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comparison lib/zlib/infcodes.c @ 0:8b8875f5b359

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author Nomad
date Fri, 05 Oct 2012 16:07:14 +0200
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-1:000000000000 0:8b8875f5b359
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
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 #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
251 void inflate_codes_free(c, z)
252 inflate_codes_statef *c;
253 z_streamp z;
254 {
255 ZFREE(z, c);
256 Tracev((stderr, "inflate: codes free\n"));
257 }