*
* Macros and inline functions for endianness conversion.
*
+ * Author: Eric Biggers
+ * Year: 2014, 2015
+ *
* The author dedicates this file to the public domain.
* You can do whatever you want with this file.
*/
/* Watch out for conflict with ntfs-3g/endians.h ... */
#ifndef _NTFS_ENDIANS_H
-static inline u16 bswap16(u16 n)
+#define bswap16_const(n) \
+ ((((u16)(n) & 0x00FF) << 8) | \
+ (((u16)(n) & 0xFF00) >> 8))
+
+#define bswap32_const(n) \
+ ((((u32)(n) & 0x000000FF) << 24) | \
+ (((u32)(n) & 0x0000FF00) << 8) | \
+ (((u32)(n) & 0x00FF0000) >> 8) | \
+ (((u32)(n) & 0xFF000000) >> 24))
+
+#define bswap64_const(n) \
+ ((((u64)(n) & 0x00000000000000FF) << 56) | \
+ (((u64)(n) & 0x000000000000FF00) << 40) | \
+ (((u64)(n) & 0x0000000000FF0000) << 24) | \
+ (((u64)(n) & 0x00000000FF000000) << 8) | \
+ (((u64)(n) & 0x000000FF00000000) >> 8) | \
+ (((u64)(n) & 0x0000FF0000000000) >> 24) | \
+ (((u64)(n) & 0x00FF000000000000) >> 40) | \
+ (((u64)(n) & 0xFF00000000000000) >> 56))
+
+static inline u16 do_bswap16(u16 n)
{
#ifdef compiler_bswap16
return compiler_bswap16(n);
#else
- return (n << 8) | (n >> 8);
+ return bswap16_const(n);
#endif
}
-static inline u32 bswap32(u32 n)
+static inline u32 do_bswap32(u32 n)
{
#ifdef compiler_bswap32
return compiler_bswap32(n);
#else
- return (n << 24) |
- ((n & 0xFF00) << 8) |
- ((n & 0xFF0000) >> 8) |
- (n >> 24);
+ return bswap32_const(n);
#endif
}
-static inline u64 bswap64(u64 n)
+static inline u64 do_bswap64(u64 n)
{
#ifdef compiler_bswap64
return compiler_bswap64(n);
#else
- return (n << 56) |
- ((n & 0xFF00) << 40) |
- ((n & 0xFF0000) << 24) |
- ((n & 0xFF000000) << 8) |
- ((n & 0xFF00000000) >> 8) |
- ((n & 0xFF0000000000) >> 24) |
- ((n & 0xFF000000000000) >> 40) |
- (n >> 56);
+ return bswap64_const(n);
#endif
}
+#define bswap16(n) (__builtin_constant_p(n) ? bswap16_const(n) : do_bswap16(n))
+#define bswap32(n) (__builtin_constant_p(n) ? bswap32_const(n) : do_bswap32(n))
+#define bswap64(n) (__builtin_constant_p(n) ? bswap64_const(n) : do_bswap64(n))
+
#if CPU_IS_BIG_ENDIAN
# define cpu_to_le16(n) ((_force_attr le16)bswap16(n))
# define cpu_to_le32(n) ((_force_attr le32)bswap32(n))