/**************************************************************************
* Author: Isai Damier
* Title: Reverse Bits of Short (16-bit)
* Project: geekviewpoint
* Package: algorithms
*
* Statement:
* Given an integer, reverse its bit sequence.
*
* Sample Input: 0000000100100110
* Sample Output: 0110010010000000
*
* Technical Details:
* It is necessary to know whether the decimal number being passed as
* input is of type byte (8-bit) or short (16-bit) or int (32-bit) or
* long (64-bit): because Java will discard leading zeroes. For instance,
* if x = 0011010, Java will trim it to 11010 and then cause the reverse
* to look like 1011. Under such circumstances the reverseBits operation
* would not be reversible.
*
* To keep things simple, the presented algorithm treats short (16-bit)
* inputs.
**************************************************************************/
public short reverseBitsShort(short x) {
int intSize = 16;
short y=0;
for(int position=intSize-1; position>0; position--){
y+=((x&1)<<position);
x >>= 1;
}
return y;
}
import org.junit.Test;
import static org.junit.Assert.*;
public class BitwiseTest {
/**
* Test of reverseBitsShort method, of class Bitwise.
*/
@Test
public void testReverseBitsShort() {
System.out.println(""reverseBits"");
String a = ""0000000100100110"";
String b = ""0110010010000000"";
short x = Short.parseShort(a,2);
short r = Short.parseShort(b,2);
Bitwise bits = new Bitwise();
assertEquals(r, bits.reverseBitsShort(x));
assertEquals(x, bits.reverseBitsShort(r));
}
}