jdk/src/share/native/java/util/zip/zlib-1.1.3/zcrc32.c - platform/libcore - Gitiles

 /*
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify it
  * under the terms of the GNU General Public License version 2 only, as
  * published by the Free Software Foundation.  Sun designates this
  * particular file as subject to the "Classpath" exception as provided
  * by Sun in the LICENSE file that accompanied this code.
  *
  * This code is distributed in the hope that it will be useful, but WITHOUT
  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  * version 2 for more details (a copy is included in the LICENSE file that
  * accompanied this code).
  *
  * You should have received a copy of the GNU General Public License version
  * 2 along with this work; if not, write to the Free Software Foundation,
  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
  *
  * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
  * CA 95054 USA or visit www.sun.com if you need additional information or
  * have any questions.
  *
  * THIS FILE WAS MODIFIED BY SUN MICROSYSTEMS, INC.
  */

 /*
  * This file is available under and governed by the GNU General Public
  * License version 2 only, as published by the Free Software Foundation.
  * However, the following notice accompanied the original version of this
  * file and, per its terms, should not be removed:
  *
  * crc32.c -- compute the CRC-32 of a data stream
  * Copyright (C) 1995-1998 Mark Adler
  * For conditions of distribution and use, see copyright notice in zlib.h
  */

 #include "zlib.h"

 #define local static

 #ifdef DYNAMIC_CRC_TABLE

 local int crc_table_empty = 1;
 local uLongf crc_table[256];
 local void make_crc_table OF((void));

 /*
   Generate a table for a byte-wise 32-bit CRC calculation on the polynomial:
   x^32+x^26+x^23+x^22+x^16+x^12+x^11+x^10+x^8+x^7+x^5+x^4+x^2+x+1.

   Polynomials over GF(2) are represented in binary, one bit per coefficient,
   with the lowest powers in the most significant bit.  Then adding polynomials
   is just exclusive-or, and multiplying a polynomial by x is a right shift by
   one.  If we call the above polynomial p, and represent a byte as the
   polynomial q, also with the lowest power in the most significant bit (so the
   byte 0xb1 is the polynomial x^7+x^3+x+1), then the CRC is (q*x^32) mod p,
   where a mod b means the remainder after dividing a by b.

   This calculation is done using the shift-register method of multiplying and
   taking the remainder.  The register is initialized to zero, and for each
   incoming bit, x^32 is added mod p to the register if the bit is a one (where
   x^32 mod p is p+x^32 = x^26+...+1), and the register is multiplied mod p by
   x (which is shifting right by one and adding x^32 mod p if the bit shifted
   out is a one).  We start with the highest power (least significant bit) of
   q and repeat for all eight bits of q.

   The table is simply the CRC of all possible eight bit values.  This is all
   the information needed to generate CRC's on data a byte at a time for all
   combinations of CRC register values and incoming bytes.
 */
 local void make_crc_table()
 {
   uLong c;
   int n, k;
   uLong poly;            /* polynomial exclusive-or pattern */
   /* terms of polynomial defining this crc (except x^32): */
   static const Byte p[] = {0,1,2,4,5,7,8,10,11,12,16,22,23,26};

   /* make exclusive-or pattern from polynomial (0xedb88320UL) */
   poly = 0UL;
   for (n = 0; n < sizeof(p)/sizeof(Byte); n++)
     poly |= 1L << (31 - p[n]);

   for (n = 0; n < 256; n++)
   {
     c = (uLong)n;
     for (k = 0; k < 8; k++)
       c = c & 1 ? poly ^ (c >> 1) : c >> 1;
     crc_table[n] = c;
   }
   crc_table_empty = 0;
 }
 #else
 /* ========================================================================
  * Table of CRC-32's of all single-byte values (made by make_crc_table)
  */
 local const uLongf crc_table[256] = {
   0x00000000UL, 0x77073096UL, 0xee0e612cUL, 0x990951baUL, 0x076dc419UL,
   0x706af48fUL, 0xe963a535UL, 0x9e6495a3UL, 0x0edb8832UL, 0x79dcb8a4UL,
   0xe0d5e91eUL, 0x97d2d988UL, 0x09b64c2bUL, 0x7eb17cbdUL, 0xe7b82d07UL,
   0x90bf1d91UL, 0x1db71064UL, 0x6ab020f2UL, 0xf3b97148UL, 0x84be41deUL,
   0x1adad47dUL, 0x6ddde4ebUL, 0xf4d4b551UL, 0x83d385c7UL, 0x136c9856UL,
   0x646ba8c0UL, 0xfd62f97aUL, 0x8a65c9ecUL, 0x14015c4fUL, 0x63066cd9UL,
   0xfa0f3d63UL, 0x8d080df5UL, 0x3b6e20c8UL, 0x4c69105eUL, 0xd56041e4UL,
   0xa2677172UL, 0x3c03e4d1UL, 0x4b04d447UL, 0xd20d85fdUL, 0xa50ab56bUL,
   0x35b5a8faUL, 0x42b2986cUL, 0xdbbbc9d6UL, 0xacbcf940UL, 0x32d86ce3UL,
   0x45df5c75UL, 0xdcd60dcfUL, 0xabd13d59UL, 0x26d930acUL, 0x51de003aUL,
   0xc8d75180UL, 0xbfd06116UL, 0x21b4f4b5UL, 0x56b3c423UL, 0xcfba9599UL,
   0xb8bda50fUL, 0x2802b89eUL, 0x5f058808UL, 0xc60cd9b2UL, 0xb10be924UL,
   0x2f6f7c87UL, 0x58684c11UL, 0xc1611dabUL, 0xb6662d3dUL, 0x76dc4190UL,
   0x01db7106UL, 0x98d220bcUL, 0xefd5102aUL, 0x71b18589UL, 0x06b6b51fUL,
   0x9fbfe4a5UL, 0xe8b8d433UL, 0x7807c9a2UL, 0x0f00f934UL, 0x9609a88eUL,
   0xe10e9818UL, 0x7f6a0dbbUL, 0x086d3d2dUL, 0x91646c97UL, 0xe6635c01UL,
   0x6b6b51f4UL, 0x1c6c6162UL, 0x856530d8UL, 0xf262004eUL, 0x6c0695edUL,
   0x1b01a57bUL, 0x8208f4c1UL, 0xf50fc457UL, 0x65b0d9c6UL, 0x12b7e950UL,
   0x8bbeb8eaUL, 0xfcb9887cUL, 0x62dd1ddfUL, 0x15da2d49UL, 0x8cd37cf3UL,
   0xfbd44c65UL, 0x4db26158UL, 0x3ab551ceUL, 0xa3bc0074UL, 0xd4bb30e2UL,
   0x4adfa541UL, 0x3dd895d7UL, 0xa4d1c46dUL, 0xd3d6f4fbUL, 0x4369e96aUL,
   0x346ed9fcUL, 0xad678846UL, 0xda60b8d0UL, 0x44042d73UL, 0x33031de5UL,
   0xaa0a4c5fUL, 0xdd0d7cc9UL, 0x5005713cUL, 0x270241aaUL, 0xbe0b1010UL,
   0xc90c2086UL, 0x5768b525UL, 0x206f85b3UL, 0xb966d409UL, 0xce61e49fUL,
   0x5edef90eUL, 0x29d9c998UL, 0xb0d09822UL, 0xc7d7a8b4UL, 0x59b33d17UL,
   0x2eb40d81UL, 0xb7bd5c3bUL, 0xc0ba6cadUL, 0xedb88320UL, 0x9abfb3b6UL,
   0x03b6e20cUL, 0x74b1d29aUL, 0xead54739UL, 0x9dd277afUL, 0x04db2615UL,
   0x73dc1683UL, 0xe3630b12UL, 0x94643b84UL, 0x0d6d6a3eUL, 0x7a6a5aa8UL,
   0xe40ecf0bUL, 0x9309ff9dUL, 0x0a00ae27UL, 0x7d079eb1UL, 0xf00f9344UL,
   0x8708a3d2UL, 0x1e01f268UL, 0x6906c2feUL, 0xf762575dUL, 0x806567cbUL,
   0x196c3671UL, 0x6e6b06e7UL, 0xfed41b76UL, 0x89d32be0UL, 0x10da7a5aUL,
   0x67dd4accUL, 0xf9b9df6fUL, 0x8ebeeff9UL, 0x17b7be43UL, 0x60b08ed5UL,
   0xd6d6a3e8UL, 0xa1d1937eUL, 0x38d8c2c4UL, 0x4fdff252UL, 0xd1bb67f1UL,
   0xa6bc5767UL, 0x3fb506ddUL, 0x48b2364bUL, 0xd80d2bdaUL, 0xaf0a1b4cUL,
   0x36034af6UL, 0x41047a60UL, 0xdf60efc3UL, 0xa867df55UL, 0x316e8eefUL,
   0x4669be79UL, 0xcb61b38cUL, 0xbc66831aUL, 0x256fd2a0UL, 0x5268e236UL,
   0xcc0c7795UL, 0xbb0b4703UL, 0x220216b9UL, 0x5505262fUL, 0xc5ba3bbeUL,
   0xb2bd0b28UL, 0x2bb45a92UL, 0x5cb36a04UL, 0xc2d7ffa7UL, 0xb5d0cf31UL,
   0x2cd99e8bUL, 0x5bdeae1dUL, 0x9b64c2b0UL, 0xec63f226UL, 0x756aa39cUL,
   0x026d930aUL, 0x9c0906a9UL, 0xeb0e363fUL, 0x72076785UL, 0x05005713UL,
   0x95bf4a82UL, 0xe2b87a14UL, 0x7bb12baeUL, 0x0cb61b38UL, 0x92d28e9bUL,
   0xe5d5be0dUL, 0x7cdcefb7UL, 0x0bdbdf21UL, 0x86d3d2d4UL, 0xf1d4e242UL,
   0x68ddb3f8UL, 0x1fda836eUL, 0x81be16cdUL, 0xf6b9265bUL, 0x6fb077e1UL,
   0x18b74777UL, 0x88085ae6UL, 0xff0f6a70UL, 0x66063bcaUL, 0x11010b5cUL,
   0x8f659effUL, 0xf862ae69UL, 0x616bffd3UL, 0x166ccf45UL, 0xa00ae278UL,
   0xd70dd2eeUL, 0x4e048354UL, 0x3903b3c2UL, 0xa7672661UL, 0xd06016f7UL,
   0x4969474dUL, 0x3e6e77dbUL, 0xaed16a4aUL, 0xd9d65adcUL, 0x40df0b66UL,
   0x37d83bf0UL, 0xa9bcae53UL, 0xdebb9ec5UL, 0x47b2cf7fUL, 0x30b5ffe9UL,
   0xbdbdf21cUL, 0xcabac28aUL, 0x53b39330UL, 0x24b4a3a6UL, 0xbad03605UL,
   0xcdd70693UL, 0x54de5729UL, 0x23d967bfUL, 0xb3667a2eUL, 0xc4614ab8UL,
   0x5d681b02UL, 0x2a6f2b94UL, 0xb40bbe37UL, 0xc30c8ea1UL, 0x5a05df1bUL,
   0x2d02ef8dUL
 };
 #endif

 /* =========================================================================
  * This function can be used by asm versions of crc32()
  */
 const uLongf * ZEXPORT get_crc_table()
 {
 #ifdef DYNAMIC_CRC_TABLE
   if (crc_table_empty) make_crc_table();
 #endif
   return (const uLongf *)crc_table;
 }

 /* ========================================================================= */
 #define DO1(buf) crc = crc_table[((int)crc ^ (*buf++)) & 0xff] ^ (crc >> 8);
 #define DO2(buf)  DO1(buf); DO1(buf);
 #define DO4(buf)  DO2(buf); DO2(buf);
 #define DO8(buf)  DO4(buf); DO4(buf);

 /* ========================================================================= */
 uLong ZEXPORT crc32(crc, buf, len)
     uLong crc;
     const Bytef *buf;
     uInt len;
 {
     if (buf == Z_NULL) return 0UL;
 #ifdef DYNAMIC_CRC_TABLE
     if (crc_table_empty)
       make_crc_table();
 #endif
     crc = crc ^ 0xffffffffUL;
     while (len >= 8)
     {
       DO8(buf);
       len -= 8;
     }
     if (len) do {
       DO1(buf);
     } while (--len);
     return crc ^ 0xffffffffUL;
 }
	/*
	* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
	*
	* This code is free software; you can redistribute it and/or modify it
	* under the terms of the GNU General Public License version 2 only, as
	* published by the Free Software Foundation. Sun designates this
	* particular file as subject to the "Classpath" exception as provided
	* by Sun in the LICENSE file that accompanied this code.
	*
	* This code is distributed in the hope that it will be useful, but WITHOUT
	* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
	* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
	* version 2 for more details (a copy is included in the LICENSE file that
	* accompanied this code).
	*
	* You should have received a copy of the GNU General Public License version
	* 2 along with this work; if not, write to the Free Software Foundation,
	* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
	*
	* Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
	* CA 95054 USA or visit www.sun.com if you need additional information or
	* have any questions.
	*
	* THIS FILE WAS MODIFIED BY SUN MICROSYSTEMS, INC.
	*/

	/*
	* This file is available under and governed by the GNU General Public
	* License version 2 only, as published by the Free Software Foundation.
	* However, the following notice accompanied the original version of this
	* file and, per its terms, should not be removed:
	*
	* crc32.c -- compute the CRC-32 of a data stream
	* Copyright (C) 1995-1998 Mark Adler
	* For conditions of distribution and use, see copyright notice in zlib.h
	*/

	#include "zlib.h"

	#define local static

	#ifdef DYNAMIC_CRC_TABLE

	local int crc_table_empty = 1;
	local uLongf crc_table[256];
	local void make_crc_table OF((void));

	/*
	Generate a table for a byte-wise 32-bit CRC calculation on the polynomial:
	x^32+x^26+x^23+x^22+x^16+x^12+x^11+x^10+x^8+x^7+x^5+x^4+x^2+x+1.

	Polynomials over GF(2) are represented in binary, one bit per coefficient,
	with the lowest powers in the most significant bit. Then adding polynomials
	is just exclusive-or, and multiplying a polynomial by x is a right shift by
	one. If we call the above polynomial p, and represent a byte as the
	polynomial q, also with the lowest power in the most significant bit (so the
	byte 0xb1 is the polynomial x^7+x^3+x+1), then the CRC is (q*x^32) mod p,
	where a mod b means the remainder after dividing a by b.

	This calculation is done using the shift-register method of multiplying and
	taking the remainder. The register is initialized to zero, and for each
	incoming bit, x^32 is added mod p to the register if the bit is a one (where
	x^32 mod p is p+x^32 = x^26+...+1), and the register is multiplied mod p by
	x (which is shifting right by one and adding x^32 mod p if the bit shifted
	out is a one). We start with the highest power (least significant bit) of
	q and repeat for all eight bits of q.

	The table is simply the CRC of all possible eight bit values. This is all
	the information needed to generate CRC's on data a byte at a time for all
	combinations of CRC register values and incoming bytes.
	*/
	local void make_crc_table()
	{
	uLong c;
	int n, k;
	uLong poly; /* polynomial exclusive-or pattern */
	/* terms of polynomial defining this crc (except x^32): */
	static const Byte p[] = {0,1,2,4,5,7,8,10,11,12,16,22,23,26};

	/* make exclusive-or pattern from polynomial (0xedb88320UL) */
	poly = 0UL;
	for (n = 0; n < sizeof(p)/sizeof(Byte); n++)
	poly \|= 1L << (31 - p[n]);

	for (n = 0; n < 256; n++)
	{
	c = (uLong)n;
	for (k = 0; k < 8; k++)
	c = c & 1 ? poly ^ (c >> 1) : c >> 1;
	crc_table[n] = c;
	}
	crc_table_empty = 0;
	}
	#else
	/* ========================================================================
	* Table of CRC-32's of all single-byte values (made by make_crc_table)
	*/
	local const uLongf crc_table[256] = {
	0x00000000UL, 0x77073096UL, 0xee0e612cUL, 0x990951baUL, 0x076dc419UL,
	0x706af48fUL, 0xe963a535UL, 0x9e6495a3UL, 0x0edb8832UL, 0x79dcb8a4UL,
	0xe0d5e91eUL, 0x97d2d988UL, 0x09b64c2bUL, 0x7eb17cbdUL, 0xe7b82d07UL,
	0x90bf1d91UL, 0x1db71064UL, 0x6ab020f2UL, 0xf3b97148UL, 0x84be41deUL,
	0x1adad47dUL, 0x6ddde4ebUL, 0xf4d4b551UL, 0x83d385c7UL, 0x136c9856UL,
	0x646ba8c0UL, 0xfd62f97aUL, 0x8a65c9ecUL, 0x14015c4fUL, 0x63066cd9UL,
	0xfa0f3d63UL, 0x8d080df5UL, 0x3b6e20c8UL, 0x4c69105eUL, 0xd56041e4UL,
	0xa2677172UL, 0x3c03e4d1UL, 0x4b04d447UL, 0xd20d85fdUL, 0xa50ab56bUL,
	0x35b5a8faUL, 0x42b2986cUL, 0xdbbbc9d6UL, 0xacbcf940UL, 0x32d86ce3UL,
	0x45df5c75UL, 0xdcd60dcfUL, 0xabd13d59UL, 0x26d930acUL, 0x51de003aUL,
	0xc8d75180UL, 0xbfd06116UL, 0x21b4f4b5UL, 0x56b3c423UL, 0xcfba9599UL,
	0xb8bda50fUL, 0x2802b89eUL, 0x5f058808UL, 0xc60cd9b2UL, 0xb10be924UL,
	0x2f6f7c87UL, 0x58684c11UL, 0xc1611dabUL, 0xb6662d3dUL, 0x76dc4190UL,
	0x01db7106UL, 0x98d220bcUL, 0xefd5102aUL, 0x71b18589UL, 0x06b6b51fUL,
	0x9fbfe4a5UL, 0xe8b8d433UL, 0x7807c9a2UL, 0x0f00f934UL, 0x9609a88eUL,
	0xe10e9818UL, 0x7f6a0dbbUL, 0x086d3d2dUL, 0x91646c97UL, 0xe6635c01UL,
	0x6b6b51f4UL, 0x1c6c6162UL, 0x856530d8UL, 0xf262004eUL, 0x6c0695edUL,
	0x1b01a57bUL, 0x8208f4c1UL, 0xf50fc457UL, 0x65b0d9c6UL, 0x12b7e950UL,
	0x8bbeb8eaUL, 0xfcb9887cUL, 0x62dd1ddfUL, 0x15da2d49UL, 0x8cd37cf3UL,
	0xfbd44c65UL, 0x4db26158UL, 0x3ab551ceUL, 0xa3bc0074UL, 0xd4bb30e2UL,
	0x4adfa541UL, 0x3dd895d7UL, 0xa4d1c46dUL, 0xd3d6f4fbUL, 0x4369e96aUL,
	0x346ed9fcUL, 0xad678846UL, 0xda60b8d0UL, 0x44042d73UL, 0x33031de5UL,
	0xaa0a4c5fUL, 0xdd0d7cc9UL, 0x5005713cUL, 0x270241aaUL, 0xbe0b1010UL,
	0xc90c2086UL, 0x5768b525UL, 0x206f85b3UL, 0xb966d409UL, 0xce61e49fUL,
	0x5edef90eUL, 0x29d9c998UL, 0xb0d09822UL, 0xc7d7a8b4UL, 0x59b33d17UL,
	0x2eb40d81UL, 0xb7bd5c3bUL, 0xc0ba6cadUL, 0xedb88320UL, 0x9abfb3b6UL,
	0x03b6e20cUL, 0x74b1d29aUL, 0xead54739UL, 0x9dd277afUL, 0x04db2615UL,
	0x73dc1683UL, 0xe3630b12UL, 0x94643b84UL, 0x0d6d6a3eUL, 0x7a6a5aa8UL,
	0xe40ecf0bUL, 0x9309ff9dUL, 0x0a00ae27UL, 0x7d079eb1UL, 0xf00f9344UL,
	0x8708a3d2UL, 0x1e01f268UL, 0x6906c2feUL, 0xf762575dUL, 0x806567cbUL,
	0x196c3671UL, 0x6e6b06e7UL, 0xfed41b76UL, 0x89d32be0UL, 0x10da7a5aUL,
	0x67dd4accUL, 0xf9b9df6fUL, 0x8ebeeff9UL, 0x17b7be43UL, 0x60b08ed5UL,
	0xd6d6a3e8UL, 0xa1d1937eUL, 0x38d8c2c4UL, 0x4fdff252UL, 0xd1bb67f1UL,
	0xa6bc5767UL, 0x3fb506ddUL, 0x48b2364bUL, 0xd80d2bdaUL, 0xaf0a1b4cUL,
	0x36034af6UL, 0x41047a60UL, 0xdf60efc3UL, 0xa867df55UL, 0x316e8eefUL,
	0x4669be79UL, 0xcb61b38cUL, 0xbc66831aUL, 0x256fd2a0UL, 0x5268e236UL,
	0xcc0c7795UL, 0xbb0b4703UL, 0x220216b9UL, 0x5505262fUL, 0xc5ba3bbeUL,
	0xb2bd0b28UL, 0x2bb45a92UL, 0x5cb36a04UL, 0xc2d7ffa7UL, 0xb5d0cf31UL,
	0x2cd99e8bUL, 0x5bdeae1dUL, 0x9b64c2b0UL, 0xec63f226UL, 0x756aa39cUL,
	0x026d930aUL, 0x9c0906a9UL, 0xeb0e363fUL, 0x72076785UL, 0x05005713UL,
	0x95bf4a82UL, 0xe2b87a14UL, 0x7bb12baeUL, 0x0cb61b38UL, 0x92d28e9bUL,
	0xe5d5be0dUL, 0x7cdcefb7UL, 0x0bdbdf21UL, 0x86d3d2d4UL, 0xf1d4e242UL,
	0x68ddb3f8UL, 0x1fda836eUL, 0x81be16cdUL, 0xf6b9265bUL, 0x6fb077e1UL,
	0x18b74777UL, 0x88085ae6UL, 0xff0f6a70UL, 0x66063bcaUL, 0x11010b5cUL,
	0x8f659effUL, 0xf862ae69UL, 0x616bffd3UL, 0x166ccf45UL, 0xa00ae278UL,
	0xd70dd2eeUL, 0x4e048354UL, 0x3903b3c2UL, 0xa7672661UL, 0xd06016f7UL,
	0x4969474dUL, 0x3e6e77dbUL, 0xaed16a4aUL, 0xd9d65adcUL, 0x40df0b66UL,
	0x37d83bf0UL, 0xa9bcae53UL, 0xdebb9ec5UL, 0x47b2cf7fUL, 0x30b5ffe9UL,
	0xbdbdf21cUL, 0xcabac28aUL, 0x53b39330UL, 0x24b4a3a6UL, 0xbad03605UL,
	0xcdd70693UL, 0x54de5729UL, 0x23d967bfUL, 0xb3667a2eUL, 0xc4614ab8UL,
	0x5d681b02UL, 0x2a6f2b94UL, 0xb40bbe37UL, 0xc30c8ea1UL, 0x5a05df1bUL,
	0x2d02ef8dUL
	};
	#endif

	/* =========================================================================
	* This function can be used by asm versions of crc32()
	*/
	const uLongf * ZEXPORT get_crc_table()
	{
	#ifdef DYNAMIC_CRC_TABLE
	if (crc_table_empty) make_crc_table();
	#endif
	return (const uLongf *)crc_table;
	}

	/* ========================================================================= */
	#define DO1(buf) crc = crc_table[((int)crc ^ (*buf++)) & 0xff] ^ (crc >> 8);
	#define DO2(buf) DO1(buf); DO1(buf);
	#define DO4(buf) DO2(buf); DO2(buf);
	#define DO8(buf) DO4(buf); DO4(buf);

	/* ========================================================================= */
	uLong ZEXPORT crc32(crc, buf, len)
	uLong crc;
	const Bytef *buf;
	uInt len;
	{
	if (buf == Z_NULL) return 0UL;
	#ifdef DYNAMIC_CRC_TABLE
	if (crc_table_empty)
	make_crc_table();
	#endif
	crc = crc ^ 0xffffffffUL;
	while (len >= 8)
	{
	DO8(buf);
	len -= 8;
	}
	if (len) do {
	DO1(buf);
	} while (--len);
	return crc ^ 0xffffffffUL;
	}