feat: Add support for SKY130 OpenRAM SRAM integration

- Introduced  to handle the preparation of the SKY130 OpenRAM SRAM views.
- Updated  to download and prepare the SRAM archive during PDK setup.
- Enhanced OpenSTA and Yosys configurations to accommodate SRAM macro integration.
- Added Verilog simulation models for GF180 and SKY130 SRAM macros.
- Implemented tests for SRAM setup and validation, ensuring correct integration and functionality.
- Updated various Makefiles and scripts to support SRAM size and macro configurations.

tests/test_sky130_sram_setup.py

@@ -0,0 +1,76 @@
+"""Tests for the locked SKY130 OpenRAM SRAM setup path."""
+
+from __future__ import annotations
+
+import hashlib
+import io
+import json
+import tarfile
+from pathlib import Path
+
+import pytest
+
+from physical.pdk.prepare_sky130_sram import (
+    EXPECTED_CORNERS,
+    EXPECTED_GEOMETRY,
+    INPUT_CONFIG_SHA256,
+    MACRO,
+    OPENRAM_COMMIT,
+    REQUIRED_FILES,
+    SKY130_BUILDSPACE_REVISION,
+    SKY130_CIEL_REVISION,
+    prepare,
+)
+
+
+def make_archive(path: Path, *, corners: list[str] | None = None) -> str:
+    payloads = {
+        name: f"generated {name}\n".encode()
+        for name in REQUIRED_FILES
+        if name not in {"manifest.json", "SHA256SUMS"}
+    }
+    manifest = {
+        "schema_version": 1,
+        "macro": MACRO,
+        "geometry": EXPECTED_GEOMETRY,
+        "corners": EXPECTED_CORNERS if corners is None else corners,
+        "openram_commit": OPENRAM_COMMIT,
+        "input_config_sha256": INPUT_CONFIG_SHA256,
+        "sky130_ciel_revision": SKY130_CIEL_REVISION,
+        "sky130_buildspace_revision": SKY130_BUILDSPACE_REVISION,
+        "analytical_characterization": True,
+        "drc_lvs_checked": False,
+        "files": {
+            name: hashlib.sha256(content).hexdigest() for name, content in payloads.items()
+        },
+    }
+    payloads["manifest.json"] = (json.dumps(manifest) + "\n").encode()
+    payloads["SHA256SUMS"] = b"fixture checksums\n"
+    with tarfile.open(path, "w:gz") as archive:
+        for name, content in payloads.items():
+            member = tarfile.TarInfo(name)
+            member.size = len(content)
+            archive.addfile(member, io.BytesIO(content))
+    return hashlib.sha256(path.read_bytes()).hexdigest()
+
+
+def test_prepare_sky130_sram_is_verified_and_idempotent(tmp_path: Path) -> None:
+    archive = tmp_path / "sram.tar.gz"
+    digest = make_archive(archive)
+    output = tmp_path / "openram"
+
+    prepare(archive, output, digest)
+    first_mtime = (output / ".complete").stat().st_mtime_ns
+    prepare(archive, output, digest)
+
+    assert (output / f"{MACRO}.v").is_file()
+    assert (output / ".complete").read_text(encoding="utf-8").strip() == digest
+    assert (output / ".complete").stat().st_mtime_ns == first_mtime
+
+
+def test_prepare_sky130_sram_rejects_wrong_corners(tmp_path: Path) -> None:
+    archive = tmp_path / "sram.tar.gz"
+    digest = make_archive(archive, corners=["TT_1p8V_25C"])
+
+    with pytest.raises(RuntimeError, match="corners"):
+        prepare(archive, tmp_path / "openram", digest)