From: Tim 'mithro' Ansell <me@mith.ro>
Date: Thu, 29 Nov 2018 04:18:31 +0000 (-0800)
Subject: Only write file if contents will change.
X-Git-Tag: 24jan2021_ls180~1029^2
X-Git-Url: https://git.libre-soc.org/?a=commitdiff_plain;h=3ff6a18a45ff4840530d97cd1f6d97e7596afeb5;p=litex.git

Only write file if contents will change.
---

diff --git a/litex/build/tools.py b/litex/build/tools.py
index 28e1937d..81326201 100644
--- a/litex/build/tools.py
+++ b/litex/build/tools.py
@@ -28,8 +28,13 @@ def write_to_file(filename, contents, force_unix=False):
     newline = None
     if force_unix:
         newline = "\n"
-    with open(filename, "w", newline=newline) as f:
-        f.write(contents)
+    old_contents = None
+    if os.path.exists(filename):
+        with open(filename, "r", newline=newline) as f:
+            old_contents = f.read()
+    if old_contents != contents:
+        with open(filename, "w", newline=newline) as f:
+            f.write(contents)
 
 
 def arch_bits():