c62d2810 |
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 | |
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 | f = q - c->sub.copy.dist; |
200 | while (f < s->window) /* modulo window size-"while" instead */ |
201 | f += s->end - s->window; /* of "if" handles invalid distances */ |
202 | while (c->len) |
203 | { |
204 | NEEDOUT |
205 | OUTBYTE(*f++) |
206 | if (f == s->end) |
207 | f = s->window; |
208 | c->len--; |
209 | } |
210 | c->mode = START; |
211 | break; |
212 | case LIT: /* o: got literal, waiting for output space */ |
213 | NEEDOUT |
214 | OUTBYTE(c->sub.lit) |
215 | c->mode = START; |
216 | break; |
217 | case WASH: /* o: got eob, possibly more output */ |
218 | if (k > 7) /* return unused byte, if any */ |
219 | { |
220 | Assert(k < 16, "inflate_codes grabbed too many bytes") |
221 | k -= 8; |
222 | n++; |
223 | p--; /* can always return one */ |
224 | } |
225 | FLUSH |
226 | if (s->read != s->write) |
227 | LEAVE |
228 | c->mode = END; |
229 | case END: |
230 | r = Z_STREAM_END; |
231 | LEAVE |
232 | case BADCODE: /* x: got error */ |
233 | r = Z_DATA_ERROR; |
234 | LEAVE |
235 | default: |
236 | r = Z_STREAM_ERROR; |
237 | LEAVE |
238 | } |
239 | #ifdef NEED_DUMMY_RETURN |
240 | return Z_STREAM_ERROR; /* Some dumb compilers complain without this */ |
241 | #endif |
242 | } |
243 | |
244 | |
245 | void inflate_codes_free(c, z) |
246 | inflate_codes_statef *c; |
247 | z_streamp z; |
248 | { |
249 | ZFREE(z, c); |
250 | Tracev((stderr, "inflate: codes free\n")); |
251 | } |