From 501183ca3e33283d6429ebff17eff28cea8c34b9 Mon Sep 17 00:00:00 2001
From: Simon Rozman <simon@rozman.si>
Date: Thu, 17 Aug 2023 12:56:13 +0200
Subject: [PATCH] math: add

Signed-off-by: Simon Rozman <simon@rozman.si>
---
 UnitTests/UnitTests.vcxproj         |  1 +
 UnitTests/UnitTests.vcxproj.filters |  3 ++
 UnitTests/math.cpp                  | 42 +++++++++++++++++++++++++
 UnitTests/pch.h                     |  1 +
 include/stdex/math.hpp              | 49 +++++++++++++++++++++++++++++
 5 files changed, 96 insertions(+)
 create mode 100644 UnitTests/math.cpp
 create mode 100644 include/stdex/math.hpp

diff --git a/UnitTests/UnitTests.vcxproj b/UnitTests/UnitTests.vcxproj
index b6cd49e05..cdc137988 100644
--- a/UnitTests/UnitTests.vcxproj
+++ b/UnitTests/UnitTests.vcxproj
@@ -116,6 +116,7 @@
   <ItemDefinitionGroup Condition="'$(Configuration)|$(Platform)'=='Release|x64'" />
   <ItemGroup>
     <ClCompile Include="ios.cpp" />
+    <ClCompile Include="math.cpp" />
     <ClCompile Include="parser.cpp" />
     <ClCompile Include="pch.cpp">
       <PrecompiledHeader>Create</PrecompiledHeader>
diff --git a/UnitTests/UnitTests.vcxproj.filters b/UnitTests/UnitTests.vcxproj.filters
index 05a4e21ce..a1d5947e6 100644
--- a/UnitTests/UnitTests.vcxproj.filters
+++ b/UnitTests/UnitTests.vcxproj.filters
@@ -27,6 +27,9 @@
     <ClCompile Include="ios.cpp">
       <Filter>Source Files</Filter>
     </ClCompile>
+    <ClCompile Include="math.cpp">
+      <Filter>Source Files</Filter>
+    </ClCompile>
   </ItemGroup>
   <ItemGroup>
     <ClInclude Include="pch.h">
diff --git a/UnitTests/math.cpp b/UnitTests/math.cpp
new file mode 100644
index 000000000..9975c3dd6
--- /dev/null
+++ b/UnitTests/math.cpp
@@ -0,0 +1,42 @@
+/*
+	SPDX-License-Identifier: MIT
+	Copyright © 2023 Amebis
+*/
+
+#include "pch.h"
+
+using namespace std;
+using namespace Microsoft::VisualStudio::CppUnitTestFramework;
+
+namespace UnitTests
+{
+	TEST_CLASS(math)
+	{
+	public:
+		TEST_METHOD(mul)
+		{
+			Assert::AreEqual<size_t>(10, stdex::mul(2, 5));
+			Assert::AreEqual<size_t>(10, stdex::mul(5, 2));
+			Assert::AreEqual<size_t>(0, stdex::mul(0, 10));
+			Assert::AreEqual<size_t>(0, stdex::mul(10, 0));
+			Assert::AreEqual<size_t>(0, stdex::mul(SIZE_MAX, 0));
+			Assert::AreEqual<size_t>(0, stdex::mul(0, SIZE_MAX));
+			Assert::AreEqual<size_t>(SIZE_MAX, stdex::mul(SIZE_MAX, 1));
+			Assert::AreEqual<size_t>(SIZE_MAX, stdex::mul(1, SIZE_MAX));
+			Assert::ExpectException<std::invalid_argument>([] { stdex::mul(SIZE_MAX, 2); });
+			Assert::ExpectException<std::invalid_argument>([] { stdex::mul(2, SIZE_MAX); });
+		}
+
+		TEST_METHOD(add)
+		{
+			Assert::AreEqual<size_t>(7, stdex::add(2, 5));
+			Assert::AreEqual<size_t>(7, stdex::add(5, 2));
+			Assert::AreEqual<size_t>(10, stdex::add(0, 10));
+			Assert::AreEqual<size_t>(10, stdex::add(10, 0));
+			Assert::AreEqual<size_t>(SIZE_MAX, stdex::add(SIZE_MAX, 0));
+			Assert::AreEqual<size_t>(SIZE_MAX, stdex::add(0, SIZE_MAX));
+			Assert::ExpectException<std::invalid_argument>([] { stdex::add(SIZE_MAX, 1); });
+			Assert::ExpectException<std::invalid_argument>([] { stdex::add(1, SIZE_MAX); });
+		}
+	};
+}
diff --git a/UnitTests/pch.h b/UnitTests/pch.h
index 6016f700e..b7d7f5037 100644
--- a/UnitTests/pch.h
+++ b/UnitTests/pch.h
@@ -16,6 +16,7 @@
 #include <stdex/interval.hpp>
 #include <stdex/ios.hpp>
 #include <stdex/mapping.hpp>
+#include <stdex/math.hpp>
 #include <stdex/parser.hpp>
 #include <stdex/progress.hpp>
 #include <stdex/sal.hpp>
diff --git a/include/stdex/math.hpp b/include/stdex/math.hpp
new file mode 100644
index 000000000..73427a34d
--- /dev/null
+++ b/include/stdex/math.hpp
@@ -0,0 +1,49 @@
+/*
+	SPDX-License-Identifier: MIT
+	Copyright © 2023 Amebis
+*/
+
+#pragma once
+
+#include "sal.hpp"
+#include "system.hpp"
+#include <stdexcept>
+
+namespace stdex
+{
+	inline size_t mul(size_t a, size_t b)
+	{
+#if _MSC_VER >= 1300
+		SIZE_T result;
+		if (SUCCEEDED(SIZETMult(a, b, &result)))
+			return result;
+#elif defined(_MSC_VER)
+		if (a == 0)
+			return 0;
+		if (b <= SIZE_MAX / a)
+			return a * b;
+#else
+		size_t result;
+		if (!__builtin_mul_overflow(a, b, &result))
+			return result;
+#endif
+		throw std::invalid_argument("multiply overflow");
+	}
+
+	inline size_t add(size_t a, size_t b)
+	{
+#if _MSC_VER >= 1300
+		SIZE_T result;
+		if (SUCCEEDED(SIZETAdd(a, b, &result)))
+			return result;
+#elif defined(_MSC_VER)
+		if (a <= SIZE_MAX - b)
+			return a + b;
+#else
+		size_t result;
+		if (!__builtin_add_overflow(a, b, &result))
+			return result;
+#endif
+		throw std::invalid_argument("add overflow");
+	}
+}
\ No newline at end of file