fix icc header for big endian architectures

Test: ctest

Author: ram-mohan

lib/include/ultrahdr/icc.h

@@ -13,24 +13,21 @@
 
 #include <memory>
 
-#ifndef USE_BIG_ENDIAN_IN_ICC
-#define USE_BIG_ENDIAN_IN_ICC true
-#endif
+#include "ultrahdr/jpegr.h"
+#include "ultrahdr/gainmapmath.h"
+#include "ultrahdr/jpegrutils.h"
 
 #undef Endian_SwapBE32
 #undef Endian_SwapBE16
-#if USE_BIG_ENDIAN_IN_ICC
-#define Endian_SwapBE32(n) EndianSwap32(n)
-#define Endian_SwapBE16(n) EndianSwap16(n)
-#else
+
+#if UHDR_HOST_BIG_ENDIAN == true
 #define Endian_SwapBE32(n) (n)
 #define Endian_SwapBE16(n) (n)
+#else
+#define Endian_SwapBE32(n) EndianSwap32(n)
+#define Endian_SwapBE16(n) EndianSwap16(n)
 #endif
 
-#include "ultrahdr/jpegr.h"
-#include "ultrahdr/gainmapmath.h"
-#include "ultrahdr/jpegrutils.h"
-
 namespace ultrahdr {
 
 typedef int32_t Fixed;

lib/include/ultrahdr/jpegrutils.h

@@ -13,6 +13,18 @@
 
 #include "ultrahdr/jpegr.h"
 
+#if (defined(__BYTE_ORDER__) && defined(__ORDER_LITTLE_ENDIAN__) && \
+     __BYTE_ORDER__ == __ORDER_LITTLE_ENDIAN__) ||                  \
+    defined(_WIN32) || defined(_WIN64)
+#define UHDR_HOST_BIG_ENDIAN false
+#elif (defined(__BYTE_ORDER__) && defined(__ORDER_BIG_ENDIAN__) && \
+       __BYTE_ORDER__ == __ORDER_BIG_ENDIAN__) ||                  \
+    defined(__BIG_ENDIAN__)
+#define UHDR_HOST_BIG_ENDIAN true
+#else
+#error "Unable to detect endianness."
+#endif
+
 // TODO (dichenzhang): This is old version metadata, new version can be found in
 // https://drive.google.com/file/d/1yUGmjGytRuBa2vpr9eM5Uu8CVhyyddjp/view?resourcekey=0-HGzFrzPQzu5FNYLRAJXQBA
 // and in gainmapmetadata.h/.cpp

lib/include/ultrahdr/multipictureformat.h

@@ -13,24 +13,25 @@
 
 #include <memory>
 
+#include "ultrahdr/jpegr.h"
+#include "ultrahdr/gainmapmath.h"
+#include "ultrahdr/jpegrutils.h"
+
 #ifndef USE_BIG_ENDIAN_IN_MPF
 #define USE_BIG_ENDIAN_IN_MPF true
 #endif
 
 #undef Endian_SwapBE32
 #undef Endian_SwapBE16
-#if USE_BIG_ENDIAN_IN_MPF
-#define Endian_SwapBE32(n) EndianSwap32(n)
-#define Endian_SwapBE16(n) EndianSwap16(n)
-#else
+
+#if (USE_BIG_ENDIAN_IN_MPF == UHDR_HOST_BIG_ENDIAN)
 #define Endian_SwapBE32(n) (n)
 #define Endian_SwapBE16(n) (n)
+#else
+#define Endian_SwapBE32(n) EndianSwap32(n)
+#define Endian_SwapBE16(n) EndianSwap16(n)
 #endif
 
-#include "ultrahdr/jpegr.h"
-#include "ultrahdr/gainmapmath.h"
-#include "ultrahdr/jpegrutils.h"
-
 namespace ultrahdr {
 
 constexpr size_t kNumPictures = 2;