crc32 implementation

Pusty · web-flow · commit f2bfa6a1be8c · 2017-10-03T03:57:28.000+02:00
diff --git a/Misc/crc32.java b/Misc/crc32.java
@@ -0,0 +1,28 @@
+import java.util.BitSet;
+
+//Generates a crc32 checksum for a given string or byte array
+public class crc32 {
+    
+    public static void main(String[] args) {
+        System.out.println(Integer.toHexString(crc32("Hello World")));
+    }
+    
+    public static int crc32(String str) {
+        return crc32(str.getBytes());
+    }
+    
+    public static int crc32(byte[] data) {
+        BitSet bitSet = BitSet.valueOf(data);
+        int crc32 = 0xFFFFFFFF;                           //initial value
+        for(int i=0;i<data.length*8;i++) {
+            if(((crc32>>>31)&1) != (bitSet.get(i)?1:0))
+                crc32 = (crc32 << 1) ^ 0x04C11DB7;        //xoring with polynomial
+            else
+                crc32 = (crc32 << 1);
+        }
+        crc32 = crc32 ^ 0;
+        crc32 = Integer.reverse(crc32);                   //result reflect
+        return crc32 ^ 0xFFFFFFFF;                        //final xor value
+    }
+
+}
