C语言中回调函数的含义与使用场景详解(2)

typedef int (*my_calculate_t)(int a, int b);
static int cal_sum(int a, int b)
{
    printf("now is sum\r\n");
    return a + b;
}
static int cal_sub(int a, int b)
{
    printf("now is sub\r\n");
    return a - b;
}
static int cal_mul(int a, int b)
{
    printf("now is mul\r\n");
    return a * b;
}
static my_calculate_t s_cal = cal_sum;
static int test2_cal (int a, int b)
{
    int result = 0;
    if(s_cal) {
        result = s_cal(a ,b);
        printf("result=%d\r\n", result);
    }
    return result;
}
void app_main(void)
{
    printf("init done\r\n");
    int m = 10, n = 1, ret;
    ret = test2_cal(m, n);
}

typedef int (*my_calculate_t)(int a, int b);
static int cal_sum(int a, int b)
{
    printf("now is sum\r\n");
    return a + b;
}
static int cal_sub(int a, int b)
{
    printf("now is sub\r\n");
    return a - b;
}
static int cal_mul(int a, int b)
{
    printf("now is mul\r\n");
    return a * b;
}
static my_calculate_t s_c_array[5] = {cal_sum, cal_sub};
static int test1_cal(int a, int b)
{
    volatile int result = 0;
    volatile size_t i = 0;
    for(i=0; i<(sizeof(s_c_array)/sizeof(my_calculate_t)); i++) {
        if (s_c_array[i] != NULL){
            result = s_c_array[i](a, b);
            printf("i=%d, result=%d\r\n",i, result);
        }
    }
    return result;
}
static void my_cal_calculate_register(my_calculate_t cal)
{
    for(size_t i=0; i<(sizeof(s_c_array)/sizeof(my_calculate_t)); i++) {
        if (s_c_array[i] == NULL){
            s_c_array[i] = cal;
            return;
        }
    }
}
static void my_cal_calculate_unregister(my_calculate_t cal)
{
    for(size_t i=0; i<(sizeof(s_c_array)/sizeof(my_calculate_t)); i++) {
        if (s_c_array[i] == cal){
            s_c_array[i] = NULL;
            return;
        }
    }
}
void app_main(void)
{
    printf("init done\r\n");
    int m = 10, n = 2, ret;
    printf("test 1***************begin\r\n");
    test1_cal(m, n);
    printf("test 1***************end\r\n");
    printf("test 2***************begin\r\n");
    my_cal_calculate_register(cal_mul);
    test1_cal(m, n);
    printf("test 2***************end\r\n");
    printf("test 3***************begin\r\n");
    my_cal_calculate_unregister(cal_mul);
    test1_cal(m, n);
    printf("test 3***************begin\r\n");
}

typedef int (*my_calculate_t)(int a, int b);
typedef int (*add_self_t)(int a);
typedef void (*send_to_printf_t)(int a);
typedef struct my_test_struct_t
{
    my_calculate_t m_calculate;
    add_self_t m_add;
    send_to_printf_t m_printf;
}my_test_struct_t;
static int cal_sub(int a, int b)
{
    printf("now is sum\r\n");
    return a - b;
}
static int cal_add_self(int a)
{
    return a+1;
}
static void cal_send_to_printf(int a)
{
    printf("total is %d\r\n", a);
}
static void cal_send_to_printf2(int a)
{
    printf("now total is %d\r\n", a);
}
my_test_struct_t s_test = {
    .m_calculate = cal_sub,
    .m_add = cal_add_self,
    .m_printf = cal_send_to_printf,
};
static int test1_cal(int a, int b)
{
    int result = 0;
    if(s_test.m_calculate){
        result = s_test.m_calculate(a,b);
        printf("result1 is %d\r\n", result);
    }
    if(s_test.m_add){
        result = s_test.m_add(result);
        printf("result1 is %d\r\n", result);
    }
    if(s_test.m_printf) {
        s_test.m_printf(result);
    }
    return result;
}
void app_main(void)
{
    printf("init done\r\n");
    int m = 10, n = 2;
    printf("test 1***************begin\r\n");
    test1_cal(m, n);
    printf("test 1***************end\r\n");
    printf("test 2***************begin\r\n");
    s_test.m_printf = cal_send_to_printf2;
    test1_cal(m, n);
    printf("test 2***************end\r\n");
}