1 /* infcodes.c -- process literals and length/distance pairs
2 * Copyright (C) 1995 Mark Adler
3 * For conditions of distribution and use, see copyright notice in zlib.h
13 /* simplify the use of the inflate_huft type with some defines */
14 #define base more.Base
15 #define next more.Next
16 #define exop word.what.Exop
17 #define bits word.what.Bits
19 /* inflate codes private state */
20 struct inflate_codes_state {
23 enum { /* waiting for "i:"=input, "o:"=output, "x:"=nothing */
24 START, /* x: set up for LEN */
25 LEN, /* i: get length/literal/eob next */
26 LENEXT, /* i: getting length extra (have base) */
27 DIST, /* i: get distance next */
28 DISTEXT, /* i: getting distance extra */
29 COPY, /* o: copying bytes in window, waiting for space */
30 LIT, /* o: got literal, waiting for output space */
31 WASH, /* o: got eob, possibly still output waiting */
32 END, /* x: got eob and all data flushed */
33 BADCODE} /* x: got error */
34 mode; /* current inflate_codes mode */
36 /* mode dependent information */
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 */
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 */
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 */
59 inflate_codes_statef *inflate_codes_new(bl, bd, tl, td, z)
61 inflate_huft *tl, *td;
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 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->next;
148 if (e & 32) /* end of block */
150 Tracevv((stderr, "inflate: end of block\n"));
154 c->mode = BADCODE; /* invalid code */
155 z->msg = "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->next;
186 c->mode = BADCODE; /* invalid code */
187 z->msg = "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 #ifndef __TURBOC__ /* Turbo C bug for following expression */
199 f = (uInt)(q - s->window) < c->sub.copy.dist ?
200 s->end - (c->sub.copy.dist - (q - s->window)) :
201 q - c->sub.copy.dist;
203 f = q - c->sub.copy.dist;
204 if ((uInt)(q - s->window) < c->sub.copy.dist)
205 f = s->end - (c->sub.copy.dist - (uInt)(q - s->window));
217 case LIT: /* o: got literal, waiting for output space */
222 case WASH: /* o: got eob, possibly more output */
224 if (s->read != s->write)
230 case BADCODE: /* x: got error */
240 void inflate_codes_free(c, z)
241 inflate_codes_statef *c;
245 Tracev((stderr, "inflate: codes free\n"));