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From: grkvlt <git@git.apache.org>
To: dev@brooklyn.apache.org
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References: <git-pr-494-brooklyn-server@git.apache.org>
In-Reply-To: <git-pr-494-brooklyn-server@git.apache.org>
Subject: [GitHub] brooklyn-server pull request #494: Simplify BitUtils methods
Content-Type: text/plain
Message-Id: <20170109105705.2FC9DDFB6E@git1-us-west.apache.org>
Date: Mon,  9 Jan 2017 10:57:05 +0000 (UTC)
archived-at: Mon, 09 Jan 2017 10:57:07 -0000

Github user grkvlt commented on a diff in the pull request:

    https://github.com/apache/brooklyn-server/pull/494#discussion_r95134861
  
    --- Diff: utils/common/src/main/java/org/apache/brooklyn/util/math/BitUtils.java ---
    @@ -18,25 +18,22 @@
      */
     package org.apache.brooklyn.util.math;
     
    +import com.google.common.primitives.Bytes;
    +import com.google.common.primitives.Ints;
    +
     public class BitUtils {
     
         /** reverses the bits in a byte, i.e.  128 = 0b1000000 = bit list {0,0,0,0,0,0,0,1},
          * reversed yields 1 = 0b00000001 = bit list {1,0,0,0,0,0,0,0} */
         public static byte reverseBitSignificance(byte b) {
    -        int result = 0;
    -        for (int i=0; i<8; i++) {
    -            result <<= 1;
    -            if ((b&1)==1) result++;
    -            b >>= 1;
    -        }
    -        return (byte)result;
    +        return (byte) (Integer.reverse(b) >> 24);
    --- End diff --
    
    No. The following tests should convince you:
    ```
            Assert.assertEquals(BitUtils.reverseBitSignificanceInByte(0b00000001), (byte)0b10000000);
            Assert.assertEquals(BitUtils.reverseBitSignificanceInByte(0x0f), (byte)0xf0);
    ```


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