1 files changed, 47 insertions, 0 deletions
diff --git a/audio/softsynth/mt32/srchelper/srctools/src/LinearResampler.cpp b/audio/softsynth/mt32/srchelper/srctools/src/LinearResampler.cpp
new file mode 100644
index 0000000000..98b9c77c73
--- /dev/null
+++ b/audio/softsynth/mt32/srchelper/srctools/src/LinearResampler.cpp
@@ -0,0 +1,47 @@
+/* Copyright (C) 2015-2017 Sergey V. Mikayev
+ *
+ *  This program 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 program 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 program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#include "LinearResampler.h"
+
+using namespace SRCTools;
+
+LinearResampler::LinearResampler(double sourceSampleRate, double targetSampleRate) :
+	inputToOutputRatio(sourceSampleRate / targetSampleRate),
+	position(1.0) // Preload delay line which effectively makes resampler zero phase
+{}
+
+void LinearResampler::process(const FloatSample *&inSamples, unsigned int &inLength, FloatSample *&outSamples, unsigned int &outLength) {
+	if (inLength == 0) return;
+	while (outLength > 0) {
+		while (1.0 <= position) {
+			position--;
+			inLength--;
+			for (unsigned int chIx = 0; chIx < LINEAR_RESAMPER_CHANNEL_COUNT; ++chIx) {
+				lastInputSamples[chIx] = *(inSamples++);
+			}
+			if (inLength == 0) return;
+		}
+		for (unsigned int chIx = 0; chIx < LINEAR_RESAMPER_CHANNEL_COUNT; chIx++) {
+			*(outSamples++) = FloatSample(lastInputSamples[chIx] + position * (inSamples[chIx] - lastInputSamples[chIx]));
+		}
+		outLength--;
+		position += inputToOutputRatio;
+	}
+}
+
+unsigned int LinearResampler::estimateInLength(const unsigned int outLength) const {
+	return static_cast<unsigned int>(outLength * inputToOutputRatio);
+}