Ensure we have at least one master

diff --git a/gram/core/crossbar.py b/gram/core/crossbar.py
index 70d2afbad36d955f80139f2e4df08acb20e14b84..66301a36d8abd32140455b8acdadb1739d90cfc7 100644 (file)
--- a/gram/core/crossbar.py
+++ b/gram/core/crossbar.py
@@ -133,6 +133,7 @@ class gramCrossbar(Elaboratable):
 
         controller = self.controller
         nmasters = len(self.masters)
+        assert nmasters > 0
 
         # Address mapping --------------------------------------------------------------------------
         cba_shifts = {