Where is nus_data_handler declared?

Question

I am editing the ble_app_uart example. Where is the nus_data_handler variable declared? I see the function void nus_data_handler(ble_nus_t * p....).

Stian Røed Hafskjold · Accepted Answer

The function itself is declared and defined in main.c , but the function is used as a pointer, and the function pointer type is declared in ble_nus.h 
 typedef void (*ble_nus_data_handler_t) (ble_nus_t * p_nus, uint8_t * p_data, uint16_t length);
 
 In ble_nus.h you have the following struct, and the data_handler variable is of the above function pointer type. So, in ble_nus_init() you actually assign this variable to point to the nus_data_handler() function in main.c . 
 struct ble_nus_s
{
 uint8_t uuid_type; /**< UUID type for Nordic UART Service Base UUID. */
 uint16_t service_handle; /**< Handle of Nordic UART Service (as provided by the S110 SoftDevice). */
 ble_gatts_char_handles_t tx_handles; /**< Handles related to the TX characteristic (as provided by the S110 SoftDevice). */
 ble_gatts_char_handles_t rx_handles; /**< Handles related to the RX characteristic (as provided by the S110 SoftDevice). */
 uint16_t conn_handle; /**< Handle of the current connection (as provided by the S110 SoftDevice). BLE_CONN_HANDLE_INVALID if not in a connection. */
 bool is_notification_enabled; /**< Variable to indicate if the peer has enabled notification of the RX characteristic.*/
 ble_nus_data_handler_t data_handler; /**< Event handler to be called for handling received data. */
};

Where is nus_data_handler declared?

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