src/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 #if defined(__VISAGECPP__) /* Visualage can't handle this antiquated interface */
  59 inflate_codes_statef* inflate_codes_new(uInt bl, uInt bd, inflate_huft* tl, inflate_huft* td, z_streamp z)
  60 #else
  61 inflate_codes_statef *inflate_codes_new(bl, bd, tl, td, z)
  62 uInt bl, bd;
  63 inflate_huft *tl;
  64 inflate_huft *td; /* need separate declaration for Borland C++ */
  65 z_streamp z;
  66 #endif
  67 {
  68   inflate_codes_statef *c;
  69
  70   if ((c = (inflate_codes_statef *)
  71        ZALLOC(z,1,sizeof(struct inflate_codes_state))) != Z_NULL)
  72   {
  73     c->mode = START;
  74     c->lbits = (Byte)bl;
  75     c->dbits = (Byte)bd;
  76     c->ltree = tl;
  77     c->dtree = td;
  78     Tracev((stderr, "inflate:       codes new\n"));
  79   }
  80   return c;
  81 }
  82
  83 #if defined(__VISAGECPP__) /* Visualage can't handle this antiquated interface */
  84 int inflate_codes(inflate_blocks_statef* s, z_streamp z, int r)
  85 #else
  86 int inflate_codes(s, z, r)
  87 inflate_blocks_statef *s;
  88 z_streamp z;
  89 int r;
  90 #endif
  91 {
  92   uInt j;               /* temporary storage */
  93   inflate_huft *t;      /* temporary pointer */
  94   uInt e;               /* extra bits or operation */
  95   uLong b;              /* bit buffer */
  96   uInt k;               /* bits in bit buffer */
  97   Bytef *p;             /* input data pointer */
  98   uInt n;               /* bytes available there */
  99   Bytef *q;             /* output window write pointer */
 100   uInt m;               /* bytes to end of window or read pointer */
 101   Bytef *f;             /* pointer to copy strings from */
 102   inflate_codes_statef *c = s->sub.decode.codes;  /* codes state */
 103
 104   /* copy input/output information to locals (UPDATE macro restores) */
 105   LOAD
 106
 107   /* process input and output based on current state */
 108   while (1) switch (c->mode)
 109   {             /* waiting for "i:"=input, "o:"=output, "x:"=nothing */
 110     case START:         /* x: set up for LEN */
 111 #ifndef SLOW
 112       if (m >= 258 && n >= 10)
 113       {
 114         UPDATE
 115         r = inflate_fast(c->lbits, c->dbits, c->ltree, c->dtree, s, z);
 116         LOAD
 117         if (r != Z_OK)
 118         {
 119           c->mode = r == Z_STREAM_END ? WASH : BADCODE;
 120           break;
 121         }
 122       }
 123 #endif /* !SLOW */
 124       c->sub.code.need = c->lbits;
 125       c->sub.code.tree = c->ltree;
 126       c->mode = LEN;
 127     case LEN:           /* i: get length/literal/eob next */
 128       j = c->sub.code.need;
 129       NEEDBITS(j)
 130       t = c->sub.code.tree + ((uInt)b & inflate_mask[j]);
 131       DUMPBITS(t->bits)
 132       e = (uInt)(t->exop);
 133       if (e == 0)               /* literal */
 134       {
 135         c->sub.lit = t->base;
 136         Tracevv((stderr, t->base >= 0x20 && t->base < 0x7f ?
 137                  "inflate:         literal '%c'\n" :
 138                  "inflate:         literal 0x%02x\n", t->base));
 139         c->mode = LIT;
 140         break;
 141       }
 142       if (e & 16)               /* length */
 143       {
 144         c->sub.copy.get = e & 15;
 145         c->len = t->base;
 146         c->mode = LENEXT;
 147         break;
 148       }
 149       if ((e & 64) == 0)        /* next table */
 150       {
 151         c->sub.code.need = e;
 152         c->sub.code.tree = t + t->base;
 153         break;
 154       }
 155       if (e & 32)               /* end of block */
 156       {
 157         Tracevv((stderr, "inflate:         end of block\n"));
 158         c->mode = WASH;
 159         break;
 160       }
 161       c->mode = BADCODE;        /* invalid code */
 162       z->msg = (char*)"invalid literal/length code";
 163       r = Z_DATA_ERROR;
 164       LEAVE
 165     case LENEXT:        /* i: getting length extra (have base) */
 166       j = c->sub.copy.get;
 167       NEEDBITS(j)
 168       c->len += (uInt)b & inflate_mask[j];
 169       DUMPBITS(j)
 170       c->sub.code.need = c->dbits;
 171       c->sub.code.tree = c->dtree;
 172       Tracevv((stderr, "inflate:         length %u\n", c->len));
 173       c->mode = DIST;
 174     case DIST:          /* i: get distance next */
 175       j = c->sub.code.need;
 176       NEEDBITS(j)
 177       t = c->sub.code.tree + ((uInt)b & inflate_mask[j]);
 178       DUMPBITS(t->bits)
 179       e = (uInt)(t->exop);
 180       if (e & 16)               /* distance */
 181       {
 182         c->sub.copy.get = e & 15;
 183         c->sub.copy.dist = t->base;
 184         c->mode = DISTEXT;
 185         break;
 186       }
 187       if ((e & 64) == 0)        /* next table */
 188       {
 189         c->sub.code.need = e;
 190         c->sub.code.tree = t + t->base;
 191         break;
 192       }
 193       c->mode = BADCODE;        /* invalid code */
 194       z->msg = (char*)"invalid distance code";
 195       r = Z_DATA_ERROR;
 196       LEAVE
 197     case DISTEXT:       /* i: getting distance extra */
 198       j = c->sub.copy.get;
 199       NEEDBITS(j)
 200       c->sub.copy.dist += (uInt)b & inflate_mask[j];
 201       DUMPBITS(j)
 202       Tracevv((stderr, "inflate:         distance %u\n", c->sub.copy.dist));
 203       c->mode = COPY;
 204     case COPY:          /* o: copying bytes in window, waiting for space */
 205       f = q - c->sub.copy.dist;
 206       while (f < s->window)             /* modulo window size-"while" instead */
 207         f += s->end - s->window;        /* of "if" handles invalid distances */
 208       while (c->len)
 209       {
 210         NEEDOUT
 211         OUTBYTE(*f++)
 212         if (f == s->end)
 213           f = s->window;
 214         c->len--;
 215       }
 216       c->mode = START;
 217       break;
 218     case LIT:           /* o: got literal, waiting for output space */
 219       NEEDOUT
 220       OUTBYTE(c->sub.lit)
 221       c->mode = START;
 222       break;
 223     case WASH:          /* o: got eob, possibly more output */
 224       if (k > 7)        /* return unused byte, if any */
 225       {
 226         Assert(k < 16, "inflate_codes grabbed too many bytes")
 227         k -= 8;
 228         n++;
 229         p--;            /* can always return one */
 230       }
 231       FLUSH
 232       if (s->read != s->write)
 233         LEAVE
 234       c->mode = END;
 235     case END:
 236       r = Z_STREAM_END;
 237       LEAVE
 238     case BADCODE:       /* x: got error */
 239       r = Z_DATA_ERROR;
 240       LEAVE
 241     default:
 242       r = Z_STREAM_ERROR;
 243       LEAVE
 244   }
 245 #ifdef NEED_DUMMY_RETURN
 246   return Z_STREAM_ERROR;  /* Some dumb compilers complain without this */
 247 #endif
 248 }
 249
 250 #if defined(__VISAGECPP__) /* Visualage can't handle this antiquated interface */
 251 void inflate_codes_free(inflate_codes_statef* c, z_streamp z)
 252 #else
 253 void inflate_codes_free(c, z)
 254 inflate_codes_statef *c;
 255 z_streamp z;
 256 #endif
 257 {
 258   ZFREE(z, c);
 259   Tracev((stderr, "inflate:       codes free\n"));
 260 }