[linux.git] / include / linux / zutil.h

/* 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 */

#ifndef DEF_WBITS
#  define DEF_WBITS MAX_WBITS
#endif
/* default windowBits for decompression. MAX_WBITS is for compression only */

#if MAX_MEM_LEVEL >= 8
#  define DEF_MEM_LEVEL 8
#else
#  define DEF_MEM_LEVEL  MAX_MEM_LEVEL
#endif
/* default memLevel */

#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 = adler32(0L, NULL, 0);

     while (read_buffer(buffer, length) != EOF) {
       adler = 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 */
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
	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 */