34 lines
1.3 KiB
Java
34 lines
1.3 KiB
Java
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package zutil;
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/**
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* Utility functions for byte primitive type
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*
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* Created by Ziver on 2016-01-30.
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*/
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public class ByteUtil {
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private static final int[][] BYTE_MASK = new int[][]{
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{0b0000_0001},
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{0b0000_0010, 0b0000_0011},
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{0b0000_0100, 0b0000_0110, 0b0000_0111},
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{0b0000_1000, 0b0000_1100, 0b0000_1110, 0b0000_1111},
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{0b0001_0000, 0b0001_1000, 0b0001_1100, 0b0001_1110, 0b0001_1111},
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{0b0010_0000, 0b0011_0000, 0b0011_1000, 0b0011_1100, 0b0011_1110, 0b0011_1111},
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{0b0100_0000, 0b0110_0000, 0b0111_0000, 0b0111_1000, 0b0111_1100, 0b0111_1110, 0b0111_1111},
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{0b1000_0000, 0b1100_0000, 0b1110_0000, 0b1111_0000, 0b1111_1000, 0b1111_1100, 0b1111_1110, 0b1111_1111}
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};
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public static byte getBits(byte data, int index, int length){
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length--;
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if(0 > index || index > 7)
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throw new IllegalArgumentException("Invalid index argument, allowed value is 0-7");
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if(length < 0 && index-length < 0)
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throw new IllegalArgumentException("Invalid length argument: "+length+", allowed values 1-8 depending on index");
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int ret = data & BYTE_MASK[index][length];
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ret = ret >>> index-length;
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return (byte) ret;
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}
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}
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