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author | Mark Adler <madler@alumni.caltech.edu> | 2011-09-09 22:52:17 -0700 |
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committer | Mark Adler <madler@alumni.caltech.edu> | 2011-09-09 22:52:17 -0700 |
commit | 913afb9174bb474104049906c1382dec81826424 (patch) | |
tree | 46bb8ca746088f81382b4f33970b9d43c33d9ba3 /inffast.c | |
parent | bcf78a20978d76f64b7cd46d1a4d7a79a578c77b (diff) | |
download | zlib-913afb9174bb474104049906c1382dec81826424.tar.gz zlib-913afb9174bb474104049906c1382dec81826424.tar.bz2 zlib-913afb9174bb474104049906c1382dec81826424.zip |
zlib 0.79v0.79
Diffstat (limited to 'inffast.c')
-rw-r--r-- | inffast.c | 148 |
1 files changed, 148 insertions, 0 deletions
diff --git a/inffast.c b/inffast.c new file mode 100644 index 0000000..8c3e4ce --- /dev/null +++ b/inffast.c | |||
@@ -0,0 +1,148 @@ | |||
1 | /* inffast.c -- process literals and length/distance pairs fast | ||
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 | |||
11 | /* simplify the use of the inflate_huft type with some defines */ | ||
12 | #define base more.Base | ||
13 | #define next more.Next | ||
14 | #define exop word.what.Exop | ||
15 | #define bits word.what.Bits | ||
16 | |||
17 | /* macros for bit input with no checking and for returning unused bytes */ | ||
18 | #ifdef DEBUG | ||
19 | # undef NEXTBYTE | ||
20 | # define NEXTBYTE (n--?0:fprintf(stderr,"inffast underrun\n"),*p++) | ||
21 | #endif | ||
22 | #define GRABBITS(j) {while(k<(j)){b|=((uLong)NEXTBYTE)<<k;k+=8;}} | ||
23 | #define UNGRAB {n+=(c=k>>3);p-=c;k&=7;} | ||
24 | |||
25 | /* Called with number of bytes left to write in window at least 258 | ||
26 | (the maximum string length) and number of input bytes available | ||
27 | at least ten. The ten bytes are six bytes for the longest length/ | ||
28 | distance pair plus four bytes for overloading the bit buffer. */ | ||
29 | |||
30 | int inflate_fast(bl, bd, tl, td, s, z) | ||
31 | uInt bl, bd; | ||
32 | inflate_huft *tl, *td; | ||
33 | struct inflate_blocks_state *s; | ||
34 | z_stream *z; | ||
35 | { | ||
36 | inflate_huft *t; /* temporary pointer */ | ||
37 | int e; /* extra bits or operation */ | ||
38 | uLong b; /* bit buffer */ | ||
39 | uInt k; /* bits in bit buffer */ | ||
40 | Byte *p; /* input data pointer */ | ||
41 | uInt n; /* bytes available there */ | ||
42 | Byte *q; /* output window write pointer */ | ||
43 | uInt m; /* bytes to end of window or read pointer */ | ||
44 | uInt ml; /* mask for literal/length tree */ | ||
45 | uInt md; /* mask for distance tree */ | ||
46 | uInt c; /* bytes to copy */ | ||
47 | uInt d; /* distance back to copy from */ | ||
48 | Byte *r; /* copy source pointer */ | ||
49 | |||
50 | /* load input, output, bit values */ | ||
51 | LOAD | ||
52 | |||
53 | /* initialize masks in registers */ | ||
54 | ml = inflate_mask[bl]; | ||
55 | md = inflate_mask[bd]; | ||
56 | |||
57 | /* do until not enough input or output space for fast loop */ | ||
58 | do { /* assume called with m >= 258 && n >= 10 */ | ||
59 | /* get literal/length code */ | ||
60 | GRABBITS(20) /* max bits for literal/length code */ | ||
61 | if ((e = (t = tl + ((uInt)b & ml))->exop) < 0) | ||
62 | do { | ||
63 | if (e == -128) | ||
64 | { | ||
65 | z->msg = "invalid literal/length code"; | ||
66 | UNGRAB | ||
67 | UPDATE | ||
68 | return Z_DATA_ERROR; | ||
69 | } | ||
70 | DUMPBITS(t->bits) | ||
71 | e = -e; | ||
72 | if (e & 64) /* end of block */ | ||
73 | { | ||
74 | UNGRAB | ||
75 | UPDATE | ||
76 | return Z_STREAM_END; | ||
77 | } | ||
78 | } while ((e = (t = t->next + ((uInt)b & inflate_mask[e]))->exop) < 0); | ||
79 | DUMPBITS(t->bits) | ||
80 | |||
81 | /* process literal or length (end of block already trapped) */ | ||
82 | if (e & 16) /* then it's a literal */ | ||
83 | { | ||
84 | *q++ = (Byte)t->base; | ||
85 | m--; | ||
86 | } | ||
87 | else /* it's a length */ | ||
88 | { | ||
89 | /* get length of block to copy (already have extra bits) */ | ||
90 | c = t->base + ((uInt)b & inflate_mask[e]); | ||
91 | DUMPBITS(e); | ||
92 | |||
93 | /* decode distance base of block to copy */ | ||
94 | GRABBITS(15); /* max bits for distance code */ | ||
95 | if ((e = (t = td + ((uInt)b & md))->exop) < 0) | ||
96 | do { | ||
97 | if (e == -128) | ||
98 | { | ||
99 | z->msg = "invalid distance code"; | ||
100 | UNGRAB | ||
101 | UPDATE | ||
102 | return Z_DATA_ERROR; | ||
103 | } | ||
104 | DUMPBITS(t->bits) | ||
105 | e = -e; | ||
106 | } while ((e = (t = t->next + ((uInt)b & inflate_mask[e]))->exop) < 0); | ||
107 | DUMPBITS(t->bits) | ||
108 | |||
109 | /* get extra bits to add to distance base */ | ||
110 | GRABBITS(e) /* get extra bits (up to 13) */ | ||
111 | d = t->base + ((uInt)b & inflate_mask[e]); | ||
112 | DUMPBITS(e) | ||
113 | |||
114 | /* do the copy */ | ||
115 | m -= c; | ||
116 | if (q - s->window >= d) /* if offset before destination, */ | ||
117 | { /* just copy */ | ||
118 | r = q - d; | ||
119 | *q++ = *r++; c--; /* minimum count is three, */ | ||
120 | *q++ = *r++; c--; /* so unroll loop a little */ | ||
121 | do { | ||
122 | *q++ = *r++; | ||
123 | } while (--c); | ||
124 | } | ||
125 | else /* else offset after destination */ | ||
126 | { | ||
127 | e = d - (q - s->window); /* bytes from offset to end */ | ||
128 | r = s->end - e; /* pointer to offset */ | ||
129 | if (c > e) /* if source crosses, */ | ||
130 | { | ||
131 | c -= e; /* copy to end of window */ | ||
132 | do { | ||
133 | *q++ = *r++; | ||
134 | } while (--e); | ||
135 | r = s->window; /* copy rest from start of window */ | ||
136 | } | ||
137 | do { /* copy all or what's left */ | ||
138 | *q++ = *r++; | ||
139 | } while (--c); | ||
140 | } | ||
141 | } | ||
142 | } while (m >= 258 && n >= 10); | ||
143 | |||
144 | /* not enough input or output--restore pointers and return */ | ||
145 | UNGRAB | ||
146 | UPDATE | ||
147 | return Z_OK; | ||
148 | } | ||