【Java】CRC32Utils（CRC-32 工具类）

Java CRC-32 工具类

/**
 * CRC-32
 * 
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名称
多项式
初始值
异或值
Bit反转
  CRC-32
0x04C11DB7
0xFFFFFFFF
0xFFFFFFFF
LSB First
  CRC-32/B
0x04C11DB7
0xFFFFFFFF
0xFFFFFFFF
MSB First
  CRC-32/C
0x1EDC6F41
0xFFFFFFFF
0xFFFFFFFF
LSB First
  CRC-32/D
0xA833982B
0xFFFFFFFF
0xFFFFFFFF
LSB First
  CRC-32/MPEG-2
0x04C11DB7
0xFFFFFFFF
0x00000000
MSB First
  CRC-32/POSIX
0x04C11DB7
0x00000000
0xFFFFFFFF
MSB First
 * 
 * @author unnamed
 *
 */
public class CRC32Utils {

    /**
     * CRC-32
     * 
     * 
     *     
     *         
     *         
     *         
     *         
     *     
     *     
     *         
     *         
     *         
     *         
     *     
     * 
多项式
初始值
异或值
Bit反转
0x04C11DB7
0xFFFFFFFF
0xFFFFFFFF
LSB First
     * 
     * @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
     * 
     * 
     *     
     *         
     *         
     *         
     *         
     *     
     *     
     *         
     *         
     *         
     *         
     *     
     * 
多项式
初始值
异或值
Bit反转
0x04C11DB7
0xFFFFFFFF
0xFFFFFFFF
MSB First
     * 
     * @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
     * 
     * 
     *     
     *         
     *         
     *         
     *         
     *     
     *     
     *         
     *         
     *         
     *         
     *     
     * 
多项式
初始值
异或值
Bit反转
0x1EDC6F41
0xFFFFFFFF
0xFFFFFFFF
LSB First
     * 
     * @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
     * 
     * 
     *     
     *         
     *         
     *         
     *         
     *     
     *     
     *         
     *         
     *         
     *         
     *     
     * 
多项式
初始值
异或值
Bit反转
0xA833982B
0xFFFFFFFF
0xFFFFFFFF
LSB First
     * 
     * @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
     * 
     * 
     *     
     *         
     *         
     *         
     *         
     *     
     *     
     *         
     *         
     *         
     *         
     *     
     * 
多项式
初始值
异或值
Bit反转
0x04C11DB7
0xFFFFFFFF
0x00000000
MSB First
     * 
     * @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
     * 
     * 
     *     
     *         
     *         
     *         
     *         
     *     
     *     
     *         
     *         
     *         
     *         
     *     
     * 
多项式
初始值
异或值
Bit反转
0x04C11DB7
0x00000000
0xFFFFFFFF
MSB First
     * 
     * @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;
    }

}