From 07d712ea00d400a46c7480bcb4825590fb4c29c1 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?kleines=20Filmr=C3=B6llchen?= <filmroellchen@serenityos.org>
Date: Wed, 15 Jun 2022 21:34:25 +0200
Subject: [PATCH] AK: Add saturating addition and subtraction to Checked

---
 AK/Checked.h | 22 ++++++++++++++++++++++
 1 file changed, 22 insertions(+)

diff --git a/AK/Checked.h b/AK/Checked.h
index 5cf1d987f2..77d881273a 100644
--- a/AK/Checked.h
+++ b/AK/Checked.h
@@ -199,6 +199,28 @@ public:
         m_value /= other;
     }
 
+    constexpr void saturating_sub(T other)
+    {
+        sub(other);
+        // Depending on whether other was positive or negative, we have to saturate to min or max.
+        if (m_overflow && other <= 0)
+            m_value = NumericLimits<T>::max();
+        else if (m_overflow)
+            m_value = NumericLimits<T>::min();
+        m_overflow = false;
+    }
+
+    constexpr void saturating_add(T other)
+    {
+        add(other);
+        // Depending on whether other was positive or negative, we have to saturate to max or min.
+        if (m_overflow && other >= 0)
+            m_value = NumericLimits<T>::max();
+        else if (m_overflow)
+            m_value = NumericLimits<T>::min();
+        m_overflow = false;
+    }
+
     constexpr Checked& operator+=(Checked const& other)
     {
         m_overflow |= other.m_overflow;