;               /* bits for td */
 752   unsigned l[256];      /* bit lengths for codes */
 753
 754 #if (defined(DLL) && !defined(NO_SLIDE_REDIR))
 755   if (G.redirect_slide)
 756     wsize = G.redirect_size, redirSlide = G.redirect_buffer;
 757   else
 758     wsize = WSIZE, redirSlide = slide;
 759 #endif
 760
 761   /* Tune base table sizes.  Note: I thought that to truly optimize speed,
 762      I would have to select different bl, bd, and bb values for different
 763      compressed file sizes.  I was surprised to find out that the values of
 764      7, 7, and 9 worked best over a very wide range of sizes, except that
 765      bd = 8 worked marginally better for large compressed sizes. */
 766   bl = 7;
 767   bd = (G.csize + G.incnt) > 200000L ? 8 : 7;
 768
 769
 770   /* With literal tree--minimum match length is 3 */
 771 #ifdef DEBUG
 772   G.hufts = 0;                    /* initialize huft's malloc'ed */
 773 #endif
 774   if (G.lrec.general_purpose_bit_flag & 4)
 775   {
 776     bb = 9;                     /* base table size for literals */
 777     if ((r = get_tree(__G__ l, 256)) != 0)
 778       return (int)r;
 779     if ((r = huft_build(__G__ l, 256, 256, NULL, NULL, &tb, &bb)) != 0)
 780     {
 781       if (r == 1)
 782         huft_free(tb);
 783       return (int)r;
 784     }
 785     if ((r = get_tree(__G__ l, 64)) != 0)
 786       return (int)r;
 787     if ((r = huft_build(__G__ l, 64, 0, cplen3, extra, &tl, &bl)) != 0)
 788     {
 789       if (r == 1)
 790         huft_free(tl);
 791       huft_free(tb);
 792       return (int)r;
 793     }
 794     if ((r = get_tree(__G__ l, 64)) != 0)
 795       return (int)r;
 796     if (G.lrec.general_purpose_bit_flag & 2)      /* true if 8K */
 797     {
 798       if ((r = huft_build(__G__ l, 64, 0, cpdist8, extra, &td, &bd)) != 0)
 799       {
 800         if (r == 1)
 801           huft_free(td);
 802         huft_free(tl);
 803         huft_free(tb);
 804         return (int)r;
 805       }
 806       r = explode_lit8(__G__ tb, tl, td, bb, bl, bd);
 807     }
 808     else                                        /* else 4K */
 809     {
 810       if ((r = huft_build(__G__ l, 64, 0, cpdist4, extra, &td, &bd)) != 0)
 811       {
 812         if (r == 1)
 813           huft_free(td);
 814         huft_free(tl);
 815         huft_free(tb);
 816         return (int)r;
 817       }
 818       r = explode_lit4(__G__ tb, tl, td, bb, bl, bd);
 819     }
 820     huft_free(td);
 821     huft_free(tl);
 822     huft_free(tb);
 823   }
 824   else
 825
 826
 827   /* No literal tree--minimum match length is 2 */
 828   {
 829     if ((r = get_tree(__G__ l, 64)) != 0)
 830       return (int)r;
 831     if ((r = huft_build(__G__ l, 64, 0, cplen2, extra, &tl, &bl)) != 0)
 832     {
 833       if (r == 1)
 834         huft_free(tl);
 835       return (int)r;
 836     }
 837     if ((r = get_tree(__G__ l, 64)) != 0)
 838       return (int)r;
 839     if (G.lrec.general_purpose_bit_flag & 2)      /* true if 8K */
 840     {
 841       if ((r = huft_build(__G__ l, 64, 0, cpdist8, extra, &td, &bd)) != 0)
 842       {
 843         if (r == 1)
 844           huft_free(td);
 845         huft_free(tl);
 846         return (int)r;
 847       }
 848       r = explode_nolit8(__G__ tl, td, bl, bd);
 849     }
 850     else                                        /* else 4K */
 851     {
 852       if ((r = huft_build(__G__ l, 64, 0, cpdist4, extra, &td, &bd)) != 0)
 853       {
 854         if (r == 1)
 855           huft_free(td);
 856         huft_free(tl);
 857         return (int)r;
 858       }
 859       r = explode_nolit4(__G__ tl, td, bl, bd);
 860     }
 861     huft_free(td);
 862     huft_free(tl);
 863   }
 864   Trace((stderr, "<%u > ", G.hufts));
 865   return (int)r;
 866 }
 867
 868 /* so explode.c and inflate.c can be compiled together into one object: */
 869 #undef NEXTBYTE
 870 #undef NEEDBITS
 871 #undef DUMPBITS