From 91c454b7ff757feff03ad0253b7ef8ffa0096688 Mon Sep 17 00:00:00 2001
From: Vladislav Shchapov <phprus@gmail.com>
Date: Thu, 28 Oct 2021 21:15:41 +0500
Subject: [PATCH] Performance improvement

---
 include/fmt/chrono.h | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/include/fmt/chrono.h b/include/fmt/chrono.h
index 0ac173ff..874dc4d9 100644
--- a/include/fmt/chrono.h
+++ b/include/fmt/chrono.h
@@ -1459,8 +1459,9 @@ template <typename OutputIt, typename Char> class tm_writer {
   }
 
   auto tm_hour12() const noexcept -> int {
-    auto hour = tm_hour() % 12;
-    return hour == 0 ? 12 : hour;
+    const auto h = tm_hour();
+    const auto z = h < 12 ? h : h - 12;
+    return z == 0 ? 12 : z;
   }
 
   // POSIX and the C Standard are unclear or inconsistent about what %C and %y