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26 package java.util.zip;
29 * A class that can be used to compute the CRC-32 of a data stream.
32 * @author David Connelly
35 class CRC32 implements Checksum {
39 * Creates a new CRC32 object.
46 * Updates the CRC-32 checksum with the specified byte (the low
47 * eight bits of the argument b).
49 * @param b the byte to update the checksum with
51 public void update(int b) {
56 * Updates the CRC-32 checksum with the specified array of bytes.
58 public void update(byte[] b, int off, int len) {
60 throw new NullPointerException();
62 if (off < 0 || len < 0 || off > b.length - len) {
63 throw new ArrayIndexOutOfBoundsException();
65 crc = updateBytes(crc, b, off, len);
69 * Updates the CRC-32 checksum with the specified array of bytes.
71 * @param b the array of bytes to update the checksum with
73 public void update(byte[] b) {
74 crc = updateBytes(crc, b, 0, b.length);
78 * Resets CRC-32 to initial value.
85 * Returns CRC-32 value.
87 public long getValue() {
88 return (long)crc & 0xffffffffL;
91 private native static int update(int crc, int b);
92 private native static int updateBytes(int crc, byte[] b, int off, int len);