akaros/kern/include/zutil.h
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   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#pragma once
  14
  15#include <zlib.h>
  16#include <string.h>
  17
  18typedef unsigned char  uch;
  19typedef unsigned short ush;
  20typedef unsigned long  ulg;
  21
  22        /* common constants */
  23
  24#define STORED_BLOCK 0
  25#define STATIC_TREES 1
  26#define DYN_TREES    2
  27/* The three kinds of block type */
  28
  29#define MIN_MATCH  3
  30#define MAX_MATCH  258
  31/* The minimum and maximum match lengths */
  32
  33#define PRESET_DICT 0x20 /* preset dictionary flag in zlib header */
  34
  35        /* target dependencies */
  36
  37        /* Common defaults */
  38
  39#ifndef OS_CODE
  40#  define OS_CODE  0x03  /* assume Unix */
  41#endif
  42
  43         /* functions */
  44
  45typedef uLong (*check_func) (uLong check, const Byte *buf,
  46                                       uInt len);
  47
  48
  49                        /* checksum functions */
  50
  51#define BASE 65521L /* largest prime smaller than 65536 */
  52#define NMAX 5552
  53/* NMAX is the largest n such that 255n(n+1)/2 + (n+1)(BASE-1) <= 2^32-1 */
  54
  55#define DO1(buf,i)  {s1 += buf[i]; s2 += s1;}
  56#define DO2(buf,i)  DO1(buf,i); DO1(buf,i+1);
  57#define DO4(buf,i)  DO2(buf,i); DO2(buf,i+2);
  58#define DO8(buf,i)  DO4(buf,i); DO4(buf,i+4);
  59#define DO16(buf)   DO8(buf,0); DO8(buf,8);
  60
  61/* ========================================================================= */
  62/*
  63     Update a running Adler-32 checksum with the bytes buf[0..len-1] and
  64   return the updated checksum. If buf is NULL, this function returns
  65   the required initial value for the checksum.
  66   An Adler-32 checksum is almost as reliable as a CRC32 but can be computed
  67   much faster. Usage example:
  68
  69     uLong adler = adler32(0L, NULL, 0);
  70
  71     while (read_buffer(buffer, length) != EOF) {
  72       adler = adler32(adler, buffer, length);
  73     }
  74     if (adler != original_adler) error();
  75*/
  76static inline uLong zlib_adler32(uLong adler,
  77                                 const Byte *buf,
  78                                 uInt len)
  79{
  80    unsigned long s1 = adler & 0xffff;
  81    unsigned long s2 = (adler >> 16) & 0xffff;
  82    int k;
  83
  84    if (buf == NULL) return 1L;
  85
  86    while (len > 0) {
  87        k = len < NMAX ? len : NMAX;
  88        len -= k;
  89        while (k >= 16) {
  90            DO16(buf);
  91            buf += 16;
  92            k -= 16;
  93        }
  94        if (k != 0) do {
  95            s1 += *buf++;
  96            s2 += s1;
  97        } while (--k);
  98        s1 %= BASE;
  99        s2 %= BASE;
 100    }
 101    return (s2 << 16) | s1;
 102}
 103