the template/constexpr was a cool/dynamic swap version, but not needed. move to leverage the fast built in versions

Author: gigapod

src/sfeTk/sfeToolkit.cpp

@@ -24,6 +24,7 @@ CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
 */
 #include "sfeToolkit.h"
 
+//---------------------------------------------------------------------------------
 /**
  * @brief C function - Runtime check for system byte order
  */
@@ -32,3 +33,39 @@ sfeTKByteOrder sfeToolkit::systemByteOrder(void)
     uint16_t i = 1;
     return *((uint8_t *)&i) == 0 ? sfeTKByteOrder::BigEndian : sfeTKByteOrder::LittleEndian;
 }
+
+//---------------------------------------------------------------------------------
+/**
+ * @brief to catch 8 bit calls for byte swap
+ *
+ */
+uint8_t sfeToolkit::byte_swap(uint8_t i)
+{
+    return i;
+}
+//---------------------------------------------------------------------------------
+/**
+ * @brief function - Byte swap a 16 bit value
+ */
+uint16_t sfeToolkit::byte_swap(uint16_t i)
+{
+    // Use the fast intrinsic if available
+#if defined(__clang__) || defined(__GNUC__)
+    return __builtin_bswap16(i);
+#else
+    return (i << 8) | (i >> 8);
+#endif
+}
+
+//---------------------------------------------------------------------------------
+/**
+ * @brief function - Byte swap a 32 bit value
+ */
+uint32_t sfeToolkit::byte_swap(uint32_t i)
+{
+#if defined(__clang__) || defined(__GNUC__)
+    return __builtin_bswap32(i);
+#else
+    return ((i << 24) & 0xff000000) | ((i << 8) & 0x00ff0000) | ((i >> 8) & 0x0000ff00) | ((i >> 24) & 0x000000ff);
+#endif
+}

src/sfeTk/sfeToolkit.h

@@ -47,16 +47,8 @@ namespace sfeToolkit
 // Function to determine the byte order of the system
 sfeTKByteOrder systemByteOrder(void);
 
-// Method to swap the byte order of any unsigned integer - you pick the size. Uses constexpr so it's a compile time
-// operation/inline/optimized
-//
-// from
-// https://stackoverflow.com/questions/36936584/how-to-write-constexpr-swap-function-to-change-endianess-of-an-integer
-//
-template <class T>
-constexpr typename std::enable_if<std::is_unsigned<T>::value, T>::type byte_swap(T i, T j = 0u, std::size_t n = 0u)
-{
-    return n == sizeof(T) ? j : byte_swap<T>(i >> CHAR_BIT, (j << CHAR_BIT) | (i & (T)(unsigned char)(-1)), n + 1);
-}
+uint8_t byte_swap(uint8_t i);
+uint16_t byte_swap(uint16_t i);
+uint32_t byte_swap(uint32_t i);
 
 }; // namespace sfeToolkit