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comparison zlib/infcodes.c @ 3:5a977ccbc7a9 default tip

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author darius
date Sat, 06 Dec 1997 05:41:29 +0000
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2:fba0b6e6cdc7 3:5a977ccbc7a9
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
4 */
5
6 #include "zutil.h"
7 #include "inftrees.h"
8 #include "infutil.h"
9 #include "inffast.h"
10 #include "infcodes.h"
11
12 /* simplify the use of the inflate_huft type with some defines */
13 #define base more.Base
14 #define next more.Next
15 #define exop word.what.Exop
16 #define bits word.what.Bits
17
18 /* inflate codes private state */
19 struct inflate_codes_state {
20
21 /* mode */
22 enum { /* waiting for "i:"=input, "o:"=output, "x:"=nothing */
23 START, /* x: set up for LEN */
24 LEN, /* i: get length/literal/eob next */
25 LENEXT, /* i: getting length extra (have base) */
26 DIST, /* i: get distance next */
27 DISTEXT, /* i: getting distance extra */
28 COPY, /* o: copying bytes in window, waiting for space */
29 LIT, /* o: got literal, waiting for output space */
30 WASH, /* o: got eob, possibly still output waiting */
31 END, /* x: got eob and all data flushed */
32 BADCODE} /* x: got error */
33 mode; /* current inflate_codes mode */
34
35 /* mode dependent information */
36 uInt len;
37 union {
38 struct {
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 */
43 struct {
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 */
47 } sub; /* submode */
48
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 */
54
55 };
56
57
58 struct inflate_codes_state *inflate_codes_new(bl, bd, tl, td, z)
59 uInt bl, bd;
60 inflate_huft *tl, *td;
61 z_stream *z;
62 {
63 struct inflate_codes_state *c;
64
65 if ((c = (struct inflate_codes_state *)
66 ZALLOC(z,1,sizeof(struct inflate_codes_state))) != Z_NULL)
67 {
68 c->mode = START;
69 c->lbits = (Byte)bl;
70 c->dbits = (Byte)bd;
71 c->ltree = tl;
72 c->dtree = td;
73 Tracev((stderr, "inflate: codes new\n"));
74 }
75 return c;
76 }
77
78
79 int inflate_codes(s, z, r)
80 struct inflate_blocks_state *s;
81 z_stream *z;
82 int r;
83 {
84 uInt j; /* temporary storage */
85 inflate_huft *t; /* temporary pointer */
86 int e; /* extra bits or operation */
87 uLong b; /* bit buffer */
88 uInt k; /* bits in bit buffer */
89 Byte *p; /* input data pointer */
90 uInt n; /* bytes available there */
91 Byte *q; /* output window write pointer */
92 uInt m; /* bytes to end of window or read pointer */
93 Byte *f; /* pointer to copy strings from */
94 struct inflate_codes_state *c = s->sub.codes; /* codes state */
95
96 /* copy input/output information to locals (UPDATE macro restores) */
97 LOAD
98
99 /* process input and output based on current state */
100 while (1) switch (c->mode)
101 { /* waiting for "i:"=input, "o:"=output, "x:"=nothing */
102 case START: /* x: set up for LEN */
103 #ifndef SLOW
104 if (m >= 258 && n >= 10)
105 {
106 UPDATE
107 r = inflate_fast(c->lbits, c->dbits, c->ltree, c->dtree, s, z);
108 LOAD
109 if (r != Z_OK)
110 {
111 c->mode = r == Z_STREAM_END ? WASH : BADCODE;
112 break;
113 }
114 }
115 #endif /* !SLOW */
116 c->sub.code.need = c->lbits;
117 c->sub.code.tree = c->ltree;
118 c->mode = LEN;
119 case LEN: /* i: get length/literal/eob next */
120 j = c->sub.code.need;
121 NEEDBITS(j)
122 t = c->sub.code.tree + ((uInt)b & inflate_mask[j]);
123 DUMPBITS(t->bits)
124 if ((e = (int)(t->exop)) < 0)
125 {
126 if (e == -128) /* invalid code */
127 {
128 c->mode = BADCODE;
129 z->msg = "invalid literal/length code";
130 r = Z_DATA_ERROR;
131 LEAVE
132 }
133 e = -e;
134 if (e & 64) /* end of block */
135 {
136 Tracevv((stderr, "inflate: end of block\n"));
137 c->mode = WASH;
138 break;
139 }
140 c->sub.code.need = e;
141 c->sub.code.tree = t->next;
142 break;
143 }
144 if (e & 16) /* literal */
145 {
146 c->sub.lit = t->base;
147 Tracevv((stderr, t->base >= 0x20 && t->base < 0x7f ?
148 "inflate: literal '%c'\n" :
149 "inflate: literal 0x%02x\n", t->base));
150 c->mode = LIT;
151 break;
152 }
153 c->sub.copy.get = e;
154 c->len = t->base;
155 c->mode = LENEXT;
156 case LENEXT: /* i: getting length extra (have base) */
157 j = c->sub.copy.get;
158 NEEDBITS(j)
159 c->len += (uInt)b & inflate_mask[j];
160 DUMPBITS(j)
161 c->sub.code.need = c->dbits;
162 c->sub.code.tree = c->dtree;
163 Tracevv((stderr, "inflate: length %u\n", c->len));
164 c->mode = DIST;
165 case DIST: /* i: get distance next */
166 j = c->sub.code.need;
167 NEEDBITS(j)
168 t = c->sub.code.tree + ((uInt)b & inflate_mask[j]);
169 DUMPBITS(t->bits)
170 if ((e = (int)(t->exop)) < 0)
171 {
172 if (e == -128)
173 {
174 c->mode = BADCODE;
175 z->msg = "invalid distance code";
176 r = Z_DATA_ERROR;
177 LEAVE
178 }
179 c->sub.code.need = -e;
180 c->sub.code.tree = t->next;
181 break;
182 }
183 c->sub.copy.dist = t->base;
184 c->sub.copy.get = e;
185 c->mode = DISTEXT;
186 case DISTEXT: /* i: getting distance extra */
187 j = c->sub.copy.get;
188 NEEDBITS(j)
189 c->sub.copy.dist += (uInt)b & inflate_mask[j];
190 DUMPBITS(j)
191 Tracevv((stderr, "inflate: distance %u\n", c->sub.copy.dist));
192 c->mode = COPY;
193 case COPY: /* o: copying bytes in window, waiting for space */
194 f = (uInt)(q - s->window) < c->sub.copy.dist ?
195 s->end - (c->sub.copy.dist - (q - s->window)) :
196 q - c->sub.copy.dist;
197 while (c->len)
198 {
199 NEEDOUT
200 OUTBYTE(*f++)
201 if (f == s->end)
202 f = s->window;
203 c->len--;
204 }
205 c->mode = START;
206 break;
207 case LIT: /* o: got literal, waiting for output space */
208 NEEDOUT
209 OUTBYTE(c->sub.lit)
210 c->mode = START;
211 break;
212 case WASH: /* o: got eob, possibly more output */
213 FLUSH
214 if (s->read != s->write)
215 LEAVE
216 c->mode = END;
217 case END:
218 r = Z_STREAM_END;
219 LEAVE
220 case BADCODE: /* x: got error */
221 r = Z_DATA_ERROR;
222 LEAVE
223 default:
224 r = Z_STREAM_ERROR;
225 LEAVE
226 }
227 }
228
229
230 void inflate_codes_free(c, z)
231 struct inflate_codes_state *c;
232 z_stream *z;
233 {
234 inflate_trees_free(c->dtree, z);
235 inflate_trees_free(c->ltree, z);
236 ZFREE(z, c);
237 Tracev((stderr, "inflate: codes free\n"));
238 }