From d05ae67708ec9db54f90ef11292c38ca5c9dba5f Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Max=20L=C3=BCbke?= <mluebke@gfz-potsdam.de>
Date: Thu, 23 Nov 2023 15:47:38 +0100
Subject: [PATCH] Add simple fixed point type

---
 include/tug/Datatypes/FixedPoint.hpp | 98 ++++++++++++++++++++++++++++
 test/CMakeLists.txt                  |  3 +
 test/testFixedPoint.cpp              | 35 ++++++++++
 3 files changed, 136 insertions(+)
 create mode 100644 include/tug/Datatypes/FixedPoint.hpp
 create mode 100644 test/testFixedPoint.cpp

diff --git a/include/tug/Datatypes/FixedPoint.hpp b/include/tug/Datatypes/FixedPoint.hpp
new file mode 100644
index 0000000..2ecf0fa
--- /dev/null
+++ b/include/tug/Datatypes/FixedPoint.hpp
@@ -0,0 +1,98 @@
+#ifndef TUG_FIXED_TYPE
+#define TUG_FIXED_TYPE
+
+#include <cstdint>
+#include <ostream>
+#include <type_traits>
+
+namespace tug {
+
+template <typename BaseType, typename GreaterType, unsigned int FractionBits,
+          unsigned int IntegerMult = BaseType(1) << FractionBits>
+class FixedPoint {
+public:
+  // zero init
+  constexpr FixedPoint() : _internal_value(0) {}
+
+  // construct a fixed point from value
+  template <typename T>
+  constexpr FixedPoint(T val)
+      : _internal_value(static_cast<BaseType>(val * IntegerMult)) {}
+
+  // cast a fixed point to a data type
+  template <typename T> constexpr operator T() const {
+    return static_cast<T>(static_cast<T>(_internal_value) / IntegerMult);
+  }
+
+  // addition
+  template <typename T> constexpr FixedPoint operator+(const T &rhs) const {
+    return FixedPoint(add(this->_internal_value, rhs), {});
+  }
+
+  // subtraction
+  template <typename T> constexpr FixedPoint operator-(const T &rhs) const {
+    return FixedPoint(sub(this->_internal_value, rhs), {});
+  }
+
+  // multiplication
+  template <typename T> constexpr FixedPoint operator*(const T &rhs) const {
+    return FixedPoint(mul(this->_internal_value, rhs), {});
+  }
+
+  // division
+  template <typename T> constexpr FixedPoint operator/(const T &rhs) const {
+    return FixedPoint(div(this->_internal_value, rhs), {});
+  }
+
+  // equality
+  template <typename T> constexpr bool operator==(const T &rhs) const {
+    return eq(this->_internal_value, rhs);
+  }
+
+private:
+  struct placeholder {};
+  constexpr FixedPoint(BaseType _val, placeholder) : _internal_value(_val) {}
+
+  static constexpr BaseType add(const BaseType _lhs, const FixedPoint _rhs) {
+    return static_cast<BaseType>(_lhs + _rhs._internal_value);
+  }
+
+  static constexpr BaseType sub(const BaseType _lhs, const FixedPoint _rhs) {
+    return static_cast<BaseType>(_lhs - _rhs._internal_value);
+  }
+
+  static constexpr BaseType mul(const BaseType _lhs, const FixedPoint _rhs) {
+    return static_cast<BaseType>(
+        static_cast<GreaterType>(_lhs * _rhs._internal_value) / IntegerMult);
+  }
+
+  static constexpr BaseType div(const BaseType _lhs, const FixedPoint _rhs) {
+    return static_cast<BaseType>(static_cast<GreaterType>(_lhs * IntegerMult) /
+                                 _rhs._internal_value);
+  }
+
+  static constexpr bool eq(const BaseType _lhs, const FixedPoint _rhs) {
+    return _lhs == _rhs._internal_value;
+  }
+
+  BaseType _internal_value;
+};
+
+template <typename B, typename G, unsigned int F>
+std::ostream &operator<<(std::ostream &os, const FixedPoint<B, G, F> &fp) {
+  os << static_cast<double>(fp);
+
+  return os;
+}
+
+template <unsigned int F>
+using Fixed32 = FixedPoint<std::int32_t, std::int64_t, F>;
+
+template <unsigned int F>
+using Fixed16 = FixedPoint<std::int16_t, std::int32_t, F>;
+
+template <unsigned int F>
+using Fixed8 = FixedPoint<std::int8_t, std::int16_t, F>;
+} // namespace tug
+
+#endif // TUG_FIXED_TYPE
\ No newline at end of file
diff --git a/test/CMakeLists.txt b/test/CMakeLists.txt
index 19c4daf..aaae1d9 100644
--- a/test/CMakeLists.txt
+++ b/test/CMakeLists.txt
@@ -25,3 +25,6 @@ add_custom_target(
   check
   COMMAND $<TARGET_FILE:testTug>
   DEPENDS testTug)
+
+add_executable(fixed_point testFixedPoint.cpp)
+target_link_libraries(fixed_point PRIVATE tug)
\ No newline at end of file
diff --git a/test/testFixedPoint.cpp b/test/testFixedPoint.cpp
new file mode 100644
index 0000000..9136b84
--- /dev/null
+++ b/test/testFixedPoint.cpp
@@ -0,0 +1,35 @@
+#include "tug/Datatypes/FixedPoint.hpp"
+
+#include <cstdint>
+#include <iostream>
+
+using namespace tug;
+
+using FPToTest = Fixed8<5>;
+
+int main() {
+  FPToTest with(1.5);
+  FPToTest without(0.5);
+
+  const int test = 0;
+
+  const FPToTest lol = 0;
+
+  if (lol == test) {
+    std::cout << "This works\n";
+  }
+
+  double operation;
+
+  operation = with + without;
+  std::cout << "Addition: " << operation << std::endl;
+
+  operation = with - without;
+  std::cout << "Subtraction: " << operation << std::endl;
+
+  operation = with * without;
+  std::cout << "Mult: " << operation << std::endl;
+
+  operation = with / without;
+  std::cout << "Div: " << operation << std::endl;
+}
\ No newline at end of file