Consolidate all utility functions into chipflow_lib/utils.py

- Move compute_invert_mask() from platform/utils.py to main utils.py
- Delete chipflow_lib/platform/utils.py (now empty)
- Update imports in silicon.py and base.py to use main utils module
- All utility functions now in single location for better maintainability

Author: robtaylor

chipflow_lib/platform/base.py

@@ -10,7 +10,7 @@
 from amaranth import Module
 
 from .io import IOSignature
-from .utils import compute_invert_mask
+from ..utils import compute_invert_mask
 
 logger = logging.getLogger(__name__)
 

chipflow_lib/platform/silicon.py

@@ -20,10 +20,9 @@
 from amaranth.hdl import Fragment
 from amaranth.hdl._ir import PortDirection
 
-from ..utils import ChipFlowError
+from ..utils import ChipFlowError, compute_invert_mask
 from ..config import Process
 from .io import IOModel, IOTripPoint, Sky130DriveMode
-from .utils import compute_invert_mask
 
 if TYPE_CHECKING:
     from ..config import Config

chipflow_lib/platform/utils.py

@@ -104,6 +104,19 @@ def get_src_loc(src_loc_at: int = 0):
     return (frame.f_code.co_filename, frame.f_lineno)
 
 
+def compute_invert_mask(invert_list):
+    """
+    Compute a bit mask for signal inversion from a list of boolean invert flags.
+
+    Args:
+        invert_list: List of booleans indicating which bits should be inverted
+
+    Returns:
+        Integer mask where set bits indicate positions to invert
+    """
+    return sum(inv << bit for bit, inv in enumerate(invert_list))
+
+
 def top_components(config: 'Config') -> Dict[str, 'wiring.Component']:
     """
     Return the top level components for the design, as configured in ``chipflow.toml``.