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
12 /* simplify the use of the inflate_huft type with some defines */
13 #define exop word.what.Exop
14 #define bits word.what.Bits
16 typedef enum { /* waiting for "i:"=input, "o:"=output, "x:"=nothing */
17 START, /* x: set up for LEN */
18 LEN, /* i: get length/literal/eob next */
19 LENEXT, /* i: getting length extra (have base) */
20 DIST, /* i: get distance next */
21 DISTEXT, /* i: getting distance extra */
22 COPY, /* o: copying bytes in window, waiting for space */
23 LIT, /* o: got literal, waiting for output space */
24 WASH, /* o: got eob, possibly still output waiting */
25 END, /* x: got eob and all data flushed */
26 BADCODE} /* x: got error */
29 /* inflate codes private state */
30 struct inflate_codes_state {
33 inflate_codes_mode mode; /* current inflate_codes mode */
35 /* mode dependent information */
39 inflate_huft *tree; /* pointer into tree */
40 uInt need; /* bits needed */
41 } code; /* if LEN or DIST, where in tree */
42 uInt lit; /* if LIT, literal */
44 uInt get; /* bits to get for extra */
45 uInt dist; /* distance back to copy from */
46 } copy; /* if EXT or COPY, where and how much */
49 /* mode independent information */
50 Byte lbits; /* ltree bits decoded per branch */
51 Byte dbits; /* dtree bits decoder per branch */
52 inflate_huft *ltree; /* literal/length/eob tree */
53 inflate_huft *dtree; /* distance tree */
58 local inflate_codes_statef *inflate_codes_new( /* bl, bd, tl, td, z) */
61 inflate_huft *td, /* need separate declaration for Borland C++ */
64 inflate_codes_statef *c;
66 if ((c = (inflate_codes_statef *)
67 ZALLOC(z,1,sizeof(struct inflate_codes_state))) != Z_NULL)
74 Tracev((stderr, "inflate: codes new\n"));
80 local int inflate_codes( /* s, z, r) */
81 inflate_blocks_statef *s,
85 uInt j; /* temporary storage */
86 inflate_huft *t; /* temporary pointer */
87 uInt e; /* extra bits or operation */
88 uLong b; /* bit buffer */
89 uInt k; /* bits in bit buffer */
90 Bytef *p; /* input data pointer */
91 uInt n; /* bytes available there */
92 Bytef *q; /* output window write pointer */
93 uInt m; /* bytes to end of window or read pointer */
94 Bytef *f; /* pointer to copy strings from */
95 inflate_codes_statef *c = s->sub.decode.codes; /* codes state */
97 /* copy input/output information to locals (UPDATE macro restores) */
100 /* process input and output based on current state */
101 while (1) switch (c->mode)
102 { /* waiting for "i:"=input, "o:"=output, "x:"=nothing */
103 case START: /* x: set up for LEN */
105 if (m >= 258 && n >= 10)
108 r = inflate_fast(c->lbits, c->dbits, c->ltree, c->dtree, s, z);
112 c->mode = r == Z_STREAM_END ? WASH : BADCODE;
117 c->sub.code.need = c->lbits;
118 c->sub.code.tree = c->ltree;
120 case LEN: /* i: get length/literal/eob next */
121 j = c->sub.code.need;
123 t = c->sub.code.tree + ((uInt)b & inflate_mask[j]);
126 if (e == 0) /* literal */
128 c->sub.lit = t->base;
129 Tracevv((stderr, t->base >= 0x20 && t->base < 0x7f ?
130 "inflate: literal '%c'\n" :
131 "inflate: literal 0x%02x\n", t->base));
135 if (e & 16) /* length */
137 c->sub.copy.get = e & 15;
142 if ((e & 64) == 0) /* next table */
144 c->sub.code.need = e;
145 c->sub.code.tree = t + t->base;
148 if (e & 32) /* end of block */
150 Tracevv((stderr, "inflate: end of block\n"));
154 c->mode = BADCODE; /* invalid code */
155 z->msg = (char*)"invalid literal/length code";
158 case LENEXT: /* i: getting length extra (have base) */
161 c->len += (uInt)b & inflate_mask[j];
163 c->sub.code.need = c->dbits;
164 c->sub.code.tree = c->dtree;
165 Tracevv((stderr, "inflate: length %u\n", c->len));
167 case DIST: /* i: get distance next */
168 j = c->sub.code.need;
170 t = c->sub.code.tree + ((uInt)b & inflate_mask[j]);
173 if (e & 16) /* distance */
175 c->sub.copy.get = e & 15;
176 c->sub.copy.dist = t->base;
180 if ((e & 64) == 0) /* next table */
182 c->sub.code.need = e;
183 c->sub.code.tree = t + t->base;
186 c->mode = BADCODE; /* invalid code */
187 z->msg = (char*)"invalid distance code";
190 case DISTEXT: /* i: getting distance extra */
193 c->sub.copy.dist += (uInt)b & inflate_mask[j];
195 Tracevv((stderr, "inflate: distance %u\n", c->sub.copy.dist));
197 case COPY: /* o: copying bytes in window, waiting for space */
198 f = q - c->sub.copy.dist;
199 while (f < s->window) /* modulo window size-"while" instead */
200 f += s->end - s->window; /* of "if" handles invalid distances */
211 case LIT: /* o: got literal, waiting for output space */
216 case WASH: /* o: got eob, possibly more output */
217 if (k > 7) /* return unused byte, if any */
219 Assert(k < 16, "inflate_codes grabbed too many bytes")
222 p--; /* can always return one */
225 if (s->read != s->write)
231 case BADCODE: /* x: got error */
238 #ifdef NEED_DUMMY_RETURN
239 return Z_STREAM_ERROR; /* Some dumb compilers complain without this */
244 local void inflate_codes_free( /* c, z) */
245 inflate_codes_statef *c,
249 Tracev((stderr, "inflate: codes free\n"));