Reads a decimal value as a IEEE-11073 32-bits float from ByteBuffer - Java Language Basics

Java examples for Language Basics:Bit

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Description

Reads a decimal value as a IEEE-11073 32-bits float from ByteBuffer

Demo Code

/***************************** BEGIN LICENSE BLOCK ***************************

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If a copy of the MPL was not distributed with this file, You can obtain one
at http://mozilla.org/MPL/2.0/./* w ww.ja  v  a2s.c om*/

Software distributed under the License is distributed on an "AS IS" basis,
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//package com.java2s;
import java.nio.ByteBuffer;

public class Main {
    /** 
     * Reads a decimal value as a IEEE-11073 32-bits float
     * This is necessary because the default float format in java is IEEE-754
     * @param data byte buffer to read the 4 bytes from
     * @return java float value decoded from the given bytes
     **/
    public static float readHealthFloat32(ByteBuffer data) {
        byte b0 = data.get();
        byte b1 = data.get();
        byte b2 = data.get();
        byte b3 = data.get();
        int mantissa = unsignedToSigned((b0 & 0xFF) + ((b1 & 0xFF) << 8)
                + ((b2 & 0xFF) << 16), 24);
        return (float) (mantissa * Math.pow(10, b3));
    }

    private static int unsignedToSigned(int unsigned, int size) {
        if ((unsigned & (1 << size - 1)) != 0)
            unsigned = -1
                    * ((1 << size - 1) - (unsigned & ((1 << size - 1) - 1)));
        return unsigned;
    }
}

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