/* zutil.h -- internal interface and configuration of the compression library * Copyright (C) 1995-1998 Jean-loup Gailly. * For conditions of distribution and use, see copyright notice in zlib.h */ /* WARNING: this file should *not* be used by applications. It is part of the implementation of the compression library and is subject to change. Applications should only use zlib.h. */ /* @(#) $Id: zutil.h,v 1.1 2000/01/01 03:32:23 davem Exp $ */ #ifndef _Z_UTIL_H #define _Z_UTIL_H #include <linux/zlib.h> #include <linux/string.h> #include <linux/kernel.h> typedef unsigned char uch; typedef unsigned short ush; typedef unsigned long ulg; /* common constants */ #define STORED_BLOCK 0 #define STATIC_TREES 1 #define DYN_TREES 2 /* The three kinds of block type */ #define MIN_MATCH 3 #define MAX_MATCH 258 /* The minimum and maximum match lengths */ #define PRESET_DICT 0x20 /* preset dictionary flag in zlib header */ /* target dependencies */ /* Common defaults */ #ifndef OS_CODE # define OS_CODE 0x03 /* assume Unix */ #endif /* functions */ typedef uLong (*check_func) (uLong check, const Byte *buf, uInt len); /* checksum functions */ #define BASE 65521L /* largest prime smaller than 65536 */ #define NMAX 5552 /* NMAX is the largest n such that 255n(n+1)/2 + (n+1)(BASE-1) <= 2^32-1 */ #define DO1(buf,i) {s1 += buf[i]; s2 += s1;} #define DO2(buf,i) DO1(buf,i); DO1(buf,i+1); #define DO4(buf,i) DO2(buf,i); DO2(buf,i+2); #define DO8(buf,i) DO4(buf,i); DO4(buf,i+4); #define DO16(buf) DO8(buf,0); DO8(buf,8); /* ========================================================================= */ /* Update a running Adler-32 checksum with the bytes buf[0..len-1] and return the updated checksum. If buf is NULL, this function returns the required initial value for the checksum. An Adler-32 checksum is almost as reliable as a CRC32 but can be computed much faster. Usage example: uLong adler = zlib_adler32(0L, NULL, 0); while (read_buffer(buffer, length) != EOF) { adler = zlib_adler32(adler, buffer, length); } if (adler != original_adler) error(); */ static inline uLong zlib_adler32(uLong adler, const Byte *buf, uInt len) { unsigned long s1 = adler & 0xffff; unsigned long s2 = (adler >> 16) & 0xffff; int k; if (buf == NULL) return 1L; while (len > 0) { k = len < NMAX ? len : NMAX; len -= k; while (k >= 16) { DO16(buf); buf += 16; k -= 16; } if (k != 0) do { s1 += *buf++; s2 += s1; } while (--k); s1 %= BASE; s2 %= BASE; } return (s2 << 16) | s1; } #endif /* _Z_UTIL_H */