cutils: add OS-independent endian.h
cutils/endian.h provides the helpers defined in endian(3), either by
pulling in the OS's built-in endian.h (where available) or recreating
them using GCC builtins.
Change-Id: Ic8965f67e1efdc03f884dbe6b7fe0276f840e4fc
Signed-off-by: Greg Hackmann <ghackmann@google.com>
diff --git a/include/cutils/endian.h b/include/cutils/endian.h
new file mode 100644
index 0000000..3d27ce6
--- /dev/null
+++ b/include/cutils/endian.h
@@ -0,0 +1,52 @@
+/*
+ * Copyright (C) 2015 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#ifndef __CUTILS_ENDIAN_H
+#define __CUTILS_ENDIAN_H
+
+#if defined(__linux__) && !defined(TEST_CUTILS_ENDIAN_H)
+#include <endian.h>
+#else
+
+#if !defined(__BYTE_ORDER__)
+/* gcc and clang predefine __BYTE_ORDER__, so this should never happen */
+#error Compiler does not define __BYTE_ORDER__
+#elif __BYTE_ORDER__ == __ORDER_BIG_ENDIAN__
+#define htobe16(x) (x)
+#define htobe32(x) (x)
+#define htobe64(x) (x)
+#define htole16(x) __builtin_bswap16(x)
+#define htole32(x) __builtin_bswap32(x)
+#define htole64(x) __builtin_bswap64(x)
+#else
+#define htobe16(x) __builtin_bswap16(x)
+#define htobe32(x) __builtin_bswap32(x)
+#define htobe64(x) __builtin_bswap64(x)
+#define htole16(x) (x)
+#define htole32(x) (x)
+#define htole64(x) (x)
+#endif /* __BYTE_ORDER__ */
+
+#define be16toh(x) htobe16(x)
+#define le16toh(x) htole16(x)
+#define be32toh(x) htobe32(x)
+#define le32toh(x) htole32(x)
+#define be64toh(x) htobe64(x)
+#define le64toh(x) htole64(x)
+
+#endif /* defined(__linux__) */
+
+#endif /* __CUTILS_ENDIAN_H */