reverse bits done in (1 method)

Author: Ram swaroop

src/me/ramswaroop/bits/ReverseBits.java

@@ -0,0 +1,40 @@
+package me.ramswaroop.bits;
+
+/**
+ * Created by IntelliJ IDEA.
+ *
+ * @author: ramswaroop
+ * @date: 6/5/15
+ * @time: 4:26 PM
+ * @link http://stackoverflow.com/questions/746171/best-algorithm-for-bit-reversal-from-msb-lsb-to-lsb-msb-in-c
+ * @link http://graphics.stanford.edu/~seander/bithacks.html#BitReverseObvious
+ */
+public class ReverseBits {
+
+    public static int getNumberByReversingBits(int n) {
+        System.out.println(Integer.toBinaryString(n));
+
+        int m;
+        // assume 32-bit number
+        m = 0x55555555; // 1-bit swap
+        n = ((n & m) << 1) | ((n & ~m) >> 1);
+
+        m = 0x33333333; // 2-bits swap
+        n = ((n & m) << 2) | ((n & ~m) >> 2);
+
+        m = 0x0f0f0f0f; // 4-bits swap
+        n = ((n & m) << 4) | ((n & ~m) >> 4);
+
+        m = 0x00ff00ff; // 8-bits swap
+        n = ((n & m) << 8) | ((n & ~m) >> 8);
+
+        n = (n << 16) | (n >> 16); // 16-bits swap
+
+        System.out.println(Integer.toBinaryString(n));
+        return n;
+    }
+
+    public static void main(String a[]) {
+        System.out.println(getNumberByReversingBits(7));
+    }
+}

src/me/ramswaroop/bits/SubBit.java

@@ -15,14 +15,14 @@ public class SubBit {
      *
      * @param num
      * @param start > 0 and <= 32
-     * @param end > 0 and <= 32
+     * @param end   > 0 and <= 32
      * @return
      */
-    public static int getSubBits(int num, int start, int end) {
+    public static int getNumberFromSubBits(int num, int start, int end) {
         return num << (32 - end) >>> (start - end + 31); // more intuitive (start - 1 + 32 - end)
     }
 
     public static void main(String a[]) {
-        System.out.println(getSubBits(5, 1, 2));
+        System.out.println(getNumberFromSubBits(5, 1, 2));
     }
 }