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35 lines
1.1 KiB
35 lines
1.1 KiB
/*
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Copyright 2019 Jean Pierre Cimalando.
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Licensed under the Apache License, Version 2.0 (the "License");
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you may not use this file except in compliance with the License.
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You may obtain a copy of the License at
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http://www.apache.org/licenses/LICENSE-2.0
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Unless required by applicable law or agreed to in writing, software
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distributed under the License is distributed on an "AS IS" BASIS,
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WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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See the License for the specific language governing permissions and
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limitations under the License.
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*/
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#include <math.h>
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#include "porta.h"
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#include "synth.h"
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void Porta::init_sr(double sampleRate)
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{
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// compute portamento for CC 7-bit range
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for (unsigned int i = 0; i < 128; ++i) {
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// number of semitones travelled
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double sps = 350.0 * pow(2.0, -0.062 * i); // per second
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double spf = sps / sampleRate; // per frame
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double spp = spf * _N_; // per period
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const int step = (1 << 24) / 12;
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rates[i] = (int32_t)(0.5f + step * spp); // to pitch units
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}
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}
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int32_t Porta::rates[128];
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