From: Sergey Matveev <stargrave@stargrave.org>
Date: Tue, 31 May 2022 13:16:04 +0000 (+0300)
Subject: Simpler and slightly faster 512-bit-addition code
X-Git-Tag: 5.12~8
X-Git-Url: http://www.git.cypherpunks.ru/?p=pygost.git;a=commitdiff_plain;h=d7cf18d77f96e9a69cde610523e7a84efc8bc76a

Simpler and slightly faster 512-bit-addition code
---

diff --git a/pygost/gost34112012.py b/pygost/gost34112012.py
index f1a7acc..48d7ae2 100644
--- a/pygost/gost34112012.py
+++ b/pygost/gost34112012.py
@@ -184,16 +184,10 @@ LCache = _lcache()
 
 
 def add512bit(a, b):
-    """Add two 512 integers
-    """
-    a = bytearray(a)
-    b = bytearray(b)
-    cb = 0
-    res = bytearray(64)
-    for i in range(64):
-        cb = a[i] + b[i] + (cb >> 8)
-        res[i] = cb & 0xff
-    return res
+    a = int.from_bytes(a, "little")
+    b = int.from_bytes(b, "little")
+    r = (a + b) % (1 << 512)
+    return r.to_bytes(512 // 8, "little")
 
 
 def g(n, hsh, msg):