tb: add top-level testbench.

power_fv/__init__.py

@@ -3,8 +3,10 @@ __version__ = metadata.version(__package__)
 
 
 from .dut import *
+from .tb import *
 
 
 __all__ = [
     "Interface",
+    "Testbench",
 ]

power_fv/tb.py

@@ -0,0 +1,53 @@
+from amaranth import *
+from amaranth.asserts import *
+
+
+__all__ = ["Testbench"]
+
+
+class Testbench(Elaboratable):
+    def __init__(self, check, dut, *, t_post, t_pre=None, t_start=0):
+        if not isinstance(t_post, int) or t_post < 0:
+            raise ValueError("t_post must be a non-negative integer, not {!r}"
+                             .format(t_post))
+        if t_pre is None:
+            t_pre = t_post
+        if not isinstance(t_pre, int) or t_pre < 0:
+            raise ValueError("t_pre must be a non-negative integer, not {!r}"
+                             .format(t_pre))
+        if t_pre > t_post:
+            raise ValueError("t_pre ({}) must be lesser than or equal to t_post ({})"
+                             .format(t_pre, t_post))
+        if not isinstance(t_start, int) or t_start < 0:
+            raise ValueError("t_start must be a non-negative integer, not {!r}"
+                             .format(t_start))
+        if t_start > t_pre:
+            raise ValueError("t_start ({}) must be lesser than or equal to t_pre ({})"
+                             .format(t_start, t_pre))
+
+        self.t_post  = t_post
+        self.t_pre   = t_pre
+        self.t_start = t_start
+
+        self.check = check
+        self.dut   = dut
+
+    def elaborate(self, platform):
+        m = Module()
+
+        timer = Signal(range(self.t_post + 1))
+        with m.If(timer != self.t_post):
+            m.d.sync += timer.eq(timer + 1)
+
+        m.submodules.check = ResetInserter(timer < self.t_start)(self.check)
+        m.submodules.dut   = self.dut
+
+        m.d.comb += [
+            self.check.dut .eq(self.dut.pfv),
+            self.check.pre .eq(timer == self.t_pre),
+            self.check.post.eq(timer == self.t_post),
+        ]
+
+        m.d.comb += Assume(ResetSignal() == Initial())
+
+        return m