/*
 * Copyright 2007 Sun Microsystems, Inc.  All Rights Reserved.
 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
 *
 * This code 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.  Sun designates this
 * particular file as subject to the "Classpath" exception as provided
 * by Sun in the LICENSE file that accompanied this code.
 *
 * This code 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 in the LICENSE file that
 * accompanied this code).
 *
 * 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 USA or visit www.sun.com if you need additional information or
 * have any questions.
 */

package com.sun.media.sound;

/**
 * 
 * A resampler that uses first-order (linear) interpolation.
 * 
 * This one doesn't perform float to int casting
 * inside the processing loop.
 * 
 * @version %I%, %E%
 * @author Karl Helgason
 */
public class SoftLinearResampler2 extends SoftAbstractResampler {

	public int getPadding() {
		return 2;
	}
	
	public void interpolate(float[] in, float[] in_offset, float in_end,
			float[] startpitch, float pitchstep, float[] out, int[] out_offset,
			int out_end) {
		
 		float pitch = startpitch[0];
		float ix = in_offset[0];
		int ox = out_offset[0];
		float ix_end = in_end;
		int ox_end = out_end;
		
		// Check if we have do anything		
		if(!(ix < ix_end && ox < ox_end)) return;

		// 15 bit shift was choosed because
		// it resulted in no drift between p_ix and ix.
		int p_ix = (int)(ix * (1 << 15));
		int p_ix_end = (int)(ix_end * (1 << 15));
		int p_pitch = (int)(pitch * (1 << 15));
		// Pitch needs to recalculated
		// to ensure no drift between p_ix and ix.
		pitch = p_pitch * (1f/(1 << 15)); 
		
		if (pitchstep == 0f) {			
						
			// To reduce
			//    while (p_ix < p_ix_end && ox < ox_end)
			// into
			//    while  (ox < ox_end)
			// We need to calculate new ox_end value.
			int p_ix_len = p_ix_end - p_ix;
			int p_mod = p_ix_len % p_pitch;
			if(p_mod != 0) p_ix_len += p_pitch - p_mod;
			int ox_end2 = ox + p_ix_len/p_pitch;
			if(ox_end2 < ox_end) ox_end = ox_end2;
			
			while (ox < ox_end) {			
				int iix = p_ix >> 15;
				float fix = ix - iix;
				float i = in[iix];
				out[ox++] = i + (in[iix + 1] - i) * fix;								
				p_ix += p_pitch;
				ix += pitch;
			}	
			  
		} else {
			
			int p_pitchstep = (int)(pitchstep * (1 << 15)); 
			pitchstep = p_pitchstep * (1f/(1 << 15));
			
			while (p_ix < p_ix_end && ox < ox_end) {
				int iix = p_ix >> 15;
				float fix = ix - iix;
				float i = in[iix];
				out[ox++] = i + (in[iix + 1] - i) * fix;				
				ix += pitch;
				p_ix += p_pitch;
				pitch += pitchstep;
				p_pitch += p_pitchstep;
			}
		}
		in_offset[0] = ix;
		out_offset[0] = ox;
		startpitch[0] = pitch;

	}

}