1 files changed, 75 insertions, 0 deletions
diff --git a/src/main/java/org/uic/barcode/asn1/uper/AsnUtils.java b/src/main/java/org/uic/barcode/asn1/uper/AsnUtils.java
new file mode 100644
index 0000000..414f181
--- /dev/null
+++ b/src/main/java/org/uic/barcode/asn1/uper/AsnUtils.java
@@ -0,0 +1,75 @@
+package org.uic.barcode.asn1.uper;
+
+import java.math.BigInteger;
+
+public class AsnUtils {
+	
+
+    private static byte[] mask = new byte[] {
+    	     (byte) 0b1000_0000,
+    	            0b0100_0000,
+    	            0b0010_0000,
+    	            0b0001_0000,
+    	            0b0000_1000,
+    	            0b0000_0100,
+    	            0b0000_0010,
+    	            0b0000_0001,
+    	    };
+    
+    
+	public static byte[] fromBooleanString(final String s) {
+		
+		char[] ascii = s.toCharArray();
+        if (ascii == null || ascii.length == 0) {
+            return null;
+        }
+        // get length/8 times bytes with 3 bit shifts to the right of the length
+        final byte[] l_raw = new byte[ascii.length >> 3];
+        /*
+         * We decr index jj by 8 as we go along to not recompute indices using multiplication every time inside the
+         * loop.
+         */
+        for (int ii = 0, jj = 0; ii < l_raw.length; ii++, jj += 8) {
+            for (int bits = 0; bits < mask.length; ++bits) {
+                if (ascii[jj + bits] == '1') {
+                    l_raw[ii] |= mask[bits];
+                }
+            }
+        }
+        return l_raw;
+    }
+	
+	public static String toBooleanString(byte[] bytes) {
+	        StringBuilder sb = new StringBuilder(bytes.length);
+	        for (int i = 0; i < bytes.length*8;i++) {
+	            sb.append(AsnUtils.get(bytes,i) ? "1" : "0");
+	        }
+	        return sb.toString();
+	}
+	
+	public static boolean get(byte[] bytes, int index) {
+	        
+		if (index < 0) {
+	            throw new IndexOutOfBoundsException("Index " + index + " is less than 0");
+	    } else if (index >= bytes.length * 8) {
+	            throw new IndexOutOfBoundsException("Index " + index + " violates the limit " + bytes.length*8);
+	    }
+	    boolean result = (bytes[index / 8] & mask[index % 8]) != 0;
+	    return result;
+	}
+	
+	public static byte[] shiftBytesToLeft(byte[] bytes, int shift) {
+		
+		// create from array
+		BigInteger bigInt = new BigInteger(bytes);
+
+		// shift
+		BigInteger shiftInt = bigInt.shiftLeft(shift);
+
+		// back to array
+		return shiftInt.toByteArray();
+
+	}
+	
+
+}