1*4882a593Smuzhiyun /* zutil.h -- internal interface and configuration of the compression library
2*4882a593Smuzhiyun * Copyright (C) 1995-1998 Jean-loup Gailly.
3*4882a593Smuzhiyun * For conditions of distribution and use, see copyright notice in zlib.h
4*4882a593Smuzhiyun */
5*4882a593Smuzhiyun
6*4882a593Smuzhiyun /* WARNING: this file should *not* be used by applications. It is
7*4882a593Smuzhiyun part of the implementation of the compression library and is
8*4882a593Smuzhiyun subject to change. Applications should only use zlib.h.
9*4882a593Smuzhiyun */
10*4882a593Smuzhiyun
11*4882a593Smuzhiyun /* @(#) $Id: zutil.h,v 1.1 2000/01/01 03:32:23 davem Exp $ */
12*4882a593Smuzhiyun
13*4882a593Smuzhiyun #ifndef _Z_UTIL_H
14*4882a593Smuzhiyun #define _Z_UTIL_H
15*4882a593Smuzhiyun
16*4882a593Smuzhiyun #include <linux/zlib.h>
17*4882a593Smuzhiyun #include <linux/string.h>
18*4882a593Smuzhiyun #include <linux/kernel.h>
19*4882a593Smuzhiyun
20*4882a593Smuzhiyun typedef unsigned char uch;
21*4882a593Smuzhiyun typedef unsigned short ush;
22*4882a593Smuzhiyun typedef unsigned long ulg;
23*4882a593Smuzhiyun
24*4882a593Smuzhiyun /* common constants */
25*4882a593Smuzhiyun
26*4882a593Smuzhiyun #define STORED_BLOCK 0
27*4882a593Smuzhiyun #define STATIC_TREES 1
28*4882a593Smuzhiyun #define DYN_TREES 2
29*4882a593Smuzhiyun /* The three kinds of block type */
30*4882a593Smuzhiyun
31*4882a593Smuzhiyun #define MIN_MATCH 3
32*4882a593Smuzhiyun #define MAX_MATCH 258
33*4882a593Smuzhiyun /* The minimum and maximum match lengths */
34*4882a593Smuzhiyun
35*4882a593Smuzhiyun #define PRESET_DICT 0x20 /* preset dictionary flag in zlib header */
36*4882a593Smuzhiyun
37*4882a593Smuzhiyun /* target dependencies */
38*4882a593Smuzhiyun
39*4882a593Smuzhiyun /* Common defaults */
40*4882a593Smuzhiyun
41*4882a593Smuzhiyun #ifndef OS_CODE
42*4882a593Smuzhiyun # define OS_CODE 0x03 /* assume Unix */
43*4882a593Smuzhiyun #endif
44*4882a593Smuzhiyun
45*4882a593Smuzhiyun /* functions */
46*4882a593Smuzhiyun
47*4882a593Smuzhiyun typedef uLong (*check_func) (uLong check, const Byte *buf,
48*4882a593Smuzhiyun uInt len);
49*4882a593Smuzhiyun
50*4882a593Smuzhiyun
51*4882a593Smuzhiyun /* checksum functions */
52*4882a593Smuzhiyun
53*4882a593Smuzhiyun #define BASE 65521L /* largest prime smaller than 65536 */
54*4882a593Smuzhiyun #define NMAX 5552
55*4882a593Smuzhiyun /* NMAX is the largest n such that 255n(n+1)/2 + (n+1)(BASE-1) <= 2^32-1 */
56*4882a593Smuzhiyun
57*4882a593Smuzhiyun #define DO1(buf,i) {s1 += buf[i]; s2 += s1;}
58*4882a593Smuzhiyun #define DO2(buf,i) DO1(buf,i); DO1(buf,i+1);
59*4882a593Smuzhiyun #define DO4(buf,i) DO2(buf,i); DO2(buf,i+2);
60*4882a593Smuzhiyun #define DO8(buf,i) DO4(buf,i); DO4(buf,i+4);
61*4882a593Smuzhiyun #define DO16(buf) DO8(buf,0); DO8(buf,8);
62*4882a593Smuzhiyun
63*4882a593Smuzhiyun /* ========================================================================= */
64*4882a593Smuzhiyun /*
65*4882a593Smuzhiyun Update a running Adler-32 checksum with the bytes buf[0..len-1] and
66*4882a593Smuzhiyun return the updated checksum. If buf is NULL, this function returns
67*4882a593Smuzhiyun the required initial value for the checksum.
68*4882a593Smuzhiyun An Adler-32 checksum is almost as reliable as a CRC32 but can be computed
69*4882a593Smuzhiyun much faster. Usage example:
70*4882a593Smuzhiyun
71*4882a593Smuzhiyun uLong adler = zlib_adler32(0L, NULL, 0);
72*4882a593Smuzhiyun
73*4882a593Smuzhiyun while (read_buffer(buffer, length) != EOF) {
74*4882a593Smuzhiyun adler = zlib_adler32(adler, buffer, length);
75*4882a593Smuzhiyun }
76*4882a593Smuzhiyun if (adler != original_adler) error();
77*4882a593Smuzhiyun */
zlib_adler32(uLong adler,const Byte * buf,uInt len)78*4882a593Smuzhiyun static inline uLong zlib_adler32(uLong adler,
79*4882a593Smuzhiyun const Byte *buf,
80*4882a593Smuzhiyun uInt len)
81*4882a593Smuzhiyun {
82*4882a593Smuzhiyun unsigned long s1 = adler & 0xffff;
83*4882a593Smuzhiyun unsigned long s2 = (adler >> 16) & 0xffff;
84*4882a593Smuzhiyun int k;
85*4882a593Smuzhiyun
86*4882a593Smuzhiyun if (buf == NULL) return 1L;
87*4882a593Smuzhiyun
88*4882a593Smuzhiyun while (len > 0) {
89*4882a593Smuzhiyun k = len < NMAX ? len : NMAX;
90*4882a593Smuzhiyun len -= k;
91*4882a593Smuzhiyun while (k >= 16) {
92*4882a593Smuzhiyun DO16(buf);
93*4882a593Smuzhiyun buf += 16;
94*4882a593Smuzhiyun k -= 16;
95*4882a593Smuzhiyun }
96*4882a593Smuzhiyun if (k != 0) do {
97*4882a593Smuzhiyun s1 += *buf++;
98*4882a593Smuzhiyun s2 += s1;
99*4882a593Smuzhiyun } while (--k);
100*4882a593Smuzhiyun s1 %= BASE;
101*4882a593Smuzhiyun s2 %= BASE;
102*4882a593Smuzhiyun }
103*4882a593Smuzhiyun return (s2 << 16) | s1;
104*4882a593Smuzhiyun }
105*4882a593Smuzhiyun
106*4882a593Smuzhiyun #endif /* _Z_UTIL_H */
107