/*******************************************************************************
 * Copyright (c) 2013, Daniel Murphy
 * All rights reserved. 
 * 
 * Redistribution and use in source and binary forms, with or without modification,
 * are permitted provided that the following conditions are met:
 * 	* Redistributions of source code must retain the above copyright notice,
 * 	  this list of conditions and the following disclaimer. 
 * 	* Redistributions in binary form must reproduce the above copyright notice,
 * 	  this list of conditions and the following disclaimer in the documentation
 * 	  and/or other materials provided with the distribution. 
 * 
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
 * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. 
 * IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT,
 * INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
 * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
 * WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
 * POSSIBILITY OF SUCH DAMAGE. 
 ******************************************************************************/
package org.jbox2d.common;

/**
 * Contains methods from MathUtils that rely on JVM features.  These are separated out from
 * MathUtils so that they can be overridden when compiling for GWT. 
 */
class PlatformMathUtils {

  private static final float SHIFT23 = 1 << 23;
  private static final float INV_SHIFT23 = 1.0f / SHIFT23;

  public static final float fastPow(float a, float b) {
    float x = Float.floatToRawIntBits(a);
    x *= INV_SHIFT23;
    x -= 127;
    float y = x - (x >= 0 ? ( int) x : (int) x - 1);
    b *= x + (y - y * y) * 0.346607f;
    y = b - (b >= 0 ? ( int) b : (int) b - 1);
    y = (y - y * y) * 0.33971f;
    return Float.intBitsToFloat((int) ((b + 127 - y) * SHIFT23));
  }
}
