add masked util function

diff --git a/src/nmutil/mask.py b/src/nmutil/mask.py
index 223752297e0d48ffeffc23f3c6ca02280270c13e..25fd1429d94921b9453de863a92914fd8fa8027b 100644 (file)
--- a/src/nmutil/mask.py
+++ b/src/nmutil/mask.py
@@ -1,6 +1,9 @@
 from nmigen import Module, Signal, Elaboratable
 from nmigen.utils import log2_int
 
+def masked(m_out, m_in, mask):
+    return (m_out & ~mask) | (m_in & mask)
+
 
 class Mask(Elaboratable):
     def __init__(self, sz):