Tests/cocotb (#19)

* wip

* reorg

* update sv int

* apb4 working

* apb3 working

* version bump + ignore runner warning

* remove redundant check

* adding log on failure

* cleaning up verilator version issue

* devcontainer

* Fix missing libpython in GitHub Actions CI environment (#21)

* Initial plan

* Install libpython in GitHub Actions for cocotb tests

Co-authored-by: arnavsacheti <36746504+arnavsacheti@users.noreply.github.com>

---------

Co-authored-by: copilot-swe-agent[bot] <198982749+Copilot@users.noreply.github.com>
Co-authored-by: arnavsacheti <36746504+arnavsacheti@users.noreply.github.com>

---------

Co-authored-by: Copilot <198982749+Copilot@users.noreply.github.com>

tests/cocotb_lib/handle_utils.py

@@ -0,0 +1,69 @@
+"""Utilities for resolving cocotb signal handles across simulators."""
+
+from __future__ import annotations
+
+from typing import Any, Iterable
+
+
+class SignalHandle:
+    """
+    Wrapper that resolves array elements even when the simulator does not expose
+    unpacked arrays through ``handle[idx]``.
+    """
+
+    def __init__(self, dut, name: str) -> None:
+        self._dut = dut
+        self._name = name
+        self._base = getattr(dut, name, None)
+        self._cache: dict[tuple[int, ...], Any] = {}
+
+    def resolve(self, indices: tuple[int, ...]):
+        if not indices:
+            return self._base if self._base is not None else self._lookup(tuple())
+
+        if indices not in self._cache:
+            self._cache[indices] = self._direct_or_lookup(indices)
+        return self._cache[indices]
+
+    def _direct_or_lookup(self, indices: tuple[int, ...]):
+        if self._base is not None:
+            ref = self._base
+            try:
+                for idx in indices:
+                    ref = ref[idx]
+                return ref
+            except (IndexError, TypeError, AttributeError):
+                pass
+
+        return self._lookup(indices)
+
+    def _lookup(self, indices: tuple[int, ...]):
+        suffix = "".join(f"[{idx}]" for idx in indices)
+        path = f"{self._name}{suffix}"
+
+        try:
+            return getattr(self._dut, path)
+        except AttributeError:
+            pass
+
+        errors: list[Exception] = []
+        for extended in (False, True):
+            try:
+                return self._dut._id(path, extended=extended)
+            except (AttributeError, ValueError) as exc:
+                errors.append(exc)
+
+        raise AttributeError(f"Unable to resolve handle '{path}' via dut._id") from errors[-1]
+
+
+def resolve_handle(handle, indices: Iterable[int]):
+    """Resolve either a regular cocotb handle or a ``SignalHandle`` wrapper."""
+    index_tuple = tuple(indices)
+
+    if isinstance(handle, SignalHandle):
+        return handle.resolve(index_tuple)
+
+    ref = handle
+    for idx in index_tuple:
+        ref = ref[idx]
+    return ref