high_hat.cc
// Copyright 2013 Olivier Gillet.
//
// Author: Olivier Gillet (ol.gillet@gmail.com)
//
// Permission is hereby granted, free of charge, to any person obtaining a copy
// of this software and associated documentation files (the "Software"), to deal
// in the Software without restriction, including without limitation the rights
// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
// copies of the Software, and to permit persons to whom the Software is
// furnished to do so, subject to the following conditions:
// 
// The above copyright notice and this permission notice shall be included in
// all copies or substantial portions of the Software.
// 
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
// THE SOFTWARE.
// 
// See http://creativecommons.org/licenses/MIT/ for more information.
//
// -----------------------------------------------------------------------------
//
// 808-style HH.

#include "peaks/drums/high_hat.h"

#include <cstdio>

#include "stmlib/utils/dsp.h"
#include "stmlib/utils/random.h"

#include "peaks/resources.h"

namespace peaks {

using namespace stmlib;

void HighHat::Init() {
  noise_.Init();
  noise_.set_frequency(105 << 7);  // 8kHz
  noise_.set_resonance(24000);
  
  vca_coloration_.Init();
  vca_coloration_.set_frequency(110 << 7);  // 13kHz
  vca_coloration_.set_resonance(0);
  
  vca_envelope_.Init();
  vca_envelope_.set_delay(0);
  vca_envelope_.set_decay(4093);
}

void HighHat::Process(const GateFlags* gate_flags, int16_t* out, size_t size) {
  while (size--) {
    GateFlags gate_flag = *gate_flags++;
    if (gate_flag & GATE_FLAG_RISING) {
      vca_envelope_.Trigger(32768 * 15);
    }
  
    phase_[0] += 48318382;
    phase_[1] += 71582788;
    phase_[2] += 37044092;
    phase_[3] += 54313440;
    phase_[4] += 66214079;
    phase_[5] += 93952409;

    int16_t noise = 0;
    noise += phase_[0] >> 31;
    noise += phase_[1] >> 31;
    noise += phase_[2] >> 31;
    noise += phase_[3] >> 31;
    noise += phase_[4] >> 31;
    noise += phase_[5] >> 31;
    noise <<= 12;
  
    // Run the SVF at the double of the original sample rate for stability.
    int32_t filtered_noise = 0;
    filtered_noise += noise_.Process<SVF_MODE_BP>(noise);
    filtered_noise += noise_.Process<SVF_MODE_BP>(noise);

    // The 808-style VCA amplifies only the positive section of the signal.
    if (filtered_noise < 0) {
      filtered_noise = 0;
    } else if (filtered_noise > 32767) {
      filtered_noise = 32767;
    }
  
    int32_t envelope = vca_envelope_.Process() >> 4;
    int32_t vca_noise = envelope * filtered_noise >> 14;
    CLIP(vca_noise);
    int32_t hh = 0;
    hh += vca_coloration_.Process<SVF_MODE_HP>(vca_noise);
    hh += vca_coloration_.Process<SVF_MODE_HP>(vca_noise);
    hh <<= 1;
    CLIP(hh);
    *out++ = hh;
  }
}

}  // namespace peaks