Conversion.java

/* 
 * Permission is hereby granted, free of charge, to any person obtaining a copy of 
 * this software and associated documentation files (the "Software"), to deal in 
 * the Software without restriction, including without limitation the rights to 
 * use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies 
 * of the Software, and to permit persons to whom the Software is furnished to do
 * so, subject to the following conditions:
 * 
 * The above copyright notice and this permission notice shall be included in all
 * copies or substantial portions of the Software.
 * 
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, 
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE 
 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER 
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, 
 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE 
 * SOFTWARE.
 */

package wombat.scheme.util;

/**
 * Source: http://svn.codehaus.org/jruby/jcodings/trunk/src/org/jcodings/util/ArrayCopy.java
 * Convert between int arrays and interspliced byte arrays. 
 */
public class Conversion {
	private Conversion() {}

	/**
	 * Convert byte arrays to int arrays.
	 * @param src Original byte array.
	 * @return Merge every four into an int for a new array.
	 */
	public static int[] byte2int(byte[] src) {
        int dstLength = src.length >>> 2;
        int[] dst = new int[dstLength];
        
        for (int i = 0; i < dstLength; i++) {
            int j = i << 2;
            int x = 0;
            x += (src[j++] & 0xff) << 0;
            x += (src[j++] & 0xff) << 8;
            x += (src[j++] & 0xff) << 16;
            x += (src[j++] & 0xff) << 24;
            dst[i] = x;
        }
        return dst;
    }
	
	/**
	 * Pull apart int arrays to a byte array.
	 * @param src The original int array.
	 * @return The returned byte.
	 */
	public static byte[] int2byte(int[] src) {
	    int srcLength = src.length;
	    byte[] dst = new byte[srcLength << 2];
	    
	    for (int i = 0; i < srcLength; i++) {
	        int x = src[i];
	        int j = i << 2;
	        dst[j++] = (byte) ((x >>> 0) & 0xff);           
	        dst[j++] = (byte) ((x >>> 8) & 0xff);
	        dst[j++] = (byte) ((x >>> 16) & 0xff);
	        dst[j++] = (byte) ((x >>> 24) & 0xff);
	    }
	    return dst;
	}
}