[util] Implement simplest ratio helper

src/util/util_ratio.h

@@ -0,0 +1,81 @@
+#include <numeric>
+#include <algorithm>
+#include <cstdint>
+#include <string>
+#include <charconv>
+
+namespace dxvk {
+
+  /**
+   * \brief Simplest ratio helper
+   */
+  template <typename T>
+  class Ratio {
+
+  public:
+
+    Ratio(T num, T denom) {
+      set(num, denom);
+    }
+
+    Ratio(std::string_view view) {
+      set(0, 0);
+
+      size_t colon = view.find(":");
+
+      if (colon == std::string_view::npos)
+        return;
+
+      std::string_view numStr   = view.substr(0, colon);
+      std::string_view denomStr = view.substr(colon + 1);
+
+      T num = 0, denom = 0;
+      std::from_chars(numStr.data(),   numStr.data()   + numStr.size(),   num);
+      std::from_chars(denomStr.data(), denomStr.data() + denomStr.size(), denom);
+
+      set(num, denom);
+    }
+
+    inline T num()    const { return m_num; }
+    inline T denom() const { return m_denom; }
+
+    inline bool undefined() const { return m_denom == 0; }
+
+    inline void set(T num, T denom) {
+      const T gcd = std::gcd(num, denom);
+
+      m_num = num / gcd;
+      m_denom = denom / gcd;
+    }
+
+    inline bool operator == (const Ratio& other) const {
+      return num() == other.num() && denom() == other.denom();
+    }
+
+    inline bool operator != (const Ratio& other) const {
+      return !(*this == other);
+    }
+
+    inline bool operator >= (const Ratio& other) const {
+      return num() * other.denom() >= other.num() * denom();
+    }
+
+    inline bool operator > (const Ratio& other) const {
+      return num() * other.denom() > other.num() * denom();
+    }
+
+    inline bool operator < (const Ratio& other) const {
+      return  !(*this >= other);
+    }
+
+    inline bool operator <= (const Ratio& other) const {
+      return  !(*this > other);
+    }
+
+  private:
+
+    T m_num, m_denom;
+
+  };
+
+}