pattern_generator.cc
// Copyright 2011 Olivier Gillet.
//
// Author: Olivier Gillet (ol.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/>.
//
// -----------------------------------------------------------------------------
//
// Global clock.

#include "grids/pattern_generator.h"

#include <avr/eeprom.h>
#include <avr/pgmspace.h>

#include "avrlib/op.h"

#include "grids/resources.h"

namespace grids {
  
using namespace avrlib;

/* static */
Options PatternGenerator::options_;

/* static */
uint8_t PatternGenerator::pulse_;

/* static */
uint8_t PatternGenerator::step_;

/* static */
bool PatternGenerator::first_beat_;

/* static */
bool PatternGenerator::beat_;

/* static */
uint8_t PatternGenerator::euclidean_step_[kNumParts];

/* static */
uint8_t PatternGenerator::state_;

/* static */
uint8_t PatternGenerator::pulse_duration_counter_;

/* static */
uint8_t PatternGenerator::part_perturbation_[kNumParts];

/* static */
PatternGeneratorSettings PatternGenerator::settings_;

/* static */
uint8_t PatternGenerator::factory_testing_;

/* extern */
PatternGenerator pattern_generator;

static const prog_uint8_t* drum_map[5][5] = {
  { node_10, node_8, node_0, node_9, node_11 },
  { node_15, node_7, node_13, node_12, node_6 },
  { node_18, node_14, node_4, node_5, node_3 },
  { node_23, node_16, node_21, node_1, node_2 },
  { node_24, node_19, node_17, node_20, node_22 },
};

/* static */
uint8_t PatternGenerator::ReadDrumMap(
    uint8_t step,
    uint8_t instrument,
    uint8_t x,
    uint8_t y) {
  uint8_t i = x >> 6;
  uint8_t j = y >> 6;
  const prog_uint8_t* a_map = drum_map[i][j];
  const prog_uint8_t* b_map = drum_map[i + 1][j];
  const prog_uint8_t* c_map = drum_map[i][j + 1];
  const prog_uint8_t* d_map = drum_map[i + 1][j + 1];
  uint8_t offset = (instrument * kStepsPerPattern) + step;
  uint8_t a = pgm_read_byte(a_map + offset);
  uint8_t b = pgm_read_byte(b_map + offset);
  uint8_t c = pgm_read_byte(c_map + offset);
  uint8_t d = pgm_read_byte(d_map + offset);
  return U8Mix(U8Mix(a, b, x << 2), U8Mix(c, d, x << 2), y << 2);
}

/* static */
void PatternGenerator::EvaluateDrums() {
  // At the beginning of a pattern, decide on perturbation levels.
  if (step_ == 0) {
    for (uint8_t i = 0; i < kNumParts; ++i) {
      uint8_t randomness = options_.swing
          ? 0 : settings_.options.drums.randomness >> 2;
      part_perturbation_[i] = U8U8MulShift8(Random::GetByte(), randomness);
    }
  }
  
  uint8_t instrument_mask = 1;
  uint8_t x = settings_.options.drums.x;
  uint8_t y = settings_.options.drums.y;
  uint8_t accent_bits = 0;
  for (uint8_t i = 0; i < kNumParts; ++i) {
    uint8_t level = ReadDrumMap(step_, i, x, y);
    if (level < 255 - part_perturbation_[i]) {
      level += part_perturbation_[i];
    } else {
      // The sequencer from Anushri uses a weird clipping rule here. Comment
      // this line to reproduce its behavior.
      level = 255;
    }
    uint8_t threshold = ~settings_.density[i];
    if (level > threshold) {
      if (level > 192) {
        accent_bits |= instrument_mask;
      }
      state_ |= instrument_mask;
    }
    instrument_mask <<= 1;
  }
  if (output_clock()) {
    state_ |= accent_bits ? OUTPUT_BIT_COMMON : 0;
    state_ |= step_ == 0 ? OUTPUT_BIT_RESET : 0;
  } else {
    state_ |= accent_bits << 3;
  }
}

/* static */
void PatternGenerator::EvaluateEuclidean() {
  // Refresh only on sixteenth notes.
  if (step_ & 1) {
    return;
  }
  
  // Euclidean pattern generation
  uint8_t instrument_mask = 1;
  uint8_t reset_bits = 0;
  for (uint8_t i = 0; i < kNumParts; ++i) {
    uint8_t length = (settings_.options.euclidean_length[i] >> 3) + 1;
    uint8_t density = settings_.density[i] >> 3;
    uint16_t address = U8U8Mul(length - 1, 32) + density;
    while (euclidean_step_[i] >= length) {
      euclidean_step_[i] -= length;
    }
    uint32_t step_mask = 1L << static_cast<uint32_t>(euclidean_step_[i]);
    uint32_t pattern_bits = pgm_read_dword(lut_res_euclidean + address);
    if (pattern_bits & step_mask) {
      state_ |= instrument_mask;
    }
    if (euclidean_step_[i] == 0) {
      reset_bits |= instrument_mask;
    }
    instrument_mask <<= 1;
  }
  
  if (output_clock()) {
    state_ |= reset_bits ? OUTPUT_BIT_COMMON : 0;
    state_ |= (reset_bits == 0x07) ? OUTPUT_BIT_RESET : 0;
  } else {
    state_ |= reset_bits << 3;
  }
}

/* static */
void PatternGenerator::LoadSettings() {
  options_.unpack(eeprom_read_byte(NULL));
  factory_testing_ = eeprom_read_byte((uint8_t*)(1)) + 1;
}

/* static */
void PatternGenerator::SaveSettings() {
  eeprom_write_byte(NULL, options_.pack());
  ++factory_testing_;
  if (factory_testing_ >= 5) {
    factory_testing_ = 5;
  }
  eeprom_write_byte((uint8_t*)(1), factory_testing_);
}

/* static */
void PatternGenerator::Evaluate() {
  state_ = 0;
  pulse_duration_counter_ = 0;
  
  Random::Update();
  // Highest bits: clock and random bit.
  state_ |= 0x40;
  state_ |= Random::state() & 0x80;
  
  if (output_clock()) {
    state_ |= OUTPUT_BIT_CLOCK;
  }

  // Refresh only at step changes.
  if (pulse_ != 0) {
    return;
  }
  
  if (options_.output_mode == OUTPUT_MODE_EUCLIDEAN) {
    EvaluateEuclidean();
  } else {
    EvaluateDrums();
  }
}

/* static */
int8_t PatternGenerator::swing_amount() {
  if (options_.swing && output_mode() == OUTPUT_MODE_DRUMS) {
    int8_t value = U8U8MulShift8(settings_.options.drums.randomness, 42 + 1);
    return (!(step_ & 2)) ? value : -value;
  } else {
    return 0;
  }
}

}  // namespace grids