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+////////////////////////////////////////////////////////////////////////////////
+///
+/// Linear interpolation algorithm.
+///
+/// Author : Copyright (c) Olli Parviainen
+/// Author e-mail : oparviai 'at' iki.fi
+/// SoundTouch WWW: http://www.surina.net/soundtouch
+///
+////////////////////////////////////////////////////////////////////////////////
+//
+// $Id: InterpolateLinear.cpp 180 2014-01-06 19:16:02Z oparviai $
+//
+////////////////////////////////////////////////////////////////////////////////
+//
+// License :
+//
+// SoundTouch audio processing library
+// Copyright (c) Olli Parviainen
+//
+// This library is free software; you can redistribute it and/or
+// modify it under the terms of the GNU Lesser General Public
+// License as published by the Free Software Foundation; either
+// version 2.1 of the License, or (at your option) any later version.
+//
+// This library 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
+// Lesser General Public License for more details.
+//
+// You should have received a copy of the GNU Lesser General Public
+// License along with this library; if not, write to the Free Software
+// Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
+//
+////////////////////////////////////////////////////////////////////////////////
+
+#include <assert.h>
+#include <stdlib.h>
+#include "InterpolateLinear.h"
+
+using namespace soundtouch;
+
+//////////////////////////////////////////////////////////////////////////////
+//
+// InterpolateLinearInteger - integer arithmetic implementation
+//
+
+/// fixed-point interpolation routine precision
+#define SCALE 65536
+
+
+// Constructor
+InterpolateLinearInteger::InterpolateLinearInteger() : TransposerBase()
+{
+ // Notice: use local function calling syntax for sake of clarity,
+ // to indicate the fact that C++ constructor can't call virtual functions.
+ resetRegisters();
+ setRate(1.0f);
+}
+
+
+void InterpolateLinearInteger::resetRegisters()
+{
+ iFract = 0;
+}
+
+
+// Transposes the sample rate of the given samples using linear interpolation.
+// 'Mono' version of the routine. Returns the number of samples returned in
+// the "dest" buffer
+int InterpolateLinearInteger::transposeMono(SAMPLETYPE *dest, const SAMPLETYPE *src, int &srcSamples)
+{
+ int i;
+ int srcSampleEnd = srcSamples - 1;
+ int srcCount = 0;
+
+ i = 0;
+ while (srcCount < srcSampleEnd)
+ {
+ LONG_SAMPLETYPE temp;
+
+ assert(iFract < SCALE);
+
+ temp = (SCALE - iFract) * src[0] + iFract * src[1];
+ dest[i] = (SAMPLETYPE)(temp / SCALE);
+ i++;
+
+ iFract += iRate;
+
+ int iWhole = iFract / SCALE;
+ iFract -= iWhole * SCALE;
+ srcCount += iWhole;
+ src += iWhole;
+ }
+ srcSamples = srcCount;
+
+ return i;
+}
+
+
+// Transposes the sample rate of the given samples using linear interpolation.
+// 'Stereo' version of the routine. Returns the number of samples returned in
+// the "dest" buffer
+int InterpolateLinearInteger::transposeStereo(SAMPLETYPE *dest, const SAMPLETYPE *src, int &srcSamples)
+{
+ int i;
+ int srcSampleEnd = srcSamples - 1;
+ int srcCount = 0;
+
+ i = 0;
+ while (srcCount < srcSampleEnd)
+ {
+ LONG_SAMPLETYPE temp0;
+ LONG_SAMPLETYPE temp1;
+
+ assert(iFract < SCALE);
+
+ temp0 = (SCALE - iFract) * src[0] + iFract * src[2];
+ temp1 = (SCALE - iFract) * src[1] + iFract * src[3];
+ dest[0] = (SAMPLETYPE)(temp0 / SCALE);
+ dest[1] = (SAMPLETYPE)(temp1 / SCALE);
+ dest += 2;
+ i++;
+
+ iFract += iRate;
+
+ int iWhole = iFract / SCALE;
+ iFract -= iWhole * SCALE;
+ srcCount += iWhole;
+ src += 2*iWhole;
+ }
+ srcSamples = srcCount;
+
+ return i;
+}
+
+
+int InterpolateLinearInteger::transposeMulti(SAMPLETYPE *dest, const SAMPLETYPE *src, int &srcSamples)
+{
+ int i;
+ int srcSampleEnd = srcSamples - 1;
+ int srcCount = 0;
+
+ i = 0;
+ while (srcCount < srcSampleEnd)
+ {
+ LONG_SAMPLETYPE temp, vol1;
+
+ assert(iFract < SCALE);
+ vol1 = (SCALE - iFract);
+ for (int c = 0; c < numChannels; c ++)
+ {
+ temp = vol1 * src[c] + iFract * src[c + numChannels];
+ dest[0] = (SAMPLETYPE)(temp / SCALE);
+ dest ++;
+ }
+ i++;
+
+ iFract += iRate;
+
+ int iWhole = iFract / SCALE;
+ iFract -= iWhole * SCALE;
+ srcCount += iWhole;
+ src += iWhole * numChannels;
+ }
+ srcSamples = srcCount;
+
+ return i;
+}
+
+
+// Sets new target iRate. Normal iRate = 1.0, smaller values represent slower
+// iRate, larger faster iRates.
+void InterpolateLinearInteger::setRate(float newRate)
+{
+ iRate = (int)(newRate * SCALE + 0.5f);
+ TransposerBase::setRate(newRate);
+}
+
+
+//////////////////////////////////////////////////////////////////////////////
+//
+// InterpolateLinearFloat - floating point arithmetic implementation
+//
+//////////////////////////////////////////////////////////////////////////////
+
+
+// Constructor
+InterpolateLinearFloat::InterpolateLinearFloat() : TransposerBase()
+{
+ // Notice: use local function calling syntax for sake of clarity,
+ // to indicate the fact that C++ constructor can't call virtual functions.
+ resetRegisters();
+ setRate(1.0f);
+}
+
+
+void InterpolateLinearFloat::resetRegisters()
+{
+ fract = 0;
+}
+
+
+// Transposes the sample rate of the given samples using linear interpolation.
+// 'Mono' version of the routine. Returns the number of samples returned in
+// the "dest" buffer
+int InterpolateLinearFloat::transposeMono(SAMPLETYPE *dest, const SAMPLETYPE *src, int &srcSamples)
+{
+ int i;
+ int srcSampleEnd = srcSamples - 1;
+ int srcCount = 0;
+
+ i = 0;
+ while (srcCount < srcSampleEnd)
+ {
+ double out;
+ assert(fract < 1.0);
+
+ out = (1.0 - fract) * src[0] + fract * src[1];
+ dest[i] = (SAMPLETYPE)out;
+ i ++;
+
+ // update position fraction
+ fract += rate;
+ // update whole positions
+ int whole = (int)fract;
+ fract -= whole;
+ src += whole;
+ srcCount += whole;
+ }
+ srcSamples = srcCount;
+ return i;
+}
+
+
+// Transposes the sample rate of the given samples using linear interpolation.
+// 'Mono' version of the routine. Returns the number of samples returned in
+// the "dest" buffer
+int InterpolateLinearFloat::transposeStereo(SAMPLETYPE *dest, const SAMPLETYPE *src, int &srcSamples)
+{
+ int i;
+ int srcSampleEnd = srcSamples - 1;
+ int srcCount = 0;
+
+ i = 0;
+ while (srcCount < srcSampleEnd)
+ {
+ double out0, out1;
+ assert(fract < 1.0);
+
+ out0 = (1.0 - fract) * src[0] + fract * src[2];
+ out1 = (1.0 - fract) * src[1] + fract * src[3];
+ dest[2*i] = (SAMPLETYPE)out0;
+ dest[2*i+1] = (SAMPLETYPE)out1;
+ i ++;
+
+ // update position fraction
+ fract += rate;
+ // update whole positions
+ int whole = (int)fract;
+ fract -= whole;
+ src += 2*whole;
+ srcCount += whole;
+ }
+ srcSamples = srcCount;
+ return i;
+}
+
+
+int InterpolateLinearFloat::transposeMulti(SAMPLETYPE *dest, const SAMPLETYPE *src, int &srcSamples)
+{
+ int i;
+ int srcSampleEnd = srcSamples - 1;
+ int srcCount = 0;
+
+ i = 0;
+ while (srcCount < srcSampleEnd)
+ {
+ float temp, vol1;
+
+ vol1 = (1.0f- fract);
+ for (int c = 0; c < numChannels; c ++)
+ {
+ temp = vol1 * src[c] + fract * src[c + numChannels];
+ *dest = (SAMPLETYPE)temp;
+ dest ++;
+ }
+ i++;
+
+ fract += rate;
+
+ int iWhole = (int)fract;
+ fract -= iWhole;
+ srcCount += iWhole;
+ src += iWhole * numChannels;
+ }
+ srcSamples = srcCount;
+
+ return i;
+}
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