pattern_generator.h

// Copyright 2011 Emilie Gillet.
//
// Author: Emilie Gillet (emilie.o.gillet@gmail.com)
//
// This program is free software: you can redistribute it and/or modify
// it under the terms of the GNU General Public License as published by
// the Free Software Foundation, either version 3 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 General Public License for more details.
// You should have received a copy of the GNU General Public License
// along with this program.  If not, see <http://www.gnu.org/licenses/>.
//
// -----------------------------------------------------------------------------
//
// Pattern generator.
//
// OUTPUT MODE  OUTPUT CLOCK  BIT7  BIT6  BIT5  BIT4  BIT3  BIT2  BIT1  BIT0
// DRUMS        FALSE          RND   CLK  HHAC  SDAC  BDAC    HH    SD    BD
// DRUMS        TRUE           RND   CLK   CLK   BAR   ACC    HH    SD    BD
// EUCLIDEAN    FALSE          RND   CLK  RST3  RST2  RST1  EUC3  EUC2  EUC1
// EUCLIDEAN    TRUE           RND   CLK   CLK  STEP   RST  EUC3  EUC2  EUC1

#ifndef GRIDS_PATTERN_GENERATOR_H_
#define GRIDS_PATTERN_GENERATOR_H_

#include <string.h>

#include "avrlib/base.h"
#include "avrlib/random.h"

#include "grids/hardware_config.h"

namespace grids {

const uint8_t kNumParts = 3;
const uint8_t kPulsesPerStep = 3;  // 24 ppqn ; 8 steps per quarter note.
const uint8_t kStepsPerPattern = 32;
const uint8_t kPulseDuration = 48;  // 48 ticks of the main clock, roughly 6ms (default is 8 ticks, 1ms)

struct DrumsSettings {
  uint8_t x;
  uint8_t y;
  uint8_t randomness;
};

struct PatternGeneratorSettings {
  union Options {
    DrumsSettings drums;
    uint8_t euclidean_length[kNumParts];
  } options;
  uint8_t density[kNumParts];
};

enum OutputMode {
  OUTPUT_MODE_EUCLIDEAN,
  OUTPUT_MODE_DRUMS
};

enum ClockResolution {
  CLOCK_RESOLUTION_4_PPQN,
  CLOCK_RESOLUTION_8_PPQN,
  CLOCK_RESOLUTION_24_PPQN,
  CLOCK_RESOLUTION_LAST
};

enum OutputBits {
  OUTPUT_BIT_COMMON = 0x08,
  OUTPUT_BIT_CLOCK = 0x10,
  OUTPUT_BIT_RESET = 0x20
};

struct Options {
  ClockResolution clock_resolution;
  OutputMode output_mode;
  bool output_clock;
  bool tap_tempo;
  bool gate_mode;
  bool swing;
  
  uint8_t pack() const {
    uint8_t byte = clock_resolution;
    if (!swing) {
      byte |= 0x08;
    }
    if (tap_tempo) {
      byte |= 0x10;
    }
    if (output_clock) {
      byte |= 0x20;
    }
    if (output_mode == OUTPUT_MODE_DRUMS) {
      byte |= 0x40;
    }
    if (!gate_mode) {
      byte |= 0x80;
    }
    return byte;
  }
  
  void unpack(uint8_t byte) {
    tap_tempo = byte & 0x10;
    output_clock = byte & 0x20;
    output_mode = byte & 0x40 ? OUTPUT_MODE_DRUMS : OUTPUT_MODE_EUCLIDEAN;
    gate_mode = !(byte & 0x80);
    swing = !(byte & 0x08);
    clock_resolution = static_cast<ClockResolution>(byte & 0x7);
    if (clock_resolution >= CLOCK_RESOLUTION_24_PPQN) {
      clock_resolution = CLOCK_RESOLUTION_24_PPQN;
    }
  }
};

class PatternGenerator {
 public:
  PatternGenerator() { }
  ~PatternGenerator() { }
  
  static inline void Init() {
    LoadSettings();
    Reset();
  }

  static inline void Reset() {
    step_ = 0;
    pulse_ = 0;
    memset(euclidean_step_, 0, sizeof(euclidean_step_));
  }
  
  static inline void Retrigger() {
    Evaluate();
  }
  
  static inline void TickClock(uint8_t num_pulses) {
    Evaluate();
    beat_ = (step_ & 0x7) == 0;
    first_beat_ = step_ == 0;
    
    pulse_ += num_pulses;
    
    // Wrap into ppqn steps.
    while (pulse_ >= kPulsesPerStep) {
      pulse_ -= kPulsesPerStep;
      if (!(step_ & 1)) {
        for (uint8_t i = 0; i < kNumParts; ++i) {
          ++euclidean_step_[i];
        }
      }
      ++step_;
    }
    
    // Wrap into step sequence steps.
    if (step_ >= kStepsPerPattern) {
      step_ -= kStepsPerPattern;
    }
  }
  
  static inline uint8_t state() {
    return state_;
  }
  static inline uint8_t step() { return step_; }
  
  static inline bool swing() { return options_.swing; }
  static int8_t swing_amount();
  static inline bool output_clock() { return options_.output_clock; }
  static inline bool tap_tempo() { return options_.tap_tempo; }
  static inline bool gate_mode() { return options_.gate_mode; }
  static inline OutputMode output_mode() { return options_.output_mode; }
  static inline ClockResolution clock_resolution() { return options_.clock_resolution; }

  static void set_swing(uint8_t value) { options_.swing = value; }  
  static void set_output_clock(uint8_t value) { options_.output_clock = value; }
  static void set_tap_tempo(uint8_t value) { options_.tap_tempo = value; }
  static void set_output_mode(uint8_t value) { 
    options_.output_mode = static_cast<OutputMode>(value);
  }
  static void set_clock_resolution(uint8_t value) {
    if (value >= CLOCK_RESOLUTION_24_PPQN) {
      value = CLOCK_RESOLUTION_24_PPQN;
    }
    options_.clock_resolution = static_cast<ClockResolution>(value);
  }
  static void set_gate_mode(bool gate_mode) {
    options_.gate_mode = gate_mode;
  }
  
  static inline void IncrementPulseCounter() {
    ++pulse_duration_counter_;
    // Zero all pulses after 1ms.
    if (pulse_duration_counter_ >= kPulseDuration && !options_.gate_mode) {
      state_ = 0;
      // Possible mod: the extra random pulse is not reset, and its behaviour
      // is more similar to that of a S&H.
      //state_ &= 0x80;
    }
  }
  
  static inline void ClockFallingEdge() {
    if (options_.gate_mode) {
      state_ = 0;
    }
  }
  
  static inline PatternGeneratorSettings* mutable_settings() {
    return &settings_;
  }
  
  static bool on_first_beat() { return first_beat_; }
  static bool on_beat() { return beat_; }
  static bool factory_testing() { return factory_testing_ < 5; }

  static void SaveSettings();
  
  static inline uint8_t led_pattern() {
    uint8_t result = 0;
    if (state_ & 1) {
      result |= LED_BD;
    }
    if (state_ & 2) {
      result |= LED_SD;
    }
    if (state_ & 4) {
      result |= LED_HH;
    }
    return result;
  }
  
 private:
  static void LoadSettings();
  static void Evaluate();
  static void EvaluateEuclidean();
  static void EvaluateDrums();
  
  static uint8_t ReadDrumMap(
      uint8_t step,
      uint8_t instrument,
      uint8_t x,
      uint8_t y);

  static Options options_;
  
  static uint8_t pulse_;
  static uint8_t step_;
  static uint8_t euclidean_step_[kNumParts];
  static bool first_beat_;
  static bool beat_;
  
  static uint8_t state_;
  static uint8_t part_perturbation_[kNumParts];

  static uint8_t pulse_duration_counter_;
  
  static uint8_t factory_testing_;
  
  static PatternGeneratorSettings settings_;
  
  DISALLOW_COPY_AND_ASSIGN(PatternGenerator);
};

extern PatternGenerator pattern_generator;

}  // namespace grids

#endif // GRIDS_PATTERN_GENERATOR_H_