Convert void data-type (byte array) to uint8_t type
static uint8_t notify_func(const void *data)
{
uint8_t value = ((uint8_t *)data)[7];
return value;
}
Structure data-type as function arguments
static uint8_t notify_func(struct bt_gatt_subscribe_params *params)
{
printk("value_handle : %d", params->value_handle)
}
Declare enums as types
typedef enum {
STRING,
NUMBERS,
COMPLEX,
DATATYPE_COUNT,
INVALID_SENSOR
} sensor_datatype_t;
String initialisation to char pointer
const char *p_mac_addr = "0C:8C:DC:41:E1:EF";
static void print_mac_addr(void)
{
printk("p_mac_addr : %s\n", p_mac_addr)
}
String as function return values
char* get_sensor_mac_addr(void){
return p_mac_addr;
}
Parse unsigned int from byte array pointer
uint32_t get_uint_32(const uint8_t *array, size_t start_index) {
uint32_t value = 0;
value |= array[start_index];
value |= array[start_index + 1] << 8;
value |= array[start_index + 2] << 16;
value |= array[start_index + 3] << 24;
return value;
}
Parse signed int from byte array pointer
int32_t get_int_32(const uint8_t *array, size_t start_index) {
int32_t value = 0;
value |= array[start_index];
value |= array[start_index + 1] << 8;
value |= array[start_index + 2] << 16;
value |= array[start_index + 3] << 24;
return value;
}
Declaring function data-types and callback pattern
// calculation.h
#pragma once
typedef void (*calculation_result_cb_t)(float a, float b, float result);
int init_calculation(calculation_result_cb_t result_callback);
int calculate_sum(float a, float b);
// calculation.c
#include "stdio.h"
#include "calculation.h"
static calculation_result_cb_t calc_result_cb = NULL;
int init_calculation(calculation_result_cb_t result_callback) {
calc_result_cb = result_callback;
return 0;
}
int calculate_sum(float a, float b) {
if (calc_result_cb != NULL) {
calc_result_cb(a, b, a + b);
}
return 0;
}
// main.c
#include <stdio.h>
#include "calculations/calculation.h"
static void result_cb(float a, float b, float result) {
printf("%.2f + %.2f = %.2f\n", a, b, result);
}
int main() {
printf("Callback functions!\n");
init_calculation(result_cb);
if (calculate_sum(10, 20)) {
printf("error\n");
}
return 0;
}
