Use the compiler for endian conversions
clang and gcc both define macros describing the endianess of the target
architecture and have builtin macros for byte swapping. The macros
expand in place and lets the compiler insert specialised assembly if it
so chooses.
Change-Id: I6060a0a7952f0863797db65d471f1d21c215b671
diff --git a/inc/std.h b/inc/std.h
index caed9dd..7c10200 100644
--- a/inc/std.h
+++ b/inc/std.h
@@ -12,41 +12,46 @@
size_t strlen(const char *str);
int strcmp(const char *a, const char *b);
-static inline uint16_t be16toh(uint16_t v)
-{
- return v << 8 | v >> 8;
-}
+#if __BYTE_ORDER__ == __ORDER_LITTLE_ENDIAN__
-static inline uint32_t be32toh(uint32_t v)
-{
- /* TODO: no conversion needed if native is big endian. */
- return (v << 24) |
- (v >> 24) |
- ((v & 0xff00) << 8) |
- ((v & 0xff0000) >> 8);
-}
+#define be16toh(v) __builtin_bswap16(v)
+#define be32toh(v) __builtin_bswap32(v)
+#define be64toh(v) __builtin_bswap64(v)
-static inline uint64_t be64toh(uint64_t v)
-{
- /* TODO: no conversion needed if native is big endian. */
- return (v << 56) |
- (v >> 56) |
- ((v & 0xff00) << 40) |
- ((v & 0xff000000000000) >> 40) |
- ((v & 0xff0000) << 24) |
- ((v & 0xff0000000000) >> 24) |
- ((v & 0xff000000) << 8) |
- ((v & 0xff00000000) >> 8);
-}
+#define htobe16(v) __builtin_bswap16(v)
+#define htobe32(v) __builtin_bswap32(v)
+#define htobe64(v) __builtin_bswap64(v)
-static inline uint32_t htobe32(uint32_t v)
-{
- return be32toh(v);
-}
+#define le16toh(v) (v)
+#define le32toh(v) (v)
+#define le64toh(v) (v)
-static inline uint64_t htobe64(uint64_t v)
-{
- return be64toh(v);
-}
+#define htole16(v) (v)
+#define htole32(v) (v)
+#define htole64(v) (v)
+
+#elif __BYTE_ORDER__ == __ORDER_BIG_ENDIAN__
+
+#define be16toh(v) (v)
+#define be32toh(v) (v)
+#define be64toh(v) (v)
+
+#define htobe16(v) (v)
+#define htobe32(v) (v)
+#define htobe64(v) (v)
+
+#define le16toh(v) __builtin_bswap16(v)
+#define le32toh(v) __builtin_bswap32(v)
+#define le64toh(v) __builtin_bswap64(v)
+
+#define htole16(v) __builtin_bswap16(v)
+#define htole32(v) __builtin_bswap32(v)
+#define htole64(v) __builtin_bswap64(v)
+
+#else /* __BYTE_ORDER__ != __ORDER_LITTLE_ENDIAN__ && __BYTE_ORDER__ != __ORDER_BIG_ENDIAN__ */
+
+#error "Unsupported byte order"
+
+#endif
#endif /* STD_H */
