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 <linux/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 inflate_codes_statef *zlib_inflate_codes_new(
18 uInt bl,
19 uInt bd,
20 inflate_huft *tl,
21 inflate_huft *td, /* need separate declaration for Borland C++ */
22 z_streamp z
23 )
24 {
25 inflate_codes_statef *c;
26
27 c = &WS(z)->working_state;
28 {
29 c->mode = START;
30 c->lbits = (Byte)bl;
31 c->dbits = (Byte)bd;
32 c->ltree = tl;
33 c->dtree = td;
34 }
35 return c;
36 }
37
38
39 int zlib_inflate_codes(
40 inflate_blocks_statef *s,
41 z_streamp z,
42 int r
43 )
44 {
45 uInt j; /* temporary storage */
46 inflate_huft *t; /* temporary pointer */
47 uInt e; /* extra bits or operation */
48 uLong b; /* bit buffer */
49 uInt k; /* bits in bit buffer */
50 Byte *p; /* input data pointer */
51 uInt n; /* bytes available there */
52 Byte *q; /* output window write pointer */
53 uInt m; /* bytes to end of window or read pointer */
54 Byte *f; /* pointer to copy strings from */
55 inflate_codes_statef *c = s->sub.decode.codes; /* codes state */
56
57 /* copy input/output information to locals (UPDATE macro restores) */
58 LOAD
59
60 /* process input and output based on current state */
61 while (1) switch (c->mode)
62 { /* waiting for "i:"=input, "o:"=output, "x:"=nothing */
63 case START: /* x: set up for LEN */
64 #ifndef SLOW
65 if (m >= 258 && n >= 10)
66 {
67 UPDATE
68 r = zlib_inflate_fast(c->lbits, c->dbits, c->ltree, c->dtree, s, z);
69 LOAD
70 if (r != Z_OK)
71 {
72 c->mode = r == Z_STREAM_END ? WASH : BADCODE;
73 break;
74 }
75 }
76 #endif /* !SLOW */
77 c->sub.code.need = c->lbits;
78 c->sub.code.tree = c->ltree;
79 c->mode = LEN;
80 case LEN: /* i: get length/literal/eob next */
81 j = c->sub.code.need;
82 NEEDBITS(j)
83 t = c->sub.code.tree + ((uInt)b & zlib_inflate_mask[j]);
84 DUMPBITS(t->bits)
85 e = (uInt)(t->exop);
86 if (e == 0) /* literal */
87 {
88 c->sub.lit = t->base;
89 c->mode = LIT;
90 break;
91 }
92 if (e & 16) /* length */
93 {
94 c->sub.copy.get = e & 15;
95 c->len = t->base;
96 c->mode = LENEXT;
97 break;
98 }
99 if ((e & 64) == 0) /* next table */
100 {
101 c->sub.code.need = e;
102 c->sub.code.tree = t + t->base;
103 break;
104 }
105 if (e & 32) /* end of block */
106 {
107 c->mode = WASH;
108 break;
109 }
110 c->mode = BADCODE; /* invalid code */
111 z->msg = (char*)"invalid literal/length code";
112 r = Z_DATA_ERROR;
113 LEAVE
114 case LENEXT: /* i: getting length extra (have base) */
115 j = c->sub.copy.get;
116 NEEDBITS(j)
117 c->len += (uInt)b & zlib_inflate_mask[j];
118 DUMPBITS(j)
119 c->sub.code.need = c->dbits;
120 c->sub.code.tree = c->dtree;
121 c->mode = DIST;
122 case DIST: /* i: get distance next */
123 j = c->sub.code.need;
124 NEEDBITS(j)
125 t = c->sub.code.tree + ((uInt)b & zlib_inflate_mask[j]);
126 DUMPBITS(t->bits)
127 e = (uInt)(t->exop);
128 if (e & 16) /* distance */
129 {
130 c->sub.copy.get = e & 15;
131 c->sub.copy.dist = t->base;
132 c->mode = DISTEXT;
133 break;
134 }
135 if ((e & 64) == 0) /* next table */
136 {
137 c->sub.code.need = e;
138 c->sub.code.tree = t + t->base;
139 break;
140 }
141 c->mode = BADCODE; /* invalid code */
142 z->msg = (char*)"invalid distance code";
143 r = Z_DATA_ERROR;
144 LEAVE
145 case DISTEXT: /* i: getting distance extra */
146 j = c->sub.copy.get;
147 NEEDBITS(j)
148 c->sub.copy.dist += (uInt)b & zlib_inflate_mask[j];
149 DUMPBITS(j)
150 c->mode = COPY;
151 case COPY: /* o: copying bytes in window, waiting for space */
152 f = q - c->sub.copy.dist;
153 while (f < s->window) /* modulo window size-"while" instead */
154 f += s->end - s->window; /* of "if" handles invalid distances */
155 while (c->len)
156 {
157 NEEDOUT
158 OUTBYTE(*f++)
159 if (f == s->end)
160 f = s->window;
161 c->len--;
162 }
163 c->mode = START;
164 break;
165 case LIT: /* o: got literal, waiting for output space */
166 NEEDOUT
167 OUTBYTE(c->sub.lit)
168 c->mode = START;
169 break;
170 case WASH: /* o: got eob, possibly more output */
171 if (k > 7) /* return unused byte, if any */
172 {
173 k -= 8;
174 n++;
175 p--; /* can always return one */
176 }
177 FLUSH
178 if (s->read != s->write)
179 LEAVE
180 c->mode = END;
181 case END:
182 r = Z_STREAM_END;
183 LEAVE
184 case BADCODE: /* x: got error */
185 r = Z_DATA_ERROR;
186 LEAVE
187 default:
188 r = Z_STREAM_ERROR;
189 LEAVE
190 }
191 #ifdef NEED_DUMMY_RETURN
192 return Z_STREAM_ERROR; /* Some dumb compilers complain without this */
193 #endif
194 }
195
196
197 void zlib_inflate_codes_free(
198 inflate_codes_statef *c,
199 z_streamp z
200 )
201 {
202 }
203
|
This page was automatically generated by the
LXR engine.
|