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c801d85f 1/* inffast.c -- process literals and length/distance pairs fast
a4019ec2 2 * Copyright (C) 1995-2002 Mark Adler
e6ebb514 3 * For conditions of distribution and use, see copyright notice in zlib.h
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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
13struct 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
75bce3ad 28#if defined(__VISAGECPP__) /* Visualage can't handle this antiquated interface */
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29int inflate_fast(uInt bl, uInt bd, inflate_huft* tl, inflate_huft* td, inflate_blocks_statef* s, z_streamp z)
30#else
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31int inflate_fast(bl, bd, tl, td, s, z)
32uInt bl, bd;
33inflate_huft *tl;
34inflate_huft *td; /* need separate declaration for Borland C++ */
35inflate_blocks_statef *s;
36z_streamp z;
e6ebb514 37#endif
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38{
39 inflate_huft *t; /* temporary pointer */
40 uInt e; /* extra bits or operation */
41 uLong b; /* bit buffer */
42 uInt k; /* bits in bit buffer */
43 Bytef *p; /* input data pointer */
44 uInt n; /* bytes available there */
45 Bytef *q; /* output window write pointer */
46 uInt m; /* bytes to end of window or read pointer */
47 uInt ml; /* mask for literal/length tree */
48 uInt md; /* mask for distance tree */
49 uInt c; /* bytes to copy */
50 uInt d; /* distance back to copy from */
51 Bytef *r; /* copy source pointer */
52
53 /* load input, output, bit values */
54 LOAD
55
56 /* initialize masks */
57 ml = inflate_mask[bl];
58 md = inflate_mask[bd];
59
60 /* do until not enough input or output space for fast loop */
61 do { /* assume called with m >= 258 && n >= 10 */
62 /* get literal/length code */
63 GRABBITS(20) /* max bits for literal/length code */
64 if ((e = (t = tl + ((uInt)b & ml))->exop) == 0)
65 {
66 DUMPBITS(t->bits)
67 Tracevv((stderr, t->base >= 0x20 && t->base < 0x7f ?
68 "inflate: * literal '%c'\n" :
69 "inflate: * literal 0x%02x\n", t->base));
70 *q++ = (Byte)t->base;
71 m--;
72 continue;
73 }
74 do {
75 DUMPBITS(t->bits)
76 if (e & 16)
77 {
78 /* get extra bits for length */
79 e &= 15;
80 c = t->base + ((uInt)b & inflate_mask[e]);
81 DUMPBITS(e)
82 Tracevv((stderr, "inflate: * length %u\n", c));
83
84 /* decode distance base of block to copy */
85 GRABBITS(15); /* max bits for distance code */
86 e = (t = td + ((uInt)b & md))->exop;
87 do {
88 DUMPBITS(t->bits)
89 if (e & 16)
90 {
91 /* get extra bits to add to distance base */
92 e &= 15;
93 GRABBITS(e) /* get extra bits (up to 13) */
94 d = t->base + ((uInt)b & inflate_mask[e]);
95 DUMPBITS(e)
96 Tracevv((stderr, "inflate: * distance %u\n", d));
97
98 /* do the copy */
99 m -= c;
c801d85f 100 r = q - d;
a4019ec2 101 if (r < s->window) /* wrap if needed */
c801d85f 102 {
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103 do {
104 r += s->end - s->window; /* force pointer in window */
105 } while (r < s->window); /* covers invalid distances */
106 e = s->end - r;
107 if (c > e)
c801d85f 108 {
a4019ec2 109 c -= e; /* wrapped copy */
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110 do {
111 *q++ = *r++;
112 } while (--e);
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113 r = s->window;
114 do {
115 *q++ = *r++;
116 } while (--c);
117 }
118 else /* normal copy */
119 {
120 *q++ = *r++; c--;
121 *q++ = *r++; c--;
122 do {
123 *q++ = *r++;
124 } while (--c);
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125 }
126 }
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127 else /* normal copy */
128 {
129 *q++ = *r++; c--;
130 *q++ = *r++; c--;
131 do {
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132 *q++ = *r++;
133 } while (--c);
a4019ec2 134 }
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135 break;
136 }
137 else if ((e & 64) == 0)
138 {
139 t += t->base;
140 e = (t += ((uInt)b & inflate_mask[e]))->exop;
141 }
142 else
143 {
144 z->msg = (char*)"invalid distance code";
145 UNGRAB
146 UPDATE
147 return Z_DATA_ERROR;
148 }
149 } while (1);
150 break;
151 }
152 if ((e & 64) == 0)
153 {
154 t += t->base;
155 if ((e = (t += ((uInt)b & inflate_mask[e]))->exop) == 0)
156 {
157 DUMPBITS(t->bits)
158 Tracevv((stderr, t->base >= 0x20 && t->base < 0x7f ?
159 "inflate: * literal '%c'\n" :
160 "inflate: * literal 0x%02x\n", t->base));
161 *q++ = (Byte)t->base;
162 m--;
163 break;
164 }
165 }
166 else if (e & 32)
167 {
168 Tracevv((stderr, "inflate: * end of block\n"));
169 UNGRAB
170 UPDATE
171 return Z_STREAM_END;
172 }
173 else
174 {
175 z->msg = (char*)"invalid literal/length code";
176 UNGRAB
177 UPDATE
178 return Z_DATA_ERROR;
179 }
180 } while (1);
181 } while (m >= 258 && n >= 10);
182
183 /* not enough input or output--restore pointers and return */
184 UNGRAB
185 UPDATE
186 return Z_OK;
187}