projects / deliverable / linux.git / blame
| 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> | |
| 1da177e4 LT |
18 | #include <linux/kernel.h> |
| 19 | ||
| 20 | typedef unsigned char uch; | |
| 21 | typedef unsigned short ush; | |
| 22 | typedef unsigned long ulg; | |
| 23 | ||
| 24 | /* common constants */ | |
| 25 | ||
| 1da177e4 LT |
26 | #define STORED_BLOCK 0 |
| 27 | #define STATIC_TREES 1 | |
| 28 | #define DYN_TREES 2 | |
| 29 | /* The three kinds of block type */ | |
| 30 | ||
| 31 | #define MIN_MATCH 3 | |
| 32 | #define MAX_MATCH 258 | |
| 33 | /* The minimum and maximum match lengths */ | |
| 34 | ||
| 35 | #define PRESET_DICT 0x20 /* preset dictionary flag in zlib header */ | |
| 36 | ||
| 37 | /* target dependencies */ | |
| 38 | ||
| 39 | /* Common defaults */ | |
| 40 | ||
| 41 | #ifndef OS_CODE | |
| 42 | # define OS_CODE 0x03 /* assume Unix */ | |
| 43 | #endif | |
| 44 | ||
| 45 | /* functions */ | |
| 46 | ||
| 47 | typedef uLong (*check_func) (uLong check, const Byte *buf, | |
| 48 | uInt len); | |
| 49 | ||
| 50 | ||
| 51 | /* checksum functions */ | |
| 52 | ||
| 53 | #define BASE 65521L /* largest prime smaller than 65536 */ | |
| 54 | #define NMAX 5552 | |
| 55 | /* NMAX is the largest n such that 255n(n+1)/2 + (n+1)(BASE-1) <= 2^32-1 */ | |
| 56 | ||
| 57 | #define DO1(buf,i) {s1 += buf[i]; s2 += s1;} | |
| 58 | #define DO2(buf,i) DO1(buf,i); DO1(buf,i+1); | |
| 59 | #define DO4(buf,i) DO2(buf,i); DO2(buf,i+2); | |
| 60 | #define DO8(buf,i) DO4(buf,i); DO4(buf,i+4); | |
| 61 | #define DO16(buf) DO8(buf,0); DO8(buf,8); | |
| 62 | ||
| 63 | /* ========================================================================= */ | |
| 64 | /* | |
| 65 | Update a running Adler-32 checksum with the bytes buf[0..len-1] and | |
| 66 | return the updated checksum. If buf is NULL, this function returns | |
| 67 | the required initial value for the checksum. | |
| 68 | An Adler-32 checksum is almost as reliable as a CRC32 but can be computed | |
| 69 | much faster. Usage example: | |
| 70 | ||
| cb7ae262 | 71 | uLong adler = zlib_adler32(0L, NULL, 0); |
| 1da177e4 LT |
72 | |
| 73 | while (read_buffer(buffer, length) != EOF) { | |
| cb7ae262 | 74 | adler = zlib_adler32(adler, buffer, length); |
| 1da177e4 LT |
75 | } |
| 76 | if (adler != original_adler) error(); | |
| 77 | */ | |
| 78 | static inline uLong zlib_adler32(uLong adler, | |
| 79 | const Byte *buf, | |
| 80 | uInt len) | |
| 81 | { | |
| 82 | unsigned long s1 = adler & 0xffff; | |
| 83 | unsigned long s2 = (adler >> 16) & 0xffff; | |
| 84 | int k; | |
| 85 | ||
| 86 | if (buf == NULL) return 1L; | |
| 87 | ||
| 88 | while (len > 0) { | |
| 89 | k = len < NMAX ? len : NMAX; | |
| 90 | len -= k; | |
| 91 | while (k >= 16) { | |
| 92 | DO16(buf); | |
| 93 | buf += 16; | |
| 94 | k -= 16; | |
| 95 | } | |
| 96 | if (k != 0) do { | |
| 97 | s1 += *buf++; | |
| 98 | s2 += s1; | |
| 99 | } while (--k); | |
| 100 | s1 %= BASE; | |
| 101 | s2 %= BASE; | |
| 102 | } | |
| 103 | return (s2 << 16) | s1; | |
| 104 | } | |
| 105 | ||
| 106 | #endif /* _Z_UTIL_H */ |