1/* infcodes.c -- process literals and length/distance pairs
2 * Copyright (C) 1995-1998 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
17typedef 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 */
28inflate_codes_mode;
29
30/* inflate codes private state */
31struct 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
59inflate_codes_statef *inflate_codes_new(bl, bd, tl, td, z)
60uInt bl, bd;
61inflate_huft *tl;
62inflate_huft *td; /* need separate declaration for Borland C++ */
63z_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
81int inflate_codes(s, z, r)
82inflate_blocks_statef *s;
83z_streamp z;
84int 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#ifndef __TURBOC__ /* Turbo C bug for following expression */
200      f = (uInt)(q - s->window) < c->sub.copy.dist ?
201          s->end - (c->sub.copy.dist - (q - s->window)) :
202          q - c->sub.copy.dist;
203#else
204      f = q - c->sub.copy.dist;
205      if ((uInt)(q - s->window) < c->sub.copy.dist)
206        f = s->end - (c->sub.copy.dist - (uInt)(q - s->window));
207#endif
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
251void inflate_codes_free(c, z)
252inflate_codes_statef *c;
253z_streamp z;
254{
255  ZFREE(z, c);
256  Tracev((stderr, "inflate:       codes free\n"));
257}
258