/*
   Copyright 2012 Google Inc.

   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 "synth.h"
#include "pitchenv.h"

int PitchEnv::unit_;

void PitchEnv::init(FRAC_NUM sample_rate) {
  unit_ = _N_ * (1 << 24) / (21.3 * sample_rate) + 0.5;
}

const uint8_t pitchenv_rate[] = {
  1, 2, 3, 3, 4, 4, 5, 5, 6, 6, 7, 7, 8, 8, 9, 9, 10, 10, 11, 11, 12,
  12, 13, 13, 14, 14, 15, 16, 16, 17, 18, 18, 19, 20, 21, 22, 23, 24,
  25, 26, 27, 28, 30, 31, 33, 34, 36, 37, 38, 39, 41, 42, 44, 46, 47,
  49, 51, 53, 54, 56, 58, 60, 62, 64, 66, 68, 70, 72, 74, 76, 79, 82,
  85, 88, 91, 94, 98, 102, 106, 110, 115, 120, 125, 130, 135, 141, 147,
  153, 159, 165, 171, 178, 185, 193, 202, 211, 232, 243, 254, 255
};

const int8_t pitchenv_tab[] = {
  -128, -116, -104, -95, -85, -76, -68, -61, -56, -52, -49, -46, -43,
  -41, -39, -37, -35, -33, -32, -31, -30, -29, -28, -27, -26, -25, -24,
  -23, -22, -21, -20, -19, -18, -17, -16, -15, -14, -13, -12, -11, -10,
  -9, -8, -7, -6, -5, -4, -3, -2, -1, 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10,
  11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27,
  28, 29, 30, 31, 32, 33, 34, 35, 38, 40, 43, 46, 49, 53, 58, 65, 73,
  82, 92, 103, 115, 127
};

void PitchEnv::set(const int r[4], const int l[4]) {
  for (int i = 0; i < 4; i++) {
    rates_[i] = r[i];
    levels_[i] = l[i];
  }
  level_ = pitchenv_tab[l[3]] << 19;
  down_ = true;
  advance(0);
}

int32_t PitchEnv::getsample() {
  if (ix_ < 3 || ((ix_ < 4) && !down_)) {
    if (rising_) {
      level_ += inc_;
      if (level_ >= targetlevel_) {
        level_ = targetlevel_;
        advance(ix_ + 1);
      }
    } else {  // !rising
      level_ -= inc_;
      if (level_ <= targetlevel_) {
        level_ = targetlevel_;
        advance(ix_ + 1);
      }
    }
  }
  return level_;
}

void PitchEnv::keydown(bool d) {
  if (down_ != d) {
    down_ = d;
    advance(d ? 0 : 3);
  }
}

void PitchEnv::advance(int newix) {
  ix_ = newix;
  if (ix_ < 4) {
    int newlevel = levels_[ix_];
    targetlevel_ = pitchenv_tab[newlevel] << 19;
    rising_ = (targetlevel_ > level_);
    inc_ = pitchenv_rate[rates_[ix_]] * unit_;
  }
}

void PitchEnv::getPosition(char *step) {
  *step = ix_;
}