dpx: use OIIO functions for byte swapping to make Sonar happy

src/dpx.imageio/dpxinput.cpp

@@ -10,6 +10,17 @@
 
 // Note: libdpx originally from: https://github.com/PatrickPalmer/dpx
 // But that seems not to be actively maintained.
+//
+// Nevertheless, because the contents of the libdpx subdirectory is "imported"
+// code, we have always strived to keep our copy as textually close to the
+// original as possible, to enable us to diff it against the original and keep
+// up with any changes (if there ever are any). So we exclude this file from
+// clang-format and try to keep changes as minimal as possible.
+//
+// At some point, we may want to consider just accepting that we forked long
+// ago and are probably the sole maintainers of this code, and just allow
+// ourselves to diverge from the original.
+
 #include "libdpx/DPX.h"
 #include "libdpx/DPXColorConverter.h"
 #include "libdpx/DPXHeader.h"

src/dpx.imageio/libdpx/EndianSwap.h

@@ -36,10 +36,32 @@
 #ifndef _DPX_ENDIANSWAP_H
 #define _DPX_ENDIANSWAP_H 1
 
+#include <OpenImageIO/fmath.h>
+
+#define USE_OIIO_BYTESWAP 1
+
 
 namespace dpx
 {
 
+#if USE_OIIO_BYTESWAP
+
+template<typename T>
+inline T
+SwapBytes(T& value)
+{
+    return value = OIIO::byteswap(value);
+}
+
+template<typename T>
+void
+SwapBuffer(T* buf, unsigned int len)
+{
+    OIIO::byteswap_span(OIIO::span<T>(buf, len));
+}
+
+#else
+
 template <typename T>
 T SwapBytes(T& value)
 {
@@ -92,6 +114,8 @@ void SwapBuffer(T *buf, unsigned int len)
 		SwapBytes(buf[i]);
 }
 
+#endif
+
 
 template <DataSize SIZE>
 void EndianSwapImageBuffer(void *data, int length)