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 */ 120