DescriptionQ466
Q466DVASIC interview problem
Do not repeat the previous five values
TechniquesSystemVerilogStateful randomizationpost_randomize
DifficultyMedium
TopicConstraints
LanguageSystemVerilog
Requirements4 checkpoints
01
Problem
Randomize a four-bit value that differs from each of its five most recent successful values, then maintain that bounded history correctly.
Starting declarationSystemVerilog
rand bit [3:0] value;
bit [3:0] history[$];Example input and output
Use this case to check your interpretationInput
history = {1, 2, 3, 4, 5}; randomize produces 9Output
value = 9; new history = {9, 1, 2, 3, 4}Explanation
Values 1 through 5 are excluded during the solve, then post_randomize inserts 9 and removes the oldest entry.
02
Requirements (4)
- Exclude every value currently stored in the history queue.
- Update history only after a successful solve.
- Keep at most five prior values, newest first.
- Check randomize() failure explicitly at the call site.