Generated C code inspection in Simulink - Step-by-Step Execution

Concept Flow - Generated C code inspection

Simulink Model

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Code Generation

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Generated C Code

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Code Inspection

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Identify Variables, Functions, Logic

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Trace Execution Step-by-Step

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Understand Behavior and Outputs

Start from a Simulink model, generate C code, then inspect the code step-by-step to understand variables, functions, and logic.

Execution Sample

Simulink

void step() {
  y = a * x + b;
}

A simple generated C function computing output y from inputs a, x, and b.

Execution Table

Step	Variable	Value Before	Operation	Value After	Comment
1	a	2	Read input	2	Input parameter a
2	x	3	Read input	3	Input variable x
3	b	1	Read input	1	Input parameter b
4	y	undefined	Compute y = a * x + b	7	Calculate output y
5	Return	N/A	End of step function	N/A	Output y ready

💡 Step function completes after computing y.

Variable Tracker

Variable	Start	After Step 1	After Step 2	After Step 3	After Step 4	Final
a	2	2	2	2	2	2
x	3	3	3	3	3	3
b	1	1	1	1	1	1
y	undefined	undefined	undefined	undefined	7	7

Key Moments - 2 Insights

Why does variable y have 'undefined' before step 4?

Because y is computed only at step 4, before that it has no assigned value as shown in execution_table row 4.

How do we know the inputs a, x, and b are read correctly?

Execution_table rows 1-3 show inputs a, x, and b are read with their initial values before computation.

Visual Quiz - 3 Questions

Look at the execution_table, what is the value of y after step 4?

A 6

B 7

C undefined

D 1

💡 Hint

Check the 'Value After' column for y at step 4 in execution_table.

At which step are the inputs a, x, and b read?

A Steps 1 to 3

B Step 4

C Step 5

D Before step 1

💡 Hint

Look at execution_table rows 1 to 3 for input reading.

If input b changed to 2, what would be the new value of y after step 4?

A 6

B 7

C 8

D 5

💡 Hint

Use the formula y = a * x + b with a=2, x=3, b=2 from variable_tracker.

Concept Snapshot

Generated C code inspection:
- Start from Simulink model
- Generate C code
- Identify variables and functions
- Trace step-by-step execution
- Understand how inputs produce outputs
- Confirm logic matches model behavior

Full Transcript

This visual execution shows how generated C code from a Simulink model is inspected step-by-step. We start with inputs a=2, x=3, b=1. The code reads these inputs, then computes y = a * x + b, resulting in y=7. Variables a, x, and b remain constant, while y changes from undefined to 7 after computation. Key moments clarify why y is undefined before calculation and confirm input reading steps. The quiz tests understanding of variable values at each step and how changing inputs affects outputs.