zlib/infcodes.c

   1 /* infcodes.c -- process literals and length/distance pairs
   2  * Copyright (C) 1995-2002 Mark Adler
   3  * For conditions of distribution and use, see copyright notice in zlib.h
   4  */
   5
   6 #include "zutil.h"
   7 #include "inftrees.h"
   8 #include "infblock.h"
   9 #include "infcodes.h"
  10 #include "infutil.h"
  11 #include "inffast.h"
  12
  13 /* simplify the use of the inflate_huft type with some defines */
  14 #define exop word.what.Exop
  15 #define bits word.what.Bits
  16
  17 typedef enum {        /* waiting for "i:"=input, "o:"=output, "x:"=nothing */
  18       START,    /* x: set up for LEN */
  19       LEN,      /* i: get length/literal/eob next */
  20       LENEXT,   /* i: getting length extra (have base) */
  21       DIST,     /* i: get distance next */
  22       DISTEXT,  /* i: getting distance extra */
  23       COPY,     /* o: copying bytes in window, waiting for space */
  24       LIT,      /* o: got literal, waiting for output space */
  25       WASH,     /* o: got eob, possibly still output waiting */
  26       END,      /* x: got eob and all data flushed */
  27       BADCODE}  /* x: got error */
  28 inflate_codes_mode;
  29
  30 /* inflate codes private state */
  31 struct inflate_codes_state {
  32
  33   /* mode */
  34   inflate_codes_mode mode;      /* current inflate_codes mode */
  35
  36   /* mode dependent information */
  37   uInt len;
  38   union {
  39     struct {
  40       inflate_huft *tree;       /* pointer into tree */
  41       uInt need;                /* bits needed */
  42     } code;             /* if LEN or DIST, where in tree */
  43     uInt lit;           /* if LIT, literal */
  44     struct {
  45       uInt get;                 /* bits to get for extra */
  46       uInt dist;                /* distance back to copy from */
  47     } copy;             /* if EXT or COPY, where and how much */
  48   } sub;                /* submode */
  49
  50   /* mode independent information */
  51   Byte lbits;           /* ltree bits decoded per branch */
  52   Byte dbits;           /* dtree bits decoder per branch */
  53   inflate_huft *ltree;          /* literal/length/eob tree */
  54   inflate_huft *dtree;          /* distance tree */
  55
  56 };
  57
  58
  59 inflate_codes_statef *inflate_codes_new(bl, bd, tl, td, z)
  60 uInt bl, bd;
  61 inflate_huft *tl;
  62 inflate_huft *td; /* need separate declaration for Borland C++ */
  63 z_streamp z;
  64 {
  65   inflate_codes_statef *c;
  66
  67   if ((c = (inflate_codes_statef *)
  68        ZALLOC(z,1,sizeof(struct inflate_codes_state))) != Z_NULL)
  69   {
  70     c->mode = START;
  71     c->lbits = (Byte)bl;
  72     c->dbits = (Byte)bd;
  73     c->ltree = tl;
  74     c->dtree = td;
  75     Tracev((stderr, "inflate:       codes new\n"));
  76   }
  77   return c;
  78 }
  79
  80
  81 int inflate_codes(s, z, r)
  82 inflate_blocks_statef *s;
  83 z_streamp z;
  84 int r;
  85 {
  86   uInt j;               /* temporary storage */
  87   inflate_huft *t;      /* temporary pointer */
  88   uInt e;               /* extra bits or operation */
  89   uLong b;              /* bit buffer */
  90   uInt k;               /* bits in bit buffer */
  91   Bytef *p;             /* input data pointer */
  92   uInt n;               /* bytes available there */
  93   Bytef *q;             /* output window write pointer */
  94   uInt m;               /* bytes to end of window or read pointer */
  95   Bytef *f;             /* pointer to copy strings from */
  96   inflate_codes_statef *c = s->sub.decode.codes;  /* codes state */
  97
  98   /* copy input/output information to locals (UPDATE macro restores) */
  99   LOAD
 100
 101   /* process input and output based on current state */
 102   while (1) switch (c->mode)
 103   {             /* waiting for "i:"=input, "o:"=output, "x:"=nothing */
 104     case START:         /* x: set up for LEN */
 105 #ifndef SLOW
 106       if (m >= 258 && n >= 10)
 107       {
 108         UPDATE
 109         r = inflate_fast(c->lbits, c->dbits, c->ltree, c->dtree, s, z);
 110         LOAD
 111         if (r != Z_OK)
 112         {
 113           c->mode = r == Z_STREAM_END ? WASH : BADCODE;
 114           break;
 115         }
 116       }
 117 #endif /* !SLOW */
 118       c->sub.code.need = c->lbits;
 119       c->sub.code.tree = c->ltree;
 120       c->mode = LEN;
 121     case LEN:           /* i: get length/literal/eob next */
 122       j = c->sub.code.need;
 123       NEEDBITS(j)
 124       t = c->sub.code.tree + ((uInt)b & inflate_mask[j]);
 125       DUMPBITS(t->bits)
 126       e = (uInt)(t->exop);
 127       if (e == 0)               /* literal */
 128       {
 129         c->sub.lit = t->base;
 130         Tracevv((stderr, t->base >= 0x20 && t->base < 0x7f ?
 131                  "inflate:         literal '%c'\n" :
 132                  "inflate:         literal 0x%02x\n", t->base));
 133         c->mode = LIT;
 134         break;
 135       }
 136       if (e & 16)               /* length */
 137       {
 138         c->sub.copy.get = e & 15;
 139         c->len = t->base;
 140         c->mode = LENEXT;
 141         break;
 142       }
 143       if ((e & 64) == 0)        /* next table */
 144       {
 145         c->sub.code.need = e;
 146         c->sub.code.tree = t + t->base;
 147         break;
 148       }
 149       if (e & 32)               /* end of block */
 150       {
 151         Tracevv((stderr, "inflate:         end of block\n"));
 152         c->mode = WASH;
 153         break;
 154       }
 155       c->mode = BADCODE;        /* invalid code */
 156       z->msg = (char*)"invalid literal/length code";
 157       r = Z_DATA_ERROR;
 158       LEAVE
 159     case LENEXT:        /* i: getting length extra (have base) */
 160       j = c->sub.copy.get;
 161       NEEDBITS(j)
 162       c->len += (uInt)b & inflate_mask[j];
 163       DUMPBITS(j)
 164       c->sub.code.need = c->dbits;
 165       c->sub.code.tree = c->dtree;
 166       Tracevv((stderr, "inflate:         length %u\n", c->len));
 167       c->mode = DIST;
 168     case DIST:          /* i: get distance next */
 169       j = c->sub.code.need;
 170       NEEDBITS(j)
 171       t = c->sub.code.tree + ((uInt)b & inflate_mask[j]);
 172       DUMPBITS(t->bits)
 173       e = (uInt)(t->exop);
 174       if (e & 16)               /* distance */
 175       {
 176         c->sub.copy.get = e & 15;
 177         c->sub.copy.dist = t->base;
 178         c->mode = DISTEXT;
 179         break;
 180       }
 181       if ((e & 64) == 0)        /* next table */
 182       {
 183         c->sub.code.need = e;
 184         c->sub.code.tree = t + t->base;
 185         break;
 186       }
 187       c->mode = BADCODE;        /* invalid code */
 188       z->msg = (char*)"invalid distance code";
 189       r = Z_DATA_ERROR;
 190       LEAVE
 191     case DISTEXT:       /* i: getting distance extra */
 192       j = c->sub.copy.get;
 193       NEEDBITS(j)
 194       c->sub.copy.dist += (uInt)b & inflate_mask[j];
 195       DUMPBITS(j)
 196       Tracevv((stderr, "inflate:         distance %u\n", c->sub.copy.dist));
 197       c->mode = COPY;
 198     case COPY:          /* o: copying bytes in window, waiting for space */
 199       f = q - c->sub.copy.dist;
 200       while (f < s->window)             /* modulo window size-"while" instead */
 201         f += s->end - s->window;        /* of "if" handles invalid distances */
 202       while (c->len)
 203       {
 204         NEEDOUT
 205         OUTBYTE(*f++)
 206         if (f == s->end)
 207           f = s->window;
 208         c->len--;
 209       }
 210       c->mode = START;
 211       break;
 212     case LIT:           /* o: got literal, waiting for output space */
 213       NEEDOUT
 214       OUTBYTE(c->sub.lit)
 215       c->mode = START;
 216       break;
 217     case WASH:          /* o: got eob, possibly more output */
 218       if (k > 7)        /* return unused byte, if any */
 219       {
 220         Assert(k < 16, "inflate_codes grabbed too many bytes")
 221         k -= 8;
 222         n++;
 223         p--;            /* can always return one */
 224       }
 225       FLUSH
 226       if (s->read != s->write)
 227         LEAVE
 228       c->mode = END;
 229     case END:
 230       r = Z_STREAM_END;
 231       LEAVE
 232     case BADCODE:       /* x: got error */
 233       r = Z_DATA_ERROR;
 234       LEAVE
 235     default:
 236       r = Z_STREAM_ERROR;
 237       LEAVE
 238   }
 239 #ifdef NEED_DUMMY_RETURN
 240   return Z_STREAM_ERROR;  /* Some dumb compilers complain without this */
 241 #endif
 242 }
 243
 244
 245 void inflate_codes_free(c, z)
 246 inflate_codes_statef *c;
 247 z_streamp z;
 248 {
 249   ZFREE(z, c);
 250   Tracev((stderr, "inflate:       codes free\n"));
 251 }