1 /*
   2  * Copyright (c) 2007, 2013, Oracle and/or its affiliates. All rights reserved.
   3  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
   4  *
   5  * This code is free software; you can redistribute it and/or modify it
   6  * under the terms of the GNU General Public License version 2 only, as
   7  * published by the Free Software Foundation.  Oracle designates this
   8  * particular file as subject to the "Classpath" exception as provided
   9  * by Oracle in the LICENSE file that accompanied this code.
  10  *
  11  * This code is distributed in the hope that it will be useful, but WITHOUT
  12  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  13  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  14  * version 2 for more details (a copy is included in the LICENSE file that
  15  * accompanied this code).
  16  *
  17  * You should have received a copy of the GNU General Public License version
  18  * 2 along with this work; if not, write to the Free Software Foundation,
  19  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
  20  *
  21  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
  22  * or visit www.oracle.com if you need additional information or have any
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  24  */
  25 package com.sun.media.sound;
  26 
  27 /**
  28  * A resampler that uses first-order (linear) interpolation.
  29  *
  30  * This one doesn't perform float to int casting inside the processing loop.
  31  *
  32  * @author Karl Helgason
  33  */
  34 public final class SoftLinearResampler2 extends SoftAbstractResampler {
  35 
  36     @Override
  37     public int getPadding() {
  38         return 2;
  39     }
  40 
  41     @Override
  42     public void interpolate(float[] in, float[] in_offset, float in_end,
  43                             float[] startpitch, float pitchstep, float[] out, int[] out_offset,
  44                             int out_end) {
  45 
  46         float pitch = startpitch[0];
  47         float ix = in_offset[0];
  48         int ox = out_offset[0];
  49         float ix_end = in_end;
  50         int ox_end = out_end;
  51 
  52         // Check if we have do anything
  53         if (!(ix < ix_end && ox < ox_end))
  54             return;
  55 
  56         // 15 bit shift was choosed because
  57         // it resulted in no drift between p_ix and ix.
  58         int p_ix = (int) (ix * (1 << 15));
  59         int p_ix_end = (int) (ix_end * (1 << 15));
  60         int p_pitch = (int) (pitch * (1 << 15));
  61         // Pitch needs to recalculated
  62         // to ensure no drift between p_ix and ix.
  63         pitch = p_pitch * (1f / (1 << 15));
  64 
  65         if (pitchstep == 0f) {
  66 
  67             // To reduce
  68             //    while (p_ix < p_ix_end && ox < ox_end)
  69             // into
  70             //    while  (ox < ox_end)
  71             // We need to calculate new ox_end value.
  72             int p_ix_len = p_ix_end - p_ix;
  73             int p_mod = p_ix_len % p_pitch;
  74             if (p_mod != 0)
  75                 p_ix_len += p_pitch - p_mod;
  76             int ox_end2 = ox + p_ix_len / p_pitch;
  77             if (ox_end2 < ox_end)
  78                 ox_end = ox_end2;
  79 
  80             while (ox < ox_end) {
  81                 int iix = p_ix >> 15;
  82                 float fix = ix - iix;
  83                 float i = in[iix];
  84                 out[ox++] = i + (in[iix + 1] - i) * fix;
  85                 p_ix += p_pitch;
  86                 ix += pitch;
  87             }
  88 
  89         } else {
  90 
  91             int p_pitchstep = (int) (pitchstep * (1 << 15));
  92             pitchstep = p_pitchstep * (1f / (1 << 15));
  93 
  94             while (p_ix < p_ix_end && ox < ox_end) {
  95                 int iix = p_ix >> 15;
  96                 float fix = ix - iix;
  97                 float i = in[iix];
  98                 out[ox++] = i + (in[iix + 1] - i) * fix;
  99                 ix += pitch;
 100                 p_ix += p_pitch;
 101                 pitch += pitchstep;
 102                 p_pitch += p_pitchstep;
 103             }
 104         }
 105         in_offset[0] = ix;
 106         out_offset[0] = ox;
 107         startpitch[0] = pitch;
 108 
 109     }
 110 }