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 20 typedef unsigned char uch; 21 typedef unsigned short ush; 22 typedef 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 59 typedef 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 */ 90 static 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 */ 119