From: Loup Vaillant <loup@loup-vaillant.fr>
Date: Thu, 16 Apr 2020 17:52:50 +0000 (+0200)
Subject: Worked around Microsoft compiler warning
X-Git-Url: https://git.codecow.com/?a=commitdiff_plain;h=2628471a1991b619b9f34b515ffab43781b7f25b;p=Monocypher.git

Worked around Microsoft compiler warning

Fixes #169

MSVC issues a warning when we try to negate an unsigned number.  The goal
however was to perform bit twiddling, so I used bitwise negation.
Hopefully the compiler will not complain about overflow, which is
perfectly well defined on unsigned numbers.
---

diff --git a/src/monocypher.c b/src/monocypher.c
index 253643e..a89193c 100644
--- a/src/monocypher.c
+++ b/src/monocypher.c
@@ -2667,7 +2667,7 @@ static void redc(u32 u[8], u32 x[16])
         carry  += (u64)t[i+8] + ~l[i];
         carry >>= 32;
     }
-    u32 mask = (u32)-carry; // carry == 0 or 1
+    u32 mask = ~(u32)carry + 1; // carry == 0 or 1
     FOR (i, 0, 8) {
         carry  += (u64)t[i+8] + (~l[i] & mask);
         u[i]    = (u32)carry;