---
record-id: MISRA-REC-001
project: demo-epb
date: 2026-05-11
status: Approved
---

# MISRA Deviation Record MISRA-REC-001

| Field             | Value                                       |
|-------------------|---------------------------------------------|
| Record ID         | MISRA-REC-001                              |
| Date              | 2026-05-11                                  |
| File              | `src/apply_controller.c`                    |
| Function          | `apply_ctrl_step_50ms`                      |
| Line              | 64                                          |
| Standard          | MISRA C:2012                                |
| Rule              | Rule 15.5 (Advisory) — "A function should have a single point of exit" |
| ASIL              | D                                           |
| Status            | Approved                                    |

---

## 1. Code excerpt

```c
void apply_ctrl_step_50ms(const ApplyInputs* in)
{
    if (in == NULL) {
        s_ctx.last_error = EPB_EINVAL;
        return;            /* <-- early exit */
    }
    ...
}
```

## 2. Rationale

The NULL pointer check as an early exit significantly improves readability versus a nested variant with a single `return` at the end. MISRA Rule 15.5 is **Advisory**, not **Required**.

The early exit has clearly defined semantics (input validation) and does not impair verifiability; on the contrary, the separate path is unambiguously covered in the unit test `test_null_input`.

## 3. Alternative considered

Single-exit variant:

```c
void apply_ctrl_step_50ms(const ApplyInputs* in)
{
    if (in == NULL) {
        s_ctx.last_error = EPB_EINVAL;
    } else {
        /* entire step logic nested in else branch */
        ...
    }
}
```

Rejected because the additional nesting makes the state machine harder to read without gaining functional equivalence relative to the early-exit variant.

## 4. Safety impact

None. The early exit is deterministic and covered by the unit test.

## 5. Approval

| Role            | Name             | Date        | Signature |
|-----------------|------------------|-------------|-----------|
| Technical Lead  | Stefan Lohmaier  | 2026-05-11  | (demo)    |
| Safety Manager  | (in real project)| 2026-05-11  | (demo)    |

## 6. Scope

This deviation applies only to this specific code site. Other early-exit sites require separate records.