Verification of the MAC unit is performed using cocotb (Coroutine Cosimulation Testbench), a Python-based verification framework that allows for rapid development of complex test scenarios.

The verification strategy focuses on comparing the RTL implementation against a Golden Model written in Python (using standard floating-point arithmetic).

1. Reset Test:

   • Verifies that the core correctly initializes all registers to zero upon assertion of rst_n.
   • Checks that output buffers are cleared.

2. Corner Case Testing:

   • Zero inputs: $0 \times N = 0$.
   • Identity: $1 \times N = N$.
   • Sign flipping: Checking correct sign handling in multiplication.

3. Randomized Regression (1,000 Vectors):

   • Generates random floating-point numbers in the range $[-2.0, 2.0]$.
   • Converts them to BF16 format (software emulation).
   • Drives the RTL simulation via the pseudo-SPI streaming interface.
   • Simulates the expected result in Python using truncation to match BF16 precision behavior.
   • Compares the RTL output against the Python model with a relaxed tolerance (due to BF16 precision loss).

Tests are executed via make in the test/ directory.

# Run all tests
cd test
make

test_mac.test_reset                 PASS
test_mac.test_bf16_mac_simple       PASS
test_mac.test_random_1000_bf16      PASS

The current suite targets 100% Functional Coverage of the pipeline control logic and meaningful arithmetic coverage for standard ML workload ranges.