]>
Commit | Line | Data |
---|---|---|
1da177e4 LT |
1 | /* zutil.h -- internal interface and configuration of the compression library |
2 | * Copyright (C) 1995-1998 Jean-loup Gailly. | |
3 | * For conditions of distribution and use, see copyright notice in zlib.h | |
4 | */ | |
5 | ||
6 | /* WARNING: this file should *not* be used by applications. It is | |
7 | part of the implementation of the compression library and is | |
8 | subject to change. Applications should only use zlib.h. | |
9 | */ | |
10 | ||
11 | /* @(#) $Id: zutil.h,v 1.1 2000/01/01 03:32:23 davem Exp $ */ | |
12 | ||
13 | #ifndef _Z_UTIL_H | |
14 | #define _Z_UTIL_H | |
15 | ||
16 | #include <linux/zlib.h> | |
17 | #include <linux/string.h> | |
18 | #include <linux/errno.h> | |
19 | #include <linux/kernel.h> | |
20 | ||
21 | typedef unsigned char uch; | |
22 | typedef unsigned short ush; | |
23 | typedef unsigned long ulg; | |
24 | ||
25 | /* common constants */ | |
26 | ||
27 | #ifndef DEF_WBITS | |
28 | # define DEF_WBITS MAX_WBITS | |
29 | #endif | |
30 | /* default windowBits for decompression. MAX_WBITS is for compression only */ | |
31 | ||
32 | #if MAX_MEM_LEVEL >= 8 | |
33 | # define DEF_MEM_LEVEL 8 | |
34 | #else | |
35 | # define DEF_MEM_LEVEL MAX_MEM_LEVEL | |
36 | #endif | |
37 | /* default memLevel */ | |
38 | ||
39 | #define STORED_BLOCK 0 | |
40 | #define STATIC_TREES 1 | |
41 | #define DYN_TREES 2 | |
42 | /* The three kinds of block type */ | |
43 | ||
44 | #define MIN_MATCH 3 | |
45 | #define MAX_MATCH 258 | |
46 | /* The minimum and maximum match lengths */ | |
47 | ||
48 | #define PRESET_DICT 0x20 /* preset dictionary flag in zlib header */ | |
49 | ||
50 | /* target dependencies */ | |
51 | ||
52 | /* Common defaults */ | |
53 | ||
54 | #ifndef OS_CODE | |
55 | # define OS_CODE 0x03 /* assume Unix */ | |
56 | #endif | |
57 | ||
58 | /* functions */ | |
59 | ||
60 | typedef uLong (*check_func) (uLong check, const Byte *buf, | |
61 | uInt len); | |
62 | ||
63 | ||
64 | /* checksum functions */ | |
65 | ||
66 | #define BASE 65521L /* largest prime smaller than 65536 */ | |
67 | #define NMAX 5552 | |
68 | /* NMAX is the largest n such that 255n(n+1)/2 + (n+1)(BASE-1) <= 2^32-1 */ | |
69 | ||
70 | #define DO1(buf,i) {s1 += buf[i]; s2 += s1;} | |
71 | #define DO2(buf,i) DO1(buf,i); DO1(buf,i+1); | |
72 | #define DO4(buf,i) DO2(buf,i); DO2(buf,i+2); | |
73 | #define DO8(buf,i) DO4(buf,i); DO4(buf,i+4); | |
74 | #define DO16(buf) DO8(buf,0); DO8(buf,8); | |
75 | ||
76 | /* ========================================================================= */ | |
77 | /* | |
78 | Update a running Adler-32 checksum with the bytes buf[0..len-1] and | |
79 | return the updated checksum. If buf is NULL, this function returns | |
80 | the required initial value for the checksum. | |
81 | An Adler-32 checksum is almost as reliable as a CRC32 but can be computed | |
82 | much faster. Usage example: | |
83 | ||
84 | uLong adler = adler32(0L, NULL, 0); | |
85 | ||
86 | while (read_buffer(buffer, length) != EOF) { | |
87 | adler = adler32(adler, buffer, length); | |
88 | } | |
89 | if (adler != original_adler) error(); | |
90 | */ | |
91 | static inline uLong zlib_adler32(uLong adler, | |
92 | const Byte *buf, | |
93 | uInt len) | |
94 | { | |
95 | unsigned long s1 = adler & 0xffff; | |
96 | unsigned long s2 = (adler >> 16) & 0xffff; | |
97 | int k; | |
98 | ||
99 | if (buf == NULL) return 1L; | |
100 | ||
101 | while (len > 0) { | |
102 | k = len < NMAX ? len : NMAX; | |
103 | len -= k; | |
104 | while (k >= 16) { | |
105 | DO16(buf); | |
106 | buf += 16; | |
107 | k -= 16; | |
108 | } | |
109 | if (k != 0) do { | |
110 | s1 += *buf++; | |
111 | s2 += s1; | |
112 | } while (--k); | |
113 | s1 %= BASE; | |
114 | s2 %= BASE; | |
115 | } | |
116 | return (s2 << 16) | s1; | |
117 | } | |
118 | ||
119 | #endif /* _Z_UTIL_H */ |