module comments for popcount

diff --git a/src/soc/fu/logical/popcount.py b/src/soc/fu/logical/popcount.py
index d655b551f7ed463b3354bf6c93f3028915a157e7..e2a28207afb20910a157d54970e02e8fde1eac9f 100644 (file)
--- a/src/soc/fu/logical/popcount.py
+++ b/src/soc/fu/logical/popcount.py
@@ -1,5 +1,8 @@
-# Popcount
-from nmigen import (Elaboratable, Module, Signal, Cat, Mux, Const)
+# Popcount: a successive (cascading) sum-reduction algorithm starting from
+# single-bit adds and reducing down to one final answer: the total number of
+# bits set to "1" in the input.
+
+from nmigen import (Elaboratable, Module, Signal, Cat, Const)
 
 
 def array_of(count, bitwidth):