/*
   Copyright 2019 Jean Pierre Cimalando.

   Licensed under the Apache License, Version 2.0 (the "License");
   you may not use this file except in compliance with the License.
   You may obtain a copy of the License at

        http://www.apache.org/licenses/LICENSE-2.0

   Unless required by applicable law or agreed to in writing, software
   distributed under the License is distributed on an "AS IS" BASIS,
   WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
   See the License for the specific language governing permissions and
   limitations under the License.
*/

#include <math.h>
#include "porta.h"
#include "synth.h"

void Porta::init_sr(double sampleRate)
{
  // compute portamento for CC 7-bit range

  for (unsigned int i = 0; i < 128; ++i) {
    // number of semitones travelled
    double sps = 350.0 * pow(2.0, -0.062 * i);  // per second
    double spf = sps / sampleRate;              // per frame
    double spp = spf * _N_;                       // per period
    const int step = (1 << 24) / 12;
    rates[i] = (int32_t)(0.5f + step * spp);    // to pitch units
  }
}

int32_t Porta::rates[128];
