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/* $MirOS: contrib/hosted/fwcf/adler.h,v 1.10 2007/05/07 16:15:56 tg Exp $ */
/*-
* Copyright (c) 2006, 2007
* Thorsten Glaser <tg@mirbsd.de>
* The adler32 algorithm is
* Copyright (C) 1995 Mark Adler
*
* Provided that these terms and disclaimer and all copyright notices
* are retained or reproduced in an accompanying document, permission
* is granted to deal in this work without restriction, including un-
* limited rights to use, publicly perform, distribute, sell, modify,
* merge, give away, or sublicence.
*
* This work is provided "AS IS" and WITHOUT WARRANTY of any kind, to
* the utmost extent permitted by applicable law, neither express nor
* implied; without malicious intent or gross negligence. In no event
* may a licensor, author or contributor be held liable for indirect,
* direct, other damage, loss, or other issues arising in any way out
* of dealing in the work, even if advised of the possibility of such
* damage or existence of a defect, except proven that it results out
* of said person's immediate fault when using the work as intended.
*-
* See also:
* contrib/hosted/fwcf/adler.h
* src/lib/libc/hash/adh32.c
* src/kern/z/adler32s.c
* src/kern/z/adler32_i386.S
*/
#ifndef ADLER_H
#define ADLER_H "$MirOS: contrib/hosted/fwcf/adler.h,v 1.10 2007/05/07 16:15:56 tg Exp $"
/*
* ADLER-32 implementation
*/
#define ADLER_BASE 65521 /* largest prime smaller than 65536 */
#define ADLER_NMAX 5552 /* largest n: 255n(n+1)/2 + (n+1)(BASE-1) <= 2^32-1 */
/* declare everything needed by the adler32 routine */
#define ADLER_DECL unsigned s1 = 1, s2 = 0, n
/* calculate the adler32 crc of the data pointed to
by the 'buffer' argument, size expected in 'len'
which is TRASHED; stores the result in s1 and s2 */
#define ADLER_CALC(buffer) do { \
const uint8_t *adler_buf = (const uint8_t *)(buffer); \
while (len) { \
len -= (n = MIN(len, ADLER_NMAX)); \
while (n--) { \
s1 += *adler_buf++; \
s2 += s1; \
} \
s1 %= ADLER_BASE; \
s2 %= ADLER_BASE; \
} \
} while (0)
#endif
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