From a58121e893e1753c7011d25893918b4419a04457 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Vladim=C3=ADr=20Vondru=C5=A1?= <mosra@centrum.cz>
Date: Fri, 3 Apr 2015 23:39:49 +0200
Subject: [PATCH] Math: added div() function.

---
 src/Magnum/Math/Functions.h            | 20 ++++++++++++++++++++
 src/Magnum/Math/Test/FunctionsTest.cpp | 10 ++++++++++
 2 files changed, 30 insertions(+)

diff --git a/src/Magnum/Math/Functions.h b/src/Magnum/Math/Functions.h
index c6e7ae14e..4ccb2db1b 100644
--- a/src/Magnum/Math/Functions.h
+++ b/src/Magnum/Math/Functions.h
@@ -79,6 +79,26 @@ UnsignedInt MAGNUM_EXPORT log2(UnsignedInt number);
  */
 UnsignedInt MAGNUM_EXPORT log(UnsignedInt base, UnsignedInt number);
 
+/**
+@brief Integer division with remainder
+
+Example usage:
+@code
+Int quotient, remainder;
+std::tie(quotient, remainder) = Math::div(57, 6); // {9, 3}
+@endcode
+Equivalent to the following, but possibly done in a single CPU instruction:
+@code
+Int quotient = 57/6;
+Int remainder = 57%6;
+@endcode
+*/
+template<class Integral> std::pair<Integral, Integral> div(Integral x, Integral y) {
+    static_assert(std::is_integral<Integral>{}, "Math::div(): not an integral type");
+    const auto result = std::div(x, y);
+    return {result.quot, result.rem};
+}
+
 /** @todo Can't trigonometric functions be done with only one overload? */
 
 /** @brief Sine */
diff --git a/src/Magnum/Math/Test/FunctionsTest.cpp b/src/Magnum/Math/Test/FunctionsTest.cpp
index 564bff971..95b71cbee 100644
--- a/src/Magnum/Math/Test/FunctionsTest.cpp
+++ b/src/Magnum/Math/Test/FunctionsTest.cpp
@@ -23,6 +23,7 @@
     DEALINGS IN THE SOFTWARE.
 */
 
+#include <tuple>
 #include <Corrade/TestSuite/Tester.h>
 
 #include "Magnum/Math/Functions.h"
@@ -65,6 +66,7 @@ struct FunctionsTest: Corrade::TestSuite::Tester {
     void pow();
     void log();
     void log2();
+    void div();
     void trigonometric();
     void trigonometricWithBase();
 };
@@ -111,6 +113,7 @@ FunctionsTest::FunctionsTest() {
               &FunctionsTest::pow,
               &FunctionsTest::log,
               &FunctionsTest::log2,
+              &FunctionsTest::div,
               &FunctionsTest::trigonometric,
               &FunctionsTest::trigonometricWithBase});
 }
@@ -410,6 +413,13 @@ void FunctionsTest::log2() {
     CORRADE_COMPARE(Math::log2(2153), 11);
 }
 
+void FunctionsTest::div() {
+    Int quotient, remainder;
+    std::tie(quotient, remainder) = Math::div(57, 6);
+    CORRADE_COMPARE(quotient, 9);
+    CORRADE_COMPARE(remainder, 3);
+}
+
 void FunctionsTest::trigonometric() {
     CORRADE_COMPARE(Math::sin(Deg(30.0f)), 0.5f);
     CORRADE_COMPARE(Math::sin(Rad(Constants::pi()/6)), 0.5f);