Functional Coverage - Part2

You define:

During simulation, pkt_type only takes values 0, 2, and 4.
What is the coverage percentage?

• 100% — all bins got hit at least once.

• 66.66% — one bin (data) is incomplete.

• 33.33% — only one bin hit counts.

• Depends on how generous your simulator is feeling.

This means:

• All (a=3, b=anything) combinations are ignored.

• Only (a=3, b=7) is ignored.

• All (b=7, a=anything) combinations are ignored.

• The cross is skipped entirely.

option.at_least = 3;

for a bin. The bin is hit twice in simulation.
Coverage result:

• 100% — it was hit at least once.

• 66% — partial credit given.

• 0% — didn’t meet the minimum hits required.

• Depends on per_instance.

Answer explanation

💡 The bin is considered uncovered until it reaches the at_least threshold.

The signal addr is 16 bits wide. What happens?

• Simulator automatically truncates to 8 bits.

• Tool creates bins for values 0–255 and ignores higher ones.

• Compilation error due to mismatch.

• Bins cover 0–255, but values >255 go into the default bin.

Answer explanation

💡 Values outside the specified range are ignored unless a default bin is defined.

You run a test where cg_inst1 hits all bins, cg_inst2 hits none.
If per_instance = 0, coverage is:

• 50%

• 100%

• 0%

• Undefined

Answer explanation

💡 Coverage is merged across instances, so one fully-covered instance makes total coverage look perfect.

How many cross bins will be created?

• 2

• 3

• 4

• 8

Answer explanation

2 bins for i × 2 bins for j = 4 cross bins.

What is the coverage if the Hit seen : 10 , 12 ?

• 33%

• 66%
  

• 100%

• 90%

Answer explanation

Three bins {10}, {11}, {12}. Only 10 and 12 are hit → 2/3 bins covered = 66%.

How many bins will the cross have?

• 1

• 2

• 4

• 1 + auto bins ✅

Answer explanation

One named bin (low_a_lo_b) plus the simulator may auto-generate the others unless iff or illegal_bins are used to remove them.