From: Luke Kenneth Casson Leighton <lkcl@lkcl.net>
Date: Sat, 9 May 2020 17:33:20 +0000 (+0100)
Subject: comment maskgen
X-Git-Tag: div_pipeline~1304
X-Git-Url: https://git.libre-soc.org/?a=commitdiff_plain;h=8c839e59991a8b0d56fa6a7c6b9fff6ba773d8f2;p=soc.git

comment maskgen
---

diff --git a/src/soc/alu/maskgen.py b/src/soc/alu/maskgen.py
index dd6b9573..89246e0b 100644
--- a/src/soc/alu/maskgen.py
+++ b/src/soc/alu/maskgen.py
@@ -2,6 +2,15 @@ from nmigen import (Elaboratable, Signal, Module)
 import math
 
 class MaskGen(Elaboratable):
+    """MaskGen - create a diff mask
+
+    example: x=5 --> a=0b11111
+             y=3 --> b=0b00111
+             o:        0b11000
+             x=2 --> a=0b00011
+             y=4 --> b=0b01111
+             o:        0b10011
+    """
     def __init__(self, width):
         self.width = width
         self.shiftwidth = math.ceil(math.log2(width))