replace custom gcd function with std

Signed-off-by: Rosen Penev <rosenp@gmail.com>

include/exiv2/types.hpp

@@ -506,45 +506,6 @@ T stringTo(const std::string& s, bool& ok) {
 template <>
 bool stringTo<bool>(const std::string& s, bool& ok);
 
-/*!
-  @brief Return the greatest common denominator of n and m.
-         (Implementation from Boost rational.hpp)
-
-  @note We use n and m as temporaries in this function, so there is no
-        value in using const IntType& as we would only need to make a copy
-        anyway...
- */
-template <typename IntType>
-IntType gcd(IntType n, IntType m) {
-  // Avoid repeated construction
-  IntType zero(0);
-
-  // This is abs() - given the existence of broken compilers with Koenig
-  // lookup issues and other problems, I code this explicitly. (Remember,
-  // IntType may be a user-defined type).
-  if (n < zero) {
-    if (n == std::numeric_limits<IntType>::min()) {
-      n = std::numeric_limits<IntType>::max();
-    } else {
-      n = -n;
-    }
-  }
-  if (m < zero)
-    m = -m;
-
-  // As n and m are now positive, we can be sure that %= returns a
-  // positive value (the standard guarantees this for built-in types,
-  // and we require it of user-defined types).
-  for (;;) {
-    if (m == zero)
-      return n;
-    n %= m;
-    if (n == zero)
-      return m;
-    m %= n;
-  }
-}
-
 }  // namespace Exiv2
 
 #endif  // #ifndef TYPES_HPP_

src/tags_int.cpp

@@ -22,6 +22,7 @@
 
 #include <algorithm>
 #include <cmath>
+#include <numeric>
 
 // *****************************************************************************
 // local declarations
@@ -2807,7 +2808,7 @@ std::ostream& print0x9204(std::ostream& os, const Value& value, const ExifData*)
   } else if (bias.second <= 0) {
     os << "(" << bias.first << "/" << bias.second << ")";
   } else {
-    int32_t d = gcd(bias.first, bias.second);
+    int32_t d = std::gcd(bias.first, bias.second);
     int32_t num = std::abs(bias.first) / d;
     int32_t den = bias.second / d;
     os << (bias.first < 0 ? "-" : "+") << num;

src/types.cpp

@@ -15,6 +15,7 @@
 #include <cmath>
 #include <cstring>
 #include <iomanip>
+#include <numeric>
 #include <sstream>
 #include <utility>
 
@@ -629,7 +630,7 @@ Rational floatToRationalCast(float f) {
     den = 10000;
   }
   const auto nom = static_cast<int32_t>(std::round(d * den));
-  const int32_t g = gcd(nom, den);
+  const int32_t g = std::gcd(nom, den);
 
   return {nom / g, den / g};
 }