adler32.cc File Reference

#include "zlib.h"

Go to the source code of this file.

Macros
#define	ZLIB_INTERNAL
#define	BASE   65521UL /* largest prime smaller than 65536 */
#define	NMAX   5552
#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);
#define	MOD(a)   a %= BASE

Functions
uLong ZEXPORT	adler32 (uLong adler, const Bytef *buf, uInt len)

Macro Definition Documentation

BASE

#define BASE   65521UL /* largest prime smaller than 65536 */

Definition at line 11 of file adler32.cc.

DO1

#define DO1	(		buf,
			i
	)		{s1 += buf[i]; s2 += s1;}

Definition at line 15 of file adler32.cc.

DO16

#define DO16

(

buf

)

DO8(buf,0); DO8(buf,8);

Definition at line 19 of file adler32.cc.

DO2

#define DO2	(		buf,
			i
	)		DO1(buf,i); DO1(buf,i+1);

Definition at line 16 of file adler32.cc.

DO4

#define DO4	(		buf,
			i
	)		DO2(buf,i); DO2(buf,i+2);

Definition at line 17 of file adler32.cc.

DO8

#define DO8	(		buf,
			i
	)		DO4(buf,i); DO4(buf,i+4);

Definition at line 18 of file adler32.cc.

MOD

#define MOD

(

a

)

a %= BASE

Definition at line 43 of file adler32.cc.

NMAX

#define NMAX   5552

Definition at line 12 of file adler32.cc.

ZLIB_INTERNAL

#define ZLIB_INTERNAL

Definition at line 8 of file adler32.cc.

Function Documentation

adler32()

uLong ZEXPORT adler32	(	uLong	adler,
		const Bytef *	buf,
		uInt	len
	)

Definition at line 47 of file adler32.cc.

{
    unsigned long s1 = adler & 0xffff;
    unsigned long s2 = (adler >> 16) & 0xffff;
    int k;
 
    if (buf == Z_NULL) return 1L;
 
    while (len > 0) {
        k = len < NMAX ? (int)len : NMAX;
        len -= k;
        while (k >= 16) {
            DO16(buf);
            buf += 16;
            k -= 16;
        }
        if (k != 0) do {
            s1 += *buf++;
            s2 += s1;
        } while (--k);
        MOD(s1);
        MOD(s2);
    }
    return (s2 << 16) | s1;
}

Referenced by deflate(), deflateReset(), deflateSetDictionary(), and read_buf().