tb: Move BIT to util

This function may be useful for other testbenches.

Signed-off-by: Sean Anderson <seanga2@gmail.com>

tb/mdio_regs.py

@@ -6,8 +6,7 @@ from cocotb.clock import Clock
 from cocotb.triggers import FallingEdge, Timer
 from cocotb.types import LogicArray
 
-def BIT(n):
-    return 1 << n
+from .util import BIT
 
 BMCR = 0
 BMSR = 1

tb/util.py

@@ -16,6 +16,9 @@ async def async_iter(it):
     for i in it:
         yield i
 
+def BIT(n):
+    return 1 << n
+
 # From https://stackoverflow.com/a/7864317/5086505
 class classproperty(property):
     def __get__(self, cls, owner):