|
1 /* inffast.c -- process literals and length/distance pairs fast |
|
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 struct inflate_codes_state {int dummy;}; /* for buggy compilers */ |
|
14 |
|
15 /* simplify the use of the inflate_huft type with some defines */ |
|
16 #define exop word.what.Exop |
|
17 #define bits word.what.Bits |
|
18 |
|
19 /* macros for bit input with no checking and for returning unused bytes */ |
|
20 #define GRABBITS(j) {while(k<(j)){b|=((uLong)NEXTBYTE)<<k;k+=8;}} |
|
21 #define UNGRAB {c=z->avail_in-n;c=(k>>3)<c?k>>3:c;n+=c;p-=c;k-=c<<3;} |
|
22 |
|
23 /* Called with number of bytes left to write in window at least 258 |
|
24 (the maximum string length) and number of input bytes available |
|
25 at least ten. The ten bytes are six bytes for the longest length/ |
|
26 distance pair plus four bytes for overloading the bit buffer. */ |
|
27 |
|
28 int inflate_fast( |
|
29 uInt bl, uInt bd, |
|
30 const inflate_huft *tl, |
|
31 const inflate_huft *td, /* need separate declaration for Borland C++ */ |
|
32 inflate_blocks_statef *s, |
|
33 z_streamp z) |
|
34 { |
|
35 const inflate_huft *t; /* temporary pointer */ |
|
36 uInt e; /* extra bits or operation */ |
|
37 uLong b; /* bit buffer */ |
|
38 uInt k; /* bits in bit buffer */ |
|
39 Bytef *p; /* input data pointer */ |
|
40 uInt n; /* bytes available there */ |
|
41 Bytef *q; /* output window write pointer */ |
|
42 uInt m; /* bytes to end of window or read pointer */ |
|
43 uInt ml; /* mask for literal/length tree */ |
|
44 uInt md; /* mask for distance tree */ |
|
45 uInt c; /* bytes to copy */ |
|
46 uInt d; /* distance back to copy from */ |
|
47 Bytef *r; /* copy source pointer */ |
|
48 int alwaysTrue = 1; /* Added by Markr Symbian 9/11/99 to get rid of warnings */ |
|
49 /* load input, output, bit values */ |
|
50 LOAD |
|
51 |
|
52 /* initialize masks */ |
|
53 ml = inflate_mask[bl]; |
|
54 md = inflate_mask[bd]; |
|
55 |
|
56 /* do until not enough input or output space for fast loop */ |
|
57 do { /* assume called with m >= 258 && n >= 10 */ |
|
58 /* get literal/length code */ |
|
59 GRABBITS(20) /* max bits for literal/length code */ |
|
60 if ((e = (t = tl + ((uInt)b & ml))->exop) == 0) |
|
61 { |
|
62 DUMPBITS(t->bits) |
|
63 Tracevv((stderr, t->base >= 0x20 && t->base < 0x7f ? |
|
64 "inflate: * literal '%c'\n" : |
|
65 "inflate: * literal 0x%02x\n", t->base)); |
|
66 *q++ = (Byte)t->base; |
|
67 m--; |
|
68 continue; |
|
69 } |
|
70 do { |
|
71 DUMPBITS(t->bits) |
|
72 if (e & 16) |
|
73 { |
|
74 /* get extra bits for length */ |
|
75 e &= 15; |
|
76 c = t->base + ((uInt)b & inflate_mask[e]); |
|
77 DUMPBITS(e) |
|
78 Tracevv((stderr, "inflate: * length %u\n", c)); |
|
79 |
|
80 /* decode distance base of block to copy */ |
|
81 GRABBITS(15); /* max bits for distance code */ |
|
82 e = (t = td + ((uInt)b & md))->exop; |
|
83 do { |
|
84 DUMPBITS(t->bits) |
|
85 if (e & 16) |
|
86 { |
|
87 /* get extra bits to add to distance base */ |
|
88 e &= 15; |
|
89 GRABBITS(e) /* get extra bits (up to 13) */ |
|
90 d = t->base + ((uInt)b & inflate_mask[e]); |
|
91 DUMPBITS(e) |
|
92 Tracevv((stderr, "inflate: * distance %u\n", d)); |
|
93 |
|
94 /* do the copy */ |
|
95 m -= c; |
|
96 r = q - d; |
|
97 if (r < s->window) /* wrap if needed */ |
|
98 { |
|
99 do { |
|
100 r += s->end - s->window; /* force pointer in window */ |
|
101 } while (r < s->window); /* covers invalid distances */ |
|
102 e = s->end - r; |
|
103 if (c > e) |
|
104 { |
|
105 c -= e; /* wrapped copy */ |
|
106 do { |
|
107 *q++ = *r++; |
|
108 } while (--e); |
|
109 r = s->window; |
|
110 do { |
|
111 *q++ = *r++; |
|
112 } while (--c); |
|
113 } |
|
114 else /* normal copy */ |
|
115 { |
|
116 *q++ = *r++; c--; |
|
117 *q++ = *r++; c--; |
|
118 do { |
|
119 *q++ = *r++; |
|
120 } while (--c); |
|
121 } |
|
122 } |
|
123 else /* normal copy */ |
|
124 { |
|
125 *q++ = *r++; c--; |
|
126 *q++ = *r++; c--; |
|
127 do { |
|
128 *q++ = *r++; |
|
129 } while (--c); |
|
130 } |
|
131 break; |
|
132 } |
|
133 else if ((e & 64) == 0) |
|
134 { |
|
135 t += t->base; |
|
136 e = (t += ((uInt)b & inflate_mask[e]))->exop; |
|
137 } |
|
138 else |
|
139 { |
|
140 z->msg = (char*)"invalid distance code"; |
|
141 UNGRAB |
|
142 UPDATE |
|
143 return Z_DATA_ERROR; |
|
144 } |
|
145 } while (alwaysTrue); // Changed by Markr to alleviate warning |
|
146 break; |
|
147 } |
|
148 if ((e & 64) == 0) |
|
149 { |
|
150 t += t->base; |
|
151 if ((e = (t += ((uInt)b & inflate_mask[e]))->exop) == 0) |
|
152 { |
|
153 DUMPBITS(t->bits) |
|
154 Tracevv((stderr, t->base >= 0x20 && t->base < 0x7f ? |
|
155 "inflate: * literal '%c'\n" : |
|
156 "inflate: * literal 0x%02x\n", t->base)); |
|
157 *q++ = (Byte)t->base; |
|
158 m--; |
|
159 break; |
|
160 } |
|
161 } |
|
162 else if (e & 32) |
|
163 { |
|
164 Tracevv((stderr, "inflate: * end of block\n")); |
|
165 UNGRAB |
|
166 UPDATE |
|
167 return Z_STREAM_END; |
|
168 } |
|
169 else |
|
170 { |
|
171 z->msg = (char*)"invalid literal/length code"; |
|
172 UNGRAB |
|
173 UPDATE |
|
174 return Z_DATA_ERROR; |
|
175 } |
|
176 } while (alwaysTrue); // Changed by Markr to alleviate warning |
|
177 } while (m >= 258 && n >= 10); |
|
178 |
|
179 /* not enough input or output--restore pointers and return */ |
|
180 UNGRAB |
|
181 UPDATE |
|
182 return Z_OK; |
|
183 } |