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Course contents

  • How to Use This Puzzle Bank
  • SystemVerilog Language Puzzles25
    • Datatype and Bit Puzzles
      • X-Bit Comparisons and Mixed Arithmetic
      • Signed vs Unsigned Comparison Trap
      • Type Cast Controls Sign Extension
      • Signed Part-Select Is Still Unsigned
      • X Collapse into 2-State `int`
      • Case Equality vs Wildcard Equality
    • Fork Join Puzzles
    • Queue and Array Puzzles
    • String and Casting Puzzles
    • SystemVerilog Language Puzzles: Tricky Q&A
  • Difficulty Guide
  • Full Topic Map
  • Interview-Day Tips
  • OOP & Testbench Puzzles25
  • Concurrency & Timing Puzzles25
  • Randomization & Constraint Puzzles25
  • SVA Assertion Puzzles25
  • Functional Coverage Puzzles25
  • Logic & Aptitude Puzzles25
  • Scenario & Debug Puzzles25
  • Interview Prep: Puzzle Rounds5
  • DV Puzzle Cheatsheet
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‹SystemVerilog Language Puzzles
  1. Topics
  2. DV Interview Puzzles
  3. SystemVerilog Language Puzzles
  4. Datatype and Bit Puzzles

VLSI DV Interview Puzzles · All levels

Datatype and Bit Puzzles

These puzzles target the places where SystemVerilog silently changes interpretation based on type: 4-state vs 2-state storage, signedness propagation, and operator-specific rules. Strong candidates can predict exact outputs by tracking width, sign, and unknown-bit semantics at every step.

  • 6topics
  • 6lessons

Topics in this section

  1. 1X-Bit Comparisons and Mixed Arithmetic1 lesson
  2. 2Signed vs Unsigned Comparison Trap1 lesson
  3. 3Type Cast Controls Sign Extension1 lesson
  4. 4Signed Part-Select Is Still Unsigned1 lesson
  5. 5X Collapse into 2-State `int`1 lesson
  6. 6Case Equality vs Wildcard Equality1 lesson
On this page

    About this puzzle set

    These puzzles target the places where SystemVerilog silently changes interpretation based on type: 4-state vs 2-state storage, signedness propagation, and operator-specific rules. Strong candidates can predict exact outputs by tracking width, sign, and unknown-bit semantics at every step.

    Puzzles in this topic

    Diagram
    1. X-Bit Comparisons and Mixed Arithmetic  [Easy]
    2. Signed vs Unsigned Comparison Trap  [Medium]
    3. Type Cast Controls Sign Extension  [Medium]
    4. Signed Part-Select Is Still Unsigned  [Hard]
    5. X Collapse into 2-State `int`  [Medium]
    6. Case Equality vs Wildcard Equality  [Easy]

    Work each puzzle before reading the solution: predict the exact output or answer, name the rule that governs it, then check yourself.

    SV scheduling regions at puzzle scale

    Diagram
    SYSTEMVERILOG EVENT REGIONS (SIMPLIFIED ORDER)
    
    time slot T
       |
       +--> ACTIVE   : blocking statements, RHS sampling
       +--> INACTIVE : #0 queued work
       +--> NBA      : non-blocking LHS updates commit
       +--> OBSERVED : assertions sample stable design values
       +--> REACTIVE : testbench/program reaction code
    
    If behavior looks impossible, ask: "Which region saw which value?"

    Related topics

    • SystemVerilog Language Puzzles section

    • VLSI DV Interview Puzzles hub

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    See also

    • Fork Join Puzzles
    • Queue and Array Puzzles
    • String and Casting Puzzles