30 lines
844 B
Java
30 lines
844 B
Java
import java.util.BitSet;
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/**
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* Generates a crc32 checksum for a given string or byte array
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*/
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public class CRC32 {
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public static void main(String[] args) {
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System.out.println(Integer.toHexString(crc32("Hello World")));
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}
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public static int crc32(String str) {
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return crc32(str.getBytes());
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}
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public static int crc32(byte[] data) {
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BitSet bitSet = BitSet.valueOf(data);
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int crc32 = 0xFFFFFFFF; // initial value
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for (int i = 0; i < data.length * 8; i++) {
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if (((crc32 >>> 31) & 1) != (bitSet.get(i) ? 1 : 0))
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crc32 = (crc32 << 1) ^ 0x04C11DB7; // xor with polynomial
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else
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crc32 = (crc32 << 1);
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}
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crc32 = Integer.reverse(crc32); // result reflect
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return crc32 ^ 0xFFFFFFFF; // final xor value
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}
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}
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