text: /**
   * Copyright (c) 2009 - 2020, Nordic Semiconductor ASA
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   * All rights reserved.
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   * Redistribution and use in source and binary forms, with or without modification,
   * are permitted provided that the following conditions are met:
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   *
   * 2. Redistributions in binary form, except as embedded into a Nordic
   *    Semiconductor ASA integrated circuit in a product or a software update for
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   *
   * 3. Neither the name of Nordic Semiconductor ASA nor the names of its
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   *
   * 4. This software, with or without modification, must only be used with a
   *    Nordic Semiconductor ASA integrated circuit.
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  #ifndef CHERRY8x16_H
  #define CHERRY8x16_H
  
  /*lint ++flb "Enter library region" */
  
  #include <stdbool.h>
  #include <stdint.h>
  
  #ifdef __cplusplus
  extern "C" {
  #endif
  
  /** @file
  * @brief Cherry 8x16 keyboard matrix driver
  *
  *
  * @defgroup nrf_drivers_cherry8x16 Cherry 8x16 keyboard matrix driver
  * @{
  * @ingroup ext_drivers
  * @brief Cherry 8x16 keyboard matrix driver.
  */
  
  #define CHERRY8x16_MAX_NUM_OF_PRESSED_KEYS 6 //!< Maximum number of pressed keys kept in buffers
  #define CHERRY8x16_DEFAULT_KEY_LOOKUP_MATRIX (const uint8_t*)0 //!< If passed to @ref cherry8x16_init, default lookup matrix will be used
  
  #define KEY_PACKET_MODIFIER_KEY_INDEX (0) //!< Index in the key packet where modifier keys such as ALT and Control are stored
  #define KEY_PACKET_RESERVED_INDEX (1) //!< Index in the key packet where OEMs can store information
  #define KEY_PACKET_KEY_INDEX (2) //!< Start index in the key packet where pressed keys are stored
  #define KEY_PACKET_MAX_KEYS (6) //!< Maximum number of keys that can be stored into the key packet
  #define KEY_PACKET_SIZE (KEY_PACKET_KEY_INDEX + KEY_PACKET_MAX_KEYS) //!< Total size of the key packet in bytes
  #define KEY_PACKET_NO_KEY (0) //!< Value to be stored to key index to indicate no key is pressed
  
  
  /**
   * Describes return values for:
   * @ref cherry8x16_init
   */
  typedef enum
  {
    CHERRY8x16_OK, /*!< Operation was succesful. */
    CHERRY8x16_NOT_DETECTED, /*!< Product/Revision ID was not what was expected */
    CHERRY8x16_INVALID_PARAMETER /*!< Given parameters were not valid */
  } cherry8x16_status_t;
  
  /**
   * @brief Function for initializing the driver.
   *
   * @note Before calling this function, setup row_port as IO inputs with pulldowns enabled and column_port as IO outputs.
   *
   * @param row_port Pointer to GPIO port address that is used as key matrix row input.
   * @param column_port Pointer to GPIO port address that is used as key matrix column output.
   * @param key_lookup_matrix If NULL, use a default key lookup matrix. Otherwise pointer to a 128 (8x16) element array containing HID keycodes.
   * @return
   * @retval CHERRY8X16_OK Peripheral was initialized succesfully.
   * @retval CHERRY8X16_NOT_DETECTED Could not detect the peripheral.
   */
  cherry8x16_status_t cherry8x16_init(const uint8_t volatile * row_port, uint16_t * column_port, const uint8_t * key_lookup_matrix);
  
  /**
   * @brief Function for creating a new key packet if new data is available and key ghosting is not detected.
   *
   * @param p_key_packet Array that will hold the created key packet. Previously created packet will be discarded.
   * @param p_key_packet_size Key packet size in bytes.
   * @return
   * @retval true If new packet was created.
   * @retval false  If packet was not created.
   */
  bool cherry8x16_new_packet(const uint8_t ** p_key_packet, uint8_t *p_key_packet_size);
  
  /**
   *@}
   **/
  
  /*lint --flb "Leave library region" */
  
  #ifdef __cplusplus
  }
  #endif
  
  #endif
  