From: Michael Nolan <mtnolan2640@gmail.com>
Date: Mon, 30 Mar 2020 23:57:14 +0000 (-0400)
Subject: Add more comments to helpers.py
X-Git-Tag: div_pipeline~1586
X-Git-Url: https://git.libre-soc.org/?a=commitdiff_plain;h=4dcce6d901255043bd660c94dc82ba5406ae73c0;p=soc.git

Add more comments to helpers.py
---

diff --git a/src/soc/decoder/helpers.py b/src/soc/decoder/helpers.py
index 95aa2852..79660d45 100644
--- a/src/soc/decoder/helpers.py
+++ b/src/soc/decoder/helpers.py
@@ -34,6 +34,12 @@ def MASK(x, y):
     return mask_a ^ mask_b
 
 
+# For these tests I tried to find power instructions that would let me
+# isolate each of these helper operations. So for instance, when I was
+# testing the MASK() function, I chose rlwinm and rldicl because if I
+# set the shift equal to 0 and passed in a value of all ones, the
+# result I got would be exactly the same as the output of MASK()
+
 class HelperTests(unittest.TestCase):
     def test_MASK(self):
         # Verified using rlwinm, rldicl, rldicr in qemu
@@ -79,8 +85,11 @@ class HelperTests(unittest.TestCase):
         value_b = 0x73123456 # r2
         value_c = 0x80000000 # r3
 
+        # extswsli reg, 1, 0
         self.assertHex(EXTS64(value_a), 0xffffffffdeadbeef)
+        # extswsli reg, 2, 0
         self.assertHex(EXTS64(value_b), value_b)
+        # extswsli reg, 3, 0
         self.assertHex(EXTS64(value_c), 0xffffffff80000000)