Java CRC-32 工具类
/**
* CRC-32
*
* <table width="400px" border="1" cellpadding="0" cellspacing="0">
* <tr>
* <th>名称</th>
* <th>多项式</th>
* <th>初始值</th>
* <th>异或值</th>
* <th>Bit反转</th>
* </tr>
* <tr>
* <td> CRC-32</td>
* <td align="center">0x04C11DB7</td>
* <td align="center">0xFFFFFFFF</td>
* <td align="center">0xFFFFFFFF</td>
* <td align="center">LSB First</td>
* </tr>
* <tr>
* <td> CRC-32/B</td>
* <td align="center">0x04C11DB7</td>
* <td align="center">0xFFFFFFFF</td>
* <td align="center">0xFFFFFFFF</td>
* <td align="center">MSB First</td>
* </tr>
* <tr>
* <td> CRC-32/C</td>
* <td align="center">0x1EDC6F41</td>
* <td align="center">0xFFFFFFFF</td>
* <td align="center">0xFFFFFFFF</td>
* <td align="center">LSB First</td>
* </tr>
* <tr>
* <td> CRC-32/D</td>
* <td align="center">0xA833982B</td>
* <td align="center">0xFFFFFFFF</td>
* <td align="center">0xFFFFFFFF</td>
* <td align="center">LSB First</td>
* </tr>
* <tr>
* <td> CRC-32/MPEG-2</td>
* <td align="center">0x04C11DB7</td>
* <td align="center">0xFFFFFFFF</td>
* <td align="center">0x00000000</td>
* <td align="center">MSB First</td>
* </tr>
* <tr>
* <td> CRC-32/POSIX</td>
* <td align="center">0x04C11DB7</td>
* <td align="center">0x00000000</td>
* <td align="center">0xFFFFFFFF</td>
* <td align="center">MSB First</td>
* </tr>
* </table>
*
* @author unnamed
*
*/
public class CRC32Utils {
/**
* CRC-32
*
* <table width="400px" border="1" cellpadding="0" cellspacing="0">
* <tr>
* <th>多项式</th>
* <th>初始值</th>
* <th>异或值</th>
* <th>Bit反转</th>
* </tr>
* <tr>
* <td align="center">0x04C11DB7</td>
* <td align="center">0xFFFFFFFF</td>
* <td align="center">0xFFFFFFFF</td>
* <td align="center">LSB First</td>
* </tr>
* </table>
*
* @param source
* @param offset
* @param length
* @return
*/
public static long CRC32(byte[] source, int offset, int length) {
long wCRCin = 0xFFFFFFFFL;
// Long.reverse(0x04C11DB7L) >>> 32
long wCPoly = 0xEDB88320L;
for (int i = offset, cnt = offset + length; i < cnt; i++) {
wCRCin ^= ((long) source[i] & 0x000000FFL);
for (int j = 0; j < 8; j++) {
if ((wCRCin & 0x00000001L) != 0) {
wCRCin >>= 1;
wCRCin ^= wCPoly;
} else {
wCRCin >>= 1;
}
}
}
return wCRCin ^= 0xFFFFFFFFL;
}
/**
* CRC-32/B
*
* <table width="400px" border="1" cellpadding="0" cellspacing="0">
* <tr>
* <th>多项式</th>
* <th>初始值</th>
* <th>异或值</th>
* <th>Bit反转</th>
* </tr>
* <tr>
* <td align="center">0x04C11DB7</td>
* <td align="center">0xFFFFFFFF</td>
* <td align="center">0xFFFFFFFF</td>
* <td align="center">MSB First</td>
* </tr>
* </table>
*
* @param source
* @param offset
* @param length
* @return
*/
public static long CRC32_B(byte[] source, int offset, int length) {
long wCRCin = 0xFFFFFFFFL;
long wCPoly = 0x04C11DB7L;
for (int i = offset, cnt = offset + length; i < cnt; i++) {
for (int j = 0; j < 8; j++) {
boolean bit = ((source[i] >> (7 - j) & 1) == 1);
boolean c31 = ((wCRCin >> 31 & 1) == 1);
wCRCin <<= 1;
if (c31 ^ bit) {
wCRCin ^= wCPoly;
}
}
}
wCRCin &= 0xFFFFFFFFL;
return wCRCin ^= 0xFFFFFFFFL;
}
/**
* CRC-32/C
*
* <table width="400px" border="1" cellpadding="0" cellspacing="0">
* <tr>
* <th>多项式</th>
* <th>初始值</th>
* <th>异或值</th>
* <th>Bit反转</th>
* </tr>
* <tr>
* <td align="center">0x1EDC6F41</td>
* <td align="center">0xFFFFFFFF</td>
* <td align="center">0xFFFFFFFF</td>
* <td align="center">LSB First</td>
* </tr>
* </table>
*
* @param source
* @param offset
* @param length
* @return
*/
public static long CRC32_C(byte[] source, int offset, int length) {
long wCRCin = 0xFFFFFFFFL;
// Long.reverse(0x1EDC6F41L) >>> 32
long wCPoly = 0x82F63B78L;
for (int i = offset, cnt = offset + length; i < cnt; i++) {
wCRCin ^= ((long) source[i] & 0x000000FFL);
for (int j = 0; j < 8; j++) {
if ((wCRCin & 0x00000001L) != 0) {
wCRCin >>= 1;
wCRCin ^= wCPoly;
} else {
wCRCin >>= 1;
}
}
}
return wCRCin ^= 0xFFFFFFFFL;
}
/**
* CRC-32/D
*
* <table width="400px" border="1" cellpadding="0" cellspacing="0">
* <tr>
* <th>多项式</th>
* <th>初始值</th>
* <th>异或值</th>
* <th>Bit反转</th>
* </tr>
* <tr>
* <td align="center">0xA833982B</td>
* <td align="center">0xFFFFFFFF</td>
* <td align="center">0xFFFFFFFF</td>
* <td align="center">LSB First</td>
* </tr>
* </table>
*
* @param source
* @param offset
* @param length
* @return
*/
public static long CRC32_D(byte[] source, int offset, int length) {
long wCRCin = 0xFFFFFFFFL;
// Long.reverse(0xA833982BL) >>> 32
long wCPoly = 0xD419CC15L;
for (int i = offset, cnt = offset + length; i < cnt; i++) {
wCRCin ^= ((long) source[i] & 0x000000FFL);
for (int j = 0; j < 8; j++) {
if ((wCRCin & 0x00000001L) != 0) {
wCRCin >>= 1;
wCRCin ^= wCPoly;
} else {
wCRCin >>= 1;
}
}
}
return wCRCin ^= 0xFFFFFFFFL;
}
/**
* CRC-32/MPEG-2
*
* <table width="400px" border="1" cellpadding="0" cellspacing="0">
* <tr>
* <th>多项式</th>
* <th>初始值</th>
* <th>异或值</th>
* <th>Bit反转</th>
* </tr>
* <tr>
* <td align="center">0x04C11DB7</td>
* <td align="center">0xFFFFFFFF</td>
* <td align="center">0x00000000</td>
* <td align="center">MSB First</td>
* </tr>
* </table>
*
* @param source
* @param offset
* @param length
* @return
*/
public static long CRC32_MPEG_2(byte[] source, int offset, int length) {
long wCRCin = 0xFFFFFFFFL;
long wCPoly = 0x04C11DB7L;
for (int i = offset, cnt = offset + length; i < cnt; i++) {
for (int j = 0; j < 8; j++) {
boolean bit = ((source[i] >> (7 - j) & 1) == 1);
boolean c31 = ((wCRCin >> 31 & 1) == 1);
wCRCin <<= 1;
if (c31 ^ bit) {
wCRCin ^= wCPoly;
}
}
}
wCRCin &= 0xFFFFFFFFL;
return wCRCin ^= 0x00000000L;
}
/**
* CRC-32/POSIX
*
* <table width="400px" border="1" cellpadding="0" cellspacing="0">
* <tr>
* <th>多项式</th>
* <th>初始值</th>
* <th>异或值</th>
* <th>Bit反转</th>
* </tr>
* <tr>
* <td align="center">0x04C11DB7</td>
* <td align="center">0x00000000</td>
* <td align="center">0xFFFFFFFF</td>
* <td align="center">MSB First</td>
* </tr>
* </table>
*
* @param source
* @param offset
* @param length
* @return
*/
public static long CRC32_POSIX(byte[] source, int offset, int length) {
long wCRCin = 0x00000000L;
long wCPoly = 0x04C11DB7L;
for (int i = offset, cnt = offset + length; i < cnt; i++) {
for (int j = 0; j < 8; j++) {
boolean bit = ((source[i] >> (7 - j) & 1) == 1);
boolean c31 = ((wCRCin >> 31 & 1) == 1);
wCRCin <<= 1;
if (c31 ^ bit) {
wCRCin ^= wCPoly;
}
}
}
wCRCin &= 0xFFFFFFFFL;
return wCRCin ^= 0xFFFFFFFFL;
}
}
