Linux kernel mirror (for testing)
git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
tjh.dev
kernel
os
linux
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/kernel.h>
19
20typedef unsigned char uch;
21typedef unsigned short ush;
22typedef unsigned long ulg;
23
24 /* common constants */
25
26#ifndef DEF_WBITS
27# define DEF_WBITS MAX_WBITS
28#endif
29/* default windowBits for decompression. MAX_WBITS is for compression only */
30
31#if MAX_MEM_LEVEL >= 8
32# define DEF_MEM_LEVEL 8
33#else
34# define DEF_MEM_LEVEL MAX_MEM_LEVEL
35#endif
36/* default memLevel */
37
38#define STORED_BLOCK 0
39#define STATIC_TREES 1
40#define DYN_TREES 2
41/* The three kinds of block type */
42
43#define MIN_MATCH 3
44#define MAX_MATCH 258
45/* The minimum and maximum match lengths */
46
47#define PRESET_DICT 0x20 /* preset dictionary flag in zlib header */
48
49 /* target dependencies */
50
51 /* Common defaults */
52
53#ifndef OS_CODE
54# define OS_CODE 0x03 /* assume Unix */
55#endif
56
57 /* functions */
58
59typedef uLong (*check_func) (uLong check, const Byte *buf,
60 uInt len);
61
62
63 /* checksum functions */
64
65#define BASE 65521L /* largest prime smaller than 65536 */
66#define NMAX 5552
67/* NMAX is the largest n such that 255n(n+1)/2 + (n+1)(BASE-1) <= 2^32-1 */
68
69#define DO1(buf,i) {s1 += buf[i]; s2 += s1;}
70#define DO2(buf,i) DO1(buf,i); DO1(buf,i+1);
71#define DO4(buf,i) DO2(buf,i); DO2(buf,i+2);
72#define DO8(buf,i) DO4(buf,i); DO4(buf,i+4);
73#define DO16(buf) DO8(buf,0); DO8(buf,8);
74
75/* ========================================================================= */
76/*
77 Update a running Adler-32 checksum with the bytes buf[0..len-1] and
78 return the updated checksum. If buf is NULL, this function returns
79 the required initial value for the checksum.
80 An Adler-32 checksum is almost as reliable as a CRC32 but can be computed
81 much faster. Usage example:
82
83 uLong adler = adler32(0L, NULL, 0);
84
85 while (read_buffer(buffer, length) != EOF) {
86 adler = adler32(adler, buffer, length);
87 }
88 if (adler != original_adler) error();
89*/
90static inline uLong zlib_adler32(uLong adler,
91 const Byte *buf,
92 uInt len)
93{
94 unsigned long s1 = adler & 0xffff;
95 unsigned long s2 = (adler >> 16) & 0xffff;
96 int k;
97
98 if (buf == NULL) return 1L;
99
100 while (len > 0) {
101 k = len < NMAX ? len : NMAX;
102 len -= k;
103 while (k >= 16) {
104 DO16(buf);
105 buf += 16;
106 k -= 16;
107 }
108 if (k != 0) do {
109 s1 += *buf++;
110 s2 += s1;
111 } while (--k);
112 s1 %= BASE;
113 s2 %= BASE;
114 }
115 return (s2 << 16) | s1;
116}
117
118#endif /* _Z_UTIL_H */