text: /* Copyright 2020 sekigon-gonnoc
   *
   * 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 2 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/>.
   */
  
  #include "ec_switch_matrix.h"
  
  #include "quantum.h"
  #include "analog.h"
  #include "print.h"
  
  // pin connections
  const uint8_t row_pins[]     = MATRIX_ROW_PINS;
  const uint8_t col_channels[] = MATRIX_COL_CHANNELS;
  const uint8_t mux_sel_pins[] = MUX_SEL_PINS;
  
  _Static_assert(sizeof(mux_sel_pins) == 3, "invalid MUX_SEL_PINS");
  
  static ecsm_config_t config;
  static uint16_t      ecsm_sw_value[MATRIX_ROWS][MATRIX_COLS];
  
  static inline void discharge_capacitor(void) { setPinOutput(DISCHARGE_PIN); }
  static inline void charge_capacitor(uint8_t row) {
      setPinInput(DISCHARGE_PIN);
      writePinHigh(row_pins[row]);
  }
  
  static inline void clear_all_row_pins(void) {
      for (int row = 0; row < sizeof(row_pins); row++) {
          writePinLow(row_pins[row]);
      }
  }
  
  static inline void init_mux_sel(void) {
      for (int idx = 0; idx < sizeof(mux_sel_pins); idx++) {
          setPinOutput(mux_sel_pins[idx]);
      }
  }
  
  static inline void select_mux(uint8_t col) {
      uint8_t ch = col_channels[col];
      writePin(mux_sel_pins[0], ch & 1);
      writePin(mux_sel_pins[1], ch & 2);
      writePin(mux_sel_pins[2], ch & 4);
  }
  
  static inline void init_row(void) {
      for (int idx = 0; idx < sizeof(row_pins); idx++) {
          setPinOutput(row_pins[idx]);
          writePinLow(row_pins[idx]);
      }
  }
  
  // Initialize pins
  int ecsm_init(ecsm_config_t const* const ecsm_config) {
      // save config
      config = *ecsm_config;
  
      // initialize discharge pin as discharge mode
      writePinLow(DISCHARGE_PIN);
      setPinOutput(DISCHARGE_PIN);
  
      // set analog reference
      analogReference(ADC_REF_POWER);
  
      // initialize drive lines
      init_row();
  
      // initialize multiplexer select pin
      init_mux_sel();
  
      // set discharge pin to charge mode
      setPinInput(DISCHARGE_PIN);
  
      return 0;
  }
  
  // Read key value of key (row, col)
  uint16_t ecsm_readkey_raw(uint8_t row, uint8_t col) {
      uint16_t sw_value = 0;
  
      discharge_capacitor();
  
      select_mux(col);
  
      clear_all_row_pins();
  
      cli();
  
      charge_capacitor(row);
  
      sw_value = analogReadPin(ANALOG_PORT);
  
      sei();
  
      return sw_value;
  }
  
  // Update press/release state of key at (row, col)
  bool ecsm_update_key(matrix_row_t* current_row, uint8_t col, uint16_t sw_value) {
      bool current_state = (*current_row >> col) & 1;
  
      // press to release
      if (current_state && sw_value < config.low_threshold) {
          *current_row &= ~(1 << col);
          return true;
      }
  
      // release to press
      if ((!current_state) && sw_value > config.high_threshold) {
          *current_row |= (1 << col);
          return true;
      }
  
      return false;
  }
  
  // Scan key values and update matrix state
  bool ecsm_matrix_scan(matrix_row_t current_matrix[]) {
      bool updated = false;
  
      for (int col = 0; col < sizeof(col_channels); col++) {
          for (int row = 0; row < sizeof(row_pins); row++) {
              ecsm_sw_value[row][col] = ecsm_readkey_raw(row, col);
              updated |= ecsm_update_key(&current_matrix[row], col, ecsm_sw_value[row][col]);
          }
      }
  
      return updated;
  }
  
  // Print key values
  void ecsm_print_matrix(void) {
      for (int row = 0; row < sizeof(row_pins); row++) {
          for (int col = 0; col < sizeof(col_channels); col++) {
              xprintf("%4d", ecsm_sw_value[row][col]);
          }
          xprintf("\n");
      }
  }
  