Bits.java

/*
 * @(#)Bits.java	1.8 06/10/10
 *
 * Copyright  1990-2008 Sun Microsystems, Inc. All Rights Reserved.  
 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER  
 *   
 * This program is free software; you can redistribute it and/or  
 * modify it under the terms of the GNU General Public License version  
 * 2 only, as published by the Free Software Foundation.   
 *   
 * This program is distributed in the hope that it will be useful, but  
 * WITHOUT ANY WARRANTY; without even the implied warranty of  
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU  
 * General Public License version 2 for more details (a copy is  
 * included at /legal/license.txt).   
 *   
 * You should have received a copy of the GNU General Public License  
 * version 2 along with this work; if not, write to the Free Software  
 * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  
 * 02110-1301 USA   
 *   
 * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa  
 * Clara, CA 95054 or visit www.sun.com if you need additional  
 * information or have any questions. 
 *
 */

// Copied from JDK 1.4 for serialization back-port.

package java.io;

/**
 * Utility methods for packing/unpacking primitive values in/out of byte arrays
 * using big-endian byte ordering.
 */
class Bits {
    
    /*
     * Methods for unpacking primitive values from byte arrays starting at
     * given offsets.
     */

    static boolean getBoolean(byte[] b, int off) {
	return b[off] != 0;
    }
    
    static char getChar(byte[] b, int off) {
	return (char) (((b[off + 1] & 0xFF) << 0) + 
		       ((b[off + 0] & 0xFF) << 8));
    }
    
    static short getShort(byte[] b, int off) {
	return (short) (((b[off + 1] & 0xFF) << 0) + 
			((b[off + 0] & 0xFF) << 8));
    }
    
    static int getInt(byte[] b, int off) {
	return ((b[off + 3] & 0xFF) << 0) +
	       ((b[off + 2] & 0xFF) << 8) +
	       ((b[off + 1] & 0xFF) << 16) +
	       ((b[off + 0] & 0xFF) << 24);
    }
    
    static float getFloat(byte[] b, int off) {
	int i = ((b[off + 3] & 0xFF) << 0) +
		((b[off + 2] & 0xFF) << 8) +
		((b[off + 1] & 0xFF) << 16) +
		((b[off + 0] & 0xFF) << 24);
	return Float.intBitsToFloat(i);
    }
    
    static long getLong(byte[] b, int off) {
	return ((b[off + 7] & 0xFFL) << 0) +
	       ((b[off + 6] & 0xFFL) << 8) +
	       ((b[off + 5] & 0xFFL) << 16) +
	       ((b[off + 4] & 0xFFL) << 24) +
	       ((b[off + 3] & 0xFFL) << 32) +
	       ((b[off + 2] & 0xFFL) << 40) +
	       ((b[off + 1] & 0xFFL) << 48) +
	       ((b[off + 0] & 0xFFL) << 56);
    }

    static double getDouble(byte[] b, int off) {
	long j = ((b[off + 7] & 0xFFL) << 0) +
		 ((b[off + 6] & 0xFFL) << 8) +
		 ((b[off + 5] & 0xFFL) << 16) +
		 ((b[off + 4] & 0xFFL) << 24) +
		 ((b[off + 3] & 0xFFL) << 32) +
		 ((b[off + 2] & 0xFFL) << 40) +
		 ((b[off + 1] & 0xFFL) << 48) +
		 ((b[off + 0] & 0xFFL) << 56);
	return Double.longBitsToDouble(j);
    }
    
    /*
     * Methods for packing primitive values into byte arrays starting at given
     * offsets.
     */

    static void putBoolean(byte[] b, int off, boolean val) {
	b[off] = (byte) (val ? 1 : 0);
    }

    static void putChar(byte[] b, int off, char val) {
	b[off + 1] = (byte) (val >>> 0);
	b[off + 0] = (byte) (val >>> 8);
    }

    static void putShort(byte[] b, int off, short val) {
	b[off + 1] = (byte) (val >>> 0);
	b[off + 0] = (byte) (val >>> 8);
    }

    static void putInt(byte[] b, int off, int val) {
	b[off + 3] = (byte) (val >>> 0);
	b[off + 2] = (byte) (val >>> 8);
	b[off + 1] = (byte) (val >>> 16);
	b[off + 0] = (byte) (val >>> 24);
    }

    static void putFloat(byte[] b, int off, float val) {
	int i = Float.floatToIntBits(val);
	b[off + 3] = (byte) (i >>> 0);
	b[off + 2] = (byte) (i >>> 8);
	b[off + 1] = (byte) (i >>> 16);
	b[off + 0] = (byte) (i >>> 24);
    }

    static void putLong(byte[] b, int off, long val) {
	b[off + 7] = (byte) (val >>> 0);
	b[off + 6] = (byte) (val >>> 8);
	b[off + 5] = (byte) (val >>> 16);
	b[off + 4] = (byte) (val >>> 24);
	b[off + 3] = (byte) (val >>> 32);
	b[off + 2] = (byte) (val >>> 40);
	b[off + 1] = (byte) (val >>> 48);
	b[off + 0] = (byte) (val >>> 56);
    }

    static void putDouble(byte[] b, int off, double val) {
	long j = Double.doubleToLongBits(val);
	b[off + 7] = (byte) (j >>> 0);
	b[off + 6] = (byte) (j >>> 8);
	b[off + 5] = (byte) (j >>> 16);
	b[off + 4] = (byte) (j >>> 24);
	b[off + 3] = (byte) (j >>> 32);
	b[off + 2] = (byte) (j >>> 40);
	b[off + 1] = (byte) (j >>> 48);
	b[off + 0] = (byte) (j >>> 56);
    }
}