/*  * This file is part of the UCB release of Plan 9. It is subject to the license * terms in the LICENSE file found in the top-level directory of this * distribution and at http://akaros.cs.berkeley.edu/files/Plan9License. No * part of the UCB release of Plan 9, including this file, may be copied, * modified, propagated, or distributed except according to the terms contained * in the LICENSE file. */ #include <u.h>#include <libc.h>#include <flate.h> enum{	ADLERITERS	= 5552,	/* max iters before can overflow 32 bits */	ADLERBASE	= 65521 /* largest prime smaller than 65536 */}; ulongadler32(ulong adler, void *vbuf, int n){	ulong s1, s2;	uchar *buf, *ebuf;	int m; 	buf = vbuf;	s1 = adler & 0xffff;	s2 = (adler >> 16) & 0xffff;	for(; n >= 16; n -= m){		m = n;		if(m > ADLERITERS)			m = ADLERITERS;		m &= ~15;		for(ebuf = buf + m; buf < ebuf; buf += 16){			s1 += buf[0];			s2 += s1;			s1 += buf[1];			s2 += s1;			s1 += buf[2];			s2 += s1;			s1 += buf[3];			s2 += s1;			s1 += buf[4];			s2 += s1;			s1 += buf[5];			s2 += s1;			s1 += buf[6];			s2 += s1;			s1 += buf[7];			s2 += s1;			s1 += buf[8];			s2 += s1;			s1 += buf[9];			s2 += s1;			s1 += buf[10];			s2 += s1;			s1 += buf[11];			s2 += s1;			s1 += buf[12];			s2 += s1;			s1 += buf[13];			s2 += s1;			s1 += buf[14];			s2 += s1;			s1 += buf[15];			s2 += s1;		}		s1 %= ADLERBASE;		s2 %= ADLERBASE;	}	if(n){		for(ebuf = buf + n; buf < ebuf; buf++){			s1 += buf[0];			s2 += s1;		}		s1 %= ADLERBASE;		s2 %= ADLERBASE;	}	return (s2 << 16) + s1;}