Use inlined example and update the expected output

Author: mborland

doc/modules/ROOT/pages/cfenv.adoc

@@ -57,55 +57,40 @@ rounding_mode fesetround(rounding_mode round) noexcept;
 
 IMPORTANT: Much like `std::fesetround`, `boost::decimal::fesetround` is not thread safe.
 
-Below is an example of the effects of changing the runtime rounding mode if your compiler supports it:
+[#examples_rounding_mode]
 
+.This https://github.com/cppalliance/decimal/blob/develop/examples/rounding_mode.cpp[example] demonstrates how to set, get, and effects of the global rounding mode.
+====
 [source, c++]
 ----
-#include <boost/decimal.hpp>
-#include <cassert>
-
-int main()
-{
-    using namespace boost::decimal::literals;
-
-    auto default_rounding_mode = boost::decimal::fegetround(); // Default is fe_dec_to_nearest
-
-    auto new_rounding_mode = boost::decimal::fesetround(boost::decimal::rounding_mode::fe_dec_upward);
-
-    assert(default_rounding_mode != new_rounding_mode);
-
-    const auto lhs {"5e+50"_DF};
-    const auto rhs {"4e+40"_DF};
-
-    // With upward rounding the result will be "5.000001e+50"_DF
-    // Even though the difference in order of magnitude is greater than the precision of the type,
-    // any addition in this mode will result in at least a one ULP difference
-    const auto upward_res {lhs + rhs};
-    assert(upward_res == "5.000001e+50"_DF);
-
-    boost::decimal::fesetround(boost::decimal::rounding_mode::fe_dec_downward);
-
-    // Similar to above in the downward rounding mode any subtraction will result in at least a one ULP difference
-    const auto downward_res {lhs - rhs};
-    assert(downward_res == "4.999999e+50"_DF);
-
-    return 0;
-}
+include::example$rounding_mode.cpp[]
 ----
 
+.Expected Output:
+....
+The default rounding mode is: fe_dec_to_nearest
+The current rounding mode is: fe_dec_upward
+lhs equals: 5e+50
+rhs equals: 4e+40
+  Sum with upward rounding: 5.000001e+50
+The current rounding mode is: fe_dec_downward
+Sum with downward rounding: 4.999999e+50
+....
+====
+
 As shown, changing the rounding mode *WILL* change your numerical results.
 If you are coming from the Intel library (or other C-style libs) where every mathematical function takes a rounding mode, that is not the case in this library; the only way to change the rounding mode for individual operations is via the global rounding mode.
 Before attempting to change the rounding mode ensure this is actually what you want to happen.
 
 You can similarly change the default rounding mode at compile time with *ANY* compiler (unlike at runtime) using similarly named macros:
 
-1. BOOST_DECIMAL_FE_DEC_DOWNWARD
-2. BOOST_DECIMAL_FE_DEC_TO_NEAREST
-3. BOOST_DECIMAL_FE_DEC_TO_NEAREST_FROM_ZERO
-4. BOOST_DECIMAL_FE_DEC_TOWARD_ZERO
-5. BOOST_DECIMAL_FE_DEC_UPWARD
+1. `BOOST_DECIMAL_FE_DEC_DOWNWARD`
+2. `BOOST_DECIMAL_FE_DEC_TO_NEAREST`
+3. `BOOST_DECIMAL_FE_DEC_TO_NEAREST_FROM_ZERO`
+4. `BOOST_DECIMAL_FE_DEC_TOWARD_ZERO`
+5. `BOOST_DECIMAL_FE_DEC_UPWARD`
 
-If none of the above macros are defined, the default rounding mode for compile time is the same as the default runtime (i.e. as if BOOST_DECIMAL_FE_DEC_TO_NEAREST were defined).
+If none of the above macros are defined, the default rounding mode for compile time is the same as the default runtime (i.e. as if `BOOST_DECIMAL_FE_DEC_TO_NEAREST` were defined).
 At most *ONE* of these macros are allowed to be user defined.
 A `#error` will be emitted if more than one is detected.
 The macro must be defined before the inclusion of any decimal library header.
@@ -117,22 +102,16 @@ This same example can be reduced for the cases where:
 
 2. You want to change the compile time rounding mode
 
+.This https://github.com/cppalliance/decimal/blob/develop/examples/rounding_mode.cpp[example] demonstrates how the compile time rounding mode can be set, and it's effects on compile time and run time evaluation.
+====
 [source, c++]
 ----
-#define BOOST_DECIMAL_FE_DEC_DOWNWARD
-#include <boost/decimal.hpp>
-
-int main()
-{
-    using namespace boost::decimal::literals;
-
-    constexpr auto lhs {"5e+50"_DF};
-    constexpr auto rhs {"4e+40"_DF};
-    constexpr auto downward_res {lhs - rhs};
-    static_assert(downward_res == "4.999999e+50"_DF, "Incorrectly rounded result");
-
-    return 0;
-}
+include::example$rounding_mode_compile_time.cpp[]
 ----
 
+.Expected Output
+....
+....
+====
+
 IMPORTANT: Prior to v5.2.0 this header was `<boost/decimal/fenv.hpp>`, but has been changed to `<boost/decimal/cfenv.hpp>` for consistency with the STL naming convention.