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/* adler32.c -- compute the Adler-32 checksum of a data stream
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* Copyright (C) 1995-2002 Mark Adler
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* For conditions of distribution and use, see copyright notice in zlib.h
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/* @(#) $Id: adler32.c,v 1.4 2002/04/24 07:55:32 mcr Exp $ */
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#define BASE 65521L /* largest prime smaller than 65536 */
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/* NMAX is the largest n such that 255n(n+1)/2 + (n+1)(BASE-1) <= 2^32-1 */
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#define DO1(buf,i) {s1 += buf[i]; s2 += s1;}
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#define DO2(buf,i) DO1(buf,i); DO1(buf,i+1);
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#define DO4(buf,i) DO2(buf,i); DO2(buf,i+2);
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#define DO8(buf,i) DO4(buf,i); DO4(buf,i+4);
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#define DO16(buf) DO8(buf,0); DO8(buf,8);
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/* ========================================================================= */
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uLong ZEXPORT adler32(adler, buf, len)
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unsigned long s1 = adler & 0xffff;
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unsigned long s2 = (adler >> 16) & 0xffff;
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if (buf == Z_NULL) return 1L;
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k = len < NMAX ? len : NMAX;
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return (s2 << 16) | s1;