text: /**
   * Copyright (c) 2012 - 2020, Nordic Semiconductor ASA
   *
   * All rights reserved.
   *
   * Redistribution and use in source and binary forms, with or without modification,
   * are permitted provided that the following conditions are met:
   *
   * 1. Redistributions of source code must retain the above copyright notice, this
   *    list of conditions and the following disclaimer.
   *
   * 2. Redistributions in binary form, except as embedded into a Nordic
   *    Semiconductor ASA integrated circuit in a product or a software update for
   *    such product, must reproduce the above copyright notice, this list of
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   *    materials provided with the distribution.
   *
   * 3. Neither the name of Nordic Semiconductor ASA nor the names of its
   *    contributors may be used to endorse or promote products derived from this
   *    software without specific prior written permission.
   *
   * 4. This software, with or without modification, must only be used with a
   *    Nordic Semiconductor ASA integrated circuit.
   *
   * 5. Any software provided in binary form under this license must not be reverse
   *    engineered, decompiled, modified and/or disassembled.
   *
   * THIS SOFTWARE IS PROVIDED BY NORDIC SEMICONDUCTOR ASA "AS IS" AND ANY EXPRESS
   * OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
   * OF MERCHANTABILITY, NONINFRINGEMENT, AND FITNESS FOR A PARTICULAR PURPOSE ARE
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   * GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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   *
   */
  /**
   * @file
   * @brief Implementation of mouse_sensor_emulate.h.
   */
  
  #include "mouse_sensor_emulator.h"
  
  #define MOUSE_SENSOR_TIMER              NRF_TIMER1                ///< Timer 1 is used to emulate the mouse.
  #define MOUSE_SENSOR_TIMER_PERPOWER_Msk POWER_PERPOWER_TIMER1_Msk ///< Power mask for Timer 1 peripheral.
  #define MOUSE_SENSOR_TIMER_IRQn         TIMER1_IRQn               ///< Mouse interrupt set to Timer 1's interrupt.
  #define MOUSE_SENSOR_TIMER_IRQ_HANDLER  TIMER1_IRQHandler         ///< Mouse interrupt handler set to Timer 1's interrupt handler.
  
  /**
   * @struct mouse_sensor_status_t
   * @brief Data structure holding internal mouse sensor variables.
   */
  typedef struct
  {
      int32_t acc_x;        ///< Accumulator holding accumulated mouse samples.
      int32_t acc_y;        ///< Accumulator holding accumulated mouse samples.
      bool    enabled;      ///< Mouse sensor enabled / disabled flag.
      bool    sample_ready; ///< Mouse sensor sample ready flag.
  } mouse_sensor_status_t;
  
  static mouse_sensor_status_t mouse_sensor_status; ///< Internal mouse sensor variables.
  
  bool mouse_sensor_init(mouse_sensor_sample_period_t sample_period)
  {
      mouse_sensor_status.acc_x        = 0;
      mouse_sensor_status.acc_y        = 0;
      mouse_sensor_status.sample_ready = false;
      mouse_sensor_status.enabled      = false;
  
      MOUSE_SENSOR_TIMER->TASKS_STOP  = 1;
      MOUSE_SENSOR_TIMER->TASKS_CLEAR = 1;
      MOUSE_SENSOR_TIMER->INTENCLR    = 0xffffffff;
      MOUSE_SENSOR_TIMER->INTENSET    = TIMER_INTENSET_COMPARE0_Msk;
  
      MOUSE_SENSOR_TIMER->SHORTS    = (1 << TIMER_SHORTS_COMPARE0_CLEAR_Pos);
      MOUSE_SENSOR_TIMER->PRESCALER = 4; // Ensures 1 us resolution @ 16MHz
  
      switch (sample_period)
      {
          case MOUSE_SENSOR_SAMPLE_PERIOD_4_MS:
              MOUSE_SENSOR_TIMER->CC[0] = 4000;
              break;
  
          case MOUSE_SENSOR_SAMPLE_PERIOD_8_MS:
          default:
              MOUSE_SENSOR_TIMER->CC[0] = 8000;
              break;
      }
  
      NVIC_ClearPendingIRQ(MOUSE_SENSOR_TIMER_IRQn);
      NVIC_EnableIRQ(MOUSE_SENSOR_TIMER_IRQn);
      return true;
  }
  
  
  void mouse_sensor_enable(void)
  {
      MOUSE_SENSOR_TIMER->TASKS_CLEAR = 1;
      MOUSE_SENSOR_TIMER->TASKS_START = 1;
  }
  
  
  void mouse_sensor_disable(void)
  {
      MOUSE_SENSOR_TIMER->TASKS_STOP = 1;
  }
  
  
  bool mouse_sensor_data_is_ready(void)
  {
      return mouse_sensor_status.sample_ready;
  }
  
  
  bool mouse_sensor_read(uint8_t * out_mouse_packet)
  {
      if (mouse_sensor_status.sample_ready)
      {
          out_mouse_packet[NRFR_REPORT_ID]               = NRFR_MOUSE_MOV_REPORT_ID;
          out_mouse_packet[NRFR_MOUSE_MOV_XLSBYTE]       = mouse_sensor_status.acc_y;
          out_mouse_packet[NRFR_MOUSE_MOV_YLSNIB_XMSNIB] = ((mouse_sensor_status.acc_x << 4) & 0xf0) |
                                                           ((mouse_sensor_status.acc_y >> 8) & 0x0f);
          out_mouse_packet[NRFR_MOUSE_MOV_YMSBYTE] = mouse_sensor_status.acc_x >> 4;
          mouse_sensor_status.acc_x                = 0;
          mouse_sensor_status.acc_y                = 0;
          mouse_sensor_status.sample_ready         = false;
          return true;
      }
      else
      {
          return false;
      }
  }
  
  
  /**
   * @brief Mouse sensor timer interrupt.
   *
   * Mouse sensor accumulator is updated and the callback
   * mouse_sensor_new_sample_generated_cb() is made to the application.
   */
  void MOUSE_SENSOR_TIMER_IRQ_HANDLER(void)
  {
      static uint8_t sample_cnt = 0;
      int32_t        new_value  = 0;
  
      if (sample_cnt < 20)
      {
          sample_cnt++;
      }
      else
      {
          sample_cnt = 0;
      }
  
      if (sample_cnt < 10)
      {
          new_value = 2;
      }
      else
      {
          new_value = -2;
      }
  
      mouse_sensor_status.acc_x       += new_value;
      mouse_sensor_status.acc_y       += new_value;
      mouse_sensor_status.sample_ready = true;
  
      MOUSE_SENSOR_TIMER->EVENTS_COMPARE[0] = 0;
  
      mouse_sensor_new_sample_generated_cb();
  }
  
  
  