Generated C code inspection in Simulink - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to declare a variable for storing the output signal.

Simulink

double [1];

Drag options to blanks, or click blank then click option'

Aint

Boutput_signal

Csignal_output

Dfloat

Attempts:

3 left

💡 Hint

Common Mistakes

Using a data type instead of a variable name.

Choosing a variable name that does not match the output.

The variable output_signal is declared as a double to store the output value.

2fill in blank

medium

Complete the code to assign the input value to the variable.

Simulink

[1] = input_signal;

Drag options to blanks, or click blank then click option'

Asignal_input

Binput_signal

Coutput_signal

Dresult

Attempts:

3 left

💡 Hint

Common Mistakes

Assigning the variable to itself.

Using the input variable on the left side.

The variable output_signal receives the value from input_signal.

3fill in blank

hard

Fix the error in the function call to update the output.

Simulink

updateOutput([1]);

Drag options to blanks, or click blank then click option'

Aoutput_signal

Bsignal

Cresult

Dinput_signal

Attempts:

3 left

💡 Hint

Common Mistakes

Passing the input variable instead of the output.

Using an undefined variable.

The function updateOutput should be called with the output variable output_signal.

4fill in blank

hard

Fill both blanks to create a for loop that iterates over 10 elements and sums them.

Simulink

double sum = 0;
for (int [1] = 0; [2] < 10; [1]++) {
    sum += data[[1]];
}

Drag options to blanks, or click blank then click option'

Ai

Bj

Ck

Dindex

Attempts:

3 left

💡 Hint

Common Mistakes

Using different variable names in the loop header.

Using a variable name not declared in the loop.

The loop variable i is used consistently to iterate from 0 to 9.

5fill in blank

hard

Fill all three blanks to create a dictionary-like structure in C using structs and initialize it.

Simulink

typedef struct {
    char* [1];
    int [2];
} [3];

[3] data[] = { {"speed", 100}, {"power", 200} };

Drag options to blanks, or click blank then click option'

Aname

Bvalue

CParameter

DDataPoint

Attempts:

3 left

💡 Hint

Common Mistakes

Mixing up field names.

Using inconsistent struct names.

The struct Parameter has fields name and value to hold key-value pairs.

Practice

1. What is the main purpose of inspecting generated C code from a Simulink model?

easy

A. To run the Simulink model faster in simulation

B. To create new Simulink blocks automatically

C. To verify the correctness and understand the behavior of the generated code

D. To convert C code back into Simulink diagrams

Solution

1. Step 1: Understand the role of generated code inspection

   Generated C code inspection is used to check if the code matches the Simulink model's logic and to understand how the model is translated into code.

2. Step 2: Eliminate unrelated options

   Creating new blocks, speeding simulation, or converting code back to diagrams are not purposes of code inspection.

3. Final Answer:

   To verify the correctness and understand the behavior of the generated code -> Option C

4. Quick Check:

   Code inspection = verify and understand code [OK]

Hint: Code inspection checks correctness and logic match [OK]

Common Mistakes:

• Thinking code inspection creates new blocks
• Confusing code inspection with simulation speedup
• Assuming code inspection converts code back to diagrams

2. Which Simulink tool is primarily used to generate C code from a model?

easy

A. Simulink Profiler

B. Simulink Data Inspector

C. Simulink Real-Time

D. Simulink Coder

Solution

1. Step 1: Identify the tool for code generation

   Simulink Coder is the tool designed to generate C and C++ code from Simulink models.

2. Step 2: Confirm other tools' purposes

   Profiler measures performance, Data Inspector visualizes signals, Real-Time runs models on hardware, none generate code.

3. Final Answer:

   Simulink Coder -> Option D

4. Quick Check:

   Code generation tool = Simulink Coder [OK]

Hint: Simulink Coder generates C code from models [OK]

Common Mistakes:

• Confusing Profiler with code generator
• Mixing Data Inspector with code generation
• Assuming Real-Time generates code

3. Given the following snippet from generated C code, what does the variable rtU.inputSignal represent?

/* Model step function */
void model_step(void) {
  real_T output = rtU.inputSignal * 2.0;
  rtY.outputSignal = output;
}

medium

A. An output signal from the model

B. An input signal to the model

C. A local temporary variable

D. A constant value defined in the code

Solution

1. Step 1: Analyze variable naming conventions

   In generated code, rtU prefix usually denotes inputs to the model, so rtU.inputSignal is an input.

2. Step 2: Check usage in code

   The code multiplies rtU.inputSignal by 2 and assigns to output, confirming it is an input value.

3. Final Answer:

   An input signal to the model -> Option B

4. Quick Check:

   rtU = inputs, rtY = outputs [OK]

Hint: rtU prefix means input signals in generated code [OK]

Common Mistakes:

• Thinking rtU is output or local variable
• Assuming inputSignal is a constant
• Confusing variable scope

4. You find this line in generated C code:

int32_T counter = 0
counter += 1;

What is the error here?

medium

A. Missing semicolon after the first statement

B. Incorrect variable type for counter

C. counter cannot be incremented like this

D. Variable counter should be declared as float

Solution

1. Step 1: Check syntax of variable declaration

   The first line declares counter but misses a semicolon at the end, which is required in C.

2. Step 2: Validate increment statement

   The increment counter += 1; is correct syntax and valid for int32_T type.

3. Final Answer:

   Missing semicolon after the first statement -> Option A

4. Quick Check:

   Every C statement ends with ; [OK]

Hint: Check for missing semicolons in C code lines [OK]

Common Mistakes:

• Ignoring missing semicolon errors
• Thinking increment syntax is wrong
• Confusing variable types unnecessarily

5. You want to optimize generated C code by removing unused signals. Which step should you take in Simulink before generating code?

hard

A. Use the Code Mappings editor to mark unused signals as 'Exclude from code'

B. Enable signal logging for all signals

C. Increase the sample time of all blocks

D. Disable the Simulink Coder entirely

Solution

1. Step 1: Understand code optimization options

   Simulink allows marking signals as unused in the Code Mappings editor to exclude them from generated code.

2. Step 2: Evaluate other options

   Enabling logging increases code size, increasing sample time changes model behavior, disabling coder stops code generation.

3. Final Answer:

   Use the Code Mappings editor to mark unused signals as 'Exclude from code' -> Option A

4. Quick Check:

   Exclude unused signals via Code Mappings [OK]

Hint: Mark unused signals to exclude in Code Mappings editor [OK]

Common Mistakes:

• Enabling logging increases code size
• Changing sample time affects model timing
• Disabling coder stops code generation