MISRA-C:2012 Rules & Directives

/* MISRA C:2012 key rule examples for embedded automotive C */

/* Rule 10.1: Operands shall not be of inappropriate essential type */
void rule_10_1(void) {
    int8_t x = 5;
    int8_t y = 10;
    /* Violation: shift of signed integer (undefined behaviour if x<0) */
    /* int8_t z = x << y; */
    /* Fix: use unsigned type for bit operations */
    uint8_t xu = (uint8_t)x;
    uint8_t z = xu << 1u;  /* compliant */
}

/* Rule 10.4: Both operands of arithmetic/bitwise operator shall */
/* have same essential type category                              */
void rule_10_4(void) {
    uint8_t  a = 10u;
    uint16_t b = 100u;
    /* Violation: different essential types in addition */
    /* uint16_t c = a + b; */
    /* Fix: explicit cast to match types */
    uint16_t c = (uint16_t)a + b;  /* compliant */
}

/* Rule 14.4: Condition of if/while/for shall be essentially boolean */
void rule_14_4(uint8_t error_code) {
    /* Violation: integer used as boolean condition */
    /* if (error_code) { ... } */
    /* Fix: explicit boolean comparison */
    if (error_code != 0u) {
        /* handle error */
    }
}

/* Rule 17.7: Return value of non-void function shall be used */
void rule_17_7(void) {
    /* Violation: return value of Adc_ReadGroup ignored */
    /* Adc_ReadGroup(ADC_GROUP_1, buffer); */
    /* Fix: check return value */
    Std_ReturnType ret = Adc_ReadGroup(ADC_GROUP_1, buffer);
    if (ret != E_OK) { fault_handler(); }
}