From 25c629af16172f72eae9b80378ec70e6bd7e73a5 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Jean-Fran=C3=A7ois=20Nguyen?= <jf@jfng.fr>
Date: Fri, 1 Apr 2022 17:12:05 +0200
Subject: [PATCH] tb: add top-level testbench.

---
 power_fv/__init__.py        |  2 ++
 power_fv/checks/__init__.py |  0
 power_fv/tb.py              | 53 +++++++++++++++++++++++++++++++++++++
 3 files changed, 55 insertions(+)
 create mode 100644 power_fv/checks/__init__.py
 create mode 100644 power_fv/tb.py

diff --git a/power_fv/__init__.py b/power_fv/__init__.py
index b55b1ca..936e341 100644
--- a/power_fv/__init__.py
+++ b/power_fv/__init__.py
@@ -3,8 +3,10 @@ __version__ = metadata.version(__package__)
 
 
 from .dut import *
+from .tb import *
 
 
 __all__ = [
     "Interface",
+    "Testbench",
 ]
diff --git a/power_fv/checks/__init__.py b/power_fv/checks/__init__.py
new file mode 100644
index 0000000..e69de29
diff --git a/power_fv/tb.py b/power_fv/tb.py
new file mode 100644
index 0000000..c38a7be
--- /dev/null
+++ b/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