package zutil;

/**
 * Utility functions for byte primitive type
 *
 * Created by Ziver on 2016-01-30.
 */
public class ByteUtil {

    private static final int[][] BYTE_MASK = new int[][]{
            {0b0000_0001},
            {0b0000_0010, 0b0000_0011},
            {0b0000_0100, 0b0000_0110, 0b0000_0111},
            {0b0000_1000, 0b0000_1100, 0b0000_1110, 0b0000_1111},
            {0b0001_0000, 0b0001_1000, 0b0001_1100, 0b0001_1110, 0b0001_1111},
            {0b0010_0000, 0b0011_0000, 0b0011_1000, 0b0011_1100, 0b0011_1110, 0b0011_1111},
            {0b0100_0000, 0b0110_0000, 0b0111_0000, 0b0111_1000, 0b0111_1100, 0b0111_1110, 0b0111_1111},
            {0b1000_0000, 0b1100_0000, 0b1110_0000, 0b1111_0000, 0b1111_1000, 0b1111_1100, 0b1111_1110, 0b1111_1111}
    };

    public static byte getBits(byte data, int index, int length){
        length--;
        if(0 > index || index > 7)
            throw new IllegalArgumentException("Invalid index argument, allowed value is 0-7");
        if(length < 0 && index-length < 0)
            throw new IllegalArgumentException("Invalid length argument: "+length+", allowed values 1-8 depending on index");

        int ret = data & BYTE_MASK[index][length];
        ret = ret >>> index-length;
        return (byte) ret;
    }

}