Add big-endian build option

Author: solidpixel

CMakeLists.txt

@@ -45,6 +45,7 @@ option(ASTCENC_ISA_NONE "Enable astcenc builds for no SIMD")
 option(ASTCENC_ISA_NATIVE "Enable astcenc builds for native SIMD")
 option(ASTCENC_DECOMPRESSOR "Enable astcenc builds for decompression only")
 option(ASTCENC_SHAREDLIB "Enable astcenc builds with core library shared objects")
+option(ASTCENC_BIG_ENDIAN "Enable astcenc big-endian support")
 option(ASTCENC_DIAGNOSTICS "Enable astcenc builds with diagnostic trace")
 option(ASTCENC_ASAN "Enable astcenc builds with address sanitizer")
 option(ASTCENC_UBSAN "Enable astcenc builds with undefined behavior sanitizer")
@@ -137,6 +138,9 @@ if("${CMAKE_SYSTEM_NAME}" STREQUAL "Darwin")
     printopt("Universal bin      " ${ASTCENC_UNIVERSAL_BUILD})
 endif()
 printopt("Invariance         " ${ASTCENC_INVARIANCE})
+if(${ASTCENC_BIG_ENDIAN})
+    printopt("Big endian         " ${ASTCENC_BIG_ENDIAN})
+endif()
 printopt("Shared libs        " ${ASTCENC_SHAREDLIB})
 printopt("Decompressor       " ${ASTCENC_DECOMPRESSOR})
 message(STATUS "Developer options")

Source/UnitTest/cmake_core.cmake

@@ -85,6 +85,12 @@ if(${ASTCENC_ISA_SIMD} MATCHES "none")
             ASTCENC_POPCNT=0
             ASTCENC_F16C=0)
 
+    if(${ASTCENC_BIG_ENDIAN})
+        target_compile_definitions(${ASTCENC_TEST}
+            PRIVATE
+                ASTCENC_BIG_ENDIAN=1)
+    endif()
+
 elseif(${ASTCENC_ISA_SIMD} MATCHES "neon")
     target_compile_definitions(${ASTCENC_TEST}
         PRIVATE

Source/cmake_core.cmake

@@ -284,6 +284,12 @@ macro(astcenc_set_properties ASTCENC_TARGET_NAME ASTCENC_VENEER_TYPE)
                 ASTCENC_POPCNT=0
                 ASTCENC_F16C=0)
 
+        if(${ASTCENC_BIG_ENDIAN})
+            target_compile_definitions(${ASTCENC_TARGET_NAME}
+                PRIVATE
+                    ASTCENC_BIG_ENDIAN=1)
+        endif()
+
     elseif(${ASTCENC_ISA_SIMD} MATCHES "neon")
         target_compile_definitions(${ASTCENC_TARGET_NAME}
             PRIVATE