TLB/test_cam_entry.py

   1 from nmigen.compat.sim import run_simulation
   2
   3 from test_helper import check
   4 from CamEntry import CamEntry
   5
   6 # This function allows for the easy setting of values to the Cam Entry
   7 # unless the key is incorrect
   8 # Arguments:
   9 #   dut: The CamEntry being tested
  10 #   c (command): NA (0), Read (1), Write (2), Reserve (3)
  11 #   k (key): The key to be set
  12 #   d (data): The data to be set
  13 def set_cam_entry(dut, c, k, d):
  14     # Write desired values
  15     yield dut.command.eq(c)
  16     yield dut.key_in.eq(k)
  17     yield dut.data_in.eq(d)
  18     yield
  19     # Reset all lines
  20     yield dut.command.eq(0)
  21     yield dut.key_in.eq(0)
  22     yield dut.data_in.eq(0)
  23     yield
  24
  25 # Checks the key state of the CAM entry
  26 # Arguments:
  27 #   dut: The CamEntry being tested
  28 #   k (Key): The expected key
  29 #   op (Operation): (0 => ==), (1 => !=)
  30 def check_key(dut, k, op):
  31     out_k = yield dut.key
  32     check("Key", out_k, k, op)
  33
  34 # Checks the data state of the CAM entry
  35 # Arguments:
  36 #   dut: The CamEntry being tested
  37 #   d (Data): The expected data
  38 #   op (Operation): (0 => ==), (1 => !=)
  39 def check_data(dut, d, op):
  40     out_d = yield dut.data
  41     check("Data", out_d, d, op)
  42
  43 # Checks the match state of the CAM entry
  44 # Arguments:
  45 #   dut: The CamEntry being tested
  46 #   m (Match): The expected match
  47 #   op (Operation): (0 => ==), (1 => !=)
  48 def check_match(dut, m, op):
  49     out_m = yield dut.match
  50     check("Match", out_m, m, op)
  51
  52 # Checks the state of the CAM entry
  53 # Arguments:
  54 #   dut: The CamEntry being tested
  55 #   k (key): The expected key
  56 #   d (data): The expected data
  57 #   m (match): The expected match
  58 #   k_op (Operation): The operation for the key assertion (0 => ==), (1 => !=)
  59 #   d_op (Operation): The operation for the data assertion (0 => ==), (1 => !=)
  60 #   m_op (Operation): The operation for the match assertion (0 => ==), (1 => !=)
  61 def check_all(dut, k, d, m, k_op, d_op, m_op):
  62     yield from check_key(dut, k, k_op)
  63     yield from check_data(dut, d, d_op)
  64     yield from check_match(dut, m, m_op)
  65
  66 # This testbench goes through the paces of testing the CamEntry module
  67 # It is done by writing and then reading various combinations of key/data pairs
  68 # and reading the results with varying keys to verify the resulting stored
  69 # data is correct.
  70 def testbench(dut):
  71     # Check write
  72     command = 2
  73     key = 1
  74     data = 1
  75     match = 0
  76     yield from set_cam_entry(dut, command, key, data)
  77     yield from check_all(dut, key, data, match, 0, 0, 0)
  78
  79     # Check read miss
  80     command = 1
  81     key = 2
  82     data = 1
  83     match = 0
  84     yield from set_cam_entry(dut, command, key, data)
  85     yield from check_all(dut, key, data, match, 1, 0, 0)
  86
  87     # Check read hit
  88     command = 1
  89     key = 1
  90     data = 1
  91     match = 1
  92     yield from set_cam_entry(dut, command, key, data)
  93     yield from check_all(dut, key, data, match, 0, 0, 0)
  94
  95     # Check overwrite
  96     command = 2
  97     key = 2
  98     data = 5
  99     match = 0
 100     yield from set_cam_entry(dut, command, key, data)
 101     yield
 102     yield from check_all(dut, key, data, match, 0, 0, 0)
 103
 104     # Check read hit
 105     command = 1
 106     key = 2
 107     data = 5
 108     match = 1
 109     yield from set_cam_entry(dut, command, key, data)
 110     yield from check_all(dut, key, data, match, 0, 0, 0)
 111
 112     # Extra clock cycle for waveform
 113     yield
 114
 115 if __name__ == "__main__":
 116     dut = CamEntry(4, 4)
 117     run_simulation(dut, testbench(dut), vcd_name="Waveforms/cam_entry_test.vcd")
 118     print("CamEntry Unit Test Success")