reiserfsprogs: add helpers for constant endian routines

Initializing structures with little endian values requires a const
value. This means that the endian routines that are macro blocks
cause build failures.

This patch introduces constant_ macros that don't involve an
assignment. These can only be used with constant values or
unexpected results may occur.

Signed-off-by: Jeff Mahoney <jeffm@suse.com>

include/swab.h

@@ -9,36 +9,43 @@
 #include <endian.h>
 #include <linux/types.h>
 
-#define __swab16(x) \
-({ \
-        __u16 __x = (x); \
-        ((__u16)( \
-                (((__u16)(__x) & (__u16)0x00ffU) << 8) | \
-                (((__u16)(__x) & (__u16)0xff00U) >> 8) )); \
+#define __constant_swab16(x) ((__u16)(				\
+	(((__u16)(x) & (__u16)0x00ffU) << 8) |			\
+	(((__u16)(x) & (__u16)0xff00U) >> 8) ))
+
+#define __swab16(x)						\
+({								\
+	__u16 __x = (x);					\
+	__constant_swab16(__x);					\
 })
 
-#define __swab32(x) \
-({ \
-        __u32 __x = (x); \
-        ((__u32)( \
-                (((__u32)(__x) & (__u32)0x000000ffUL) << 24) | \
-                (((__u32)(__x) & (__u32)0x0000ff00UL) <<  8) | \
-                (((__u32)(__x) & (__u32)0x00ff0000UL) >>  8) | \
-                (((__u32)(__x) & (__u32)0xff000000UL) >> 24) )); \
+#define __constant_swab32(x) ((__u32)(				\
+	(((__u32)(x) & (__u32)0x000000ffUL) << 24) |		\
+	(((__u32)(x) & (__u32)0x0000ff00UL) <<  8) |		\
+	(((__u32)(x) & (__u32)0x00ff0000UL) >>  8) |		\
+	(((__u32)(x) & (__u32)0xff000000UL) >> 24)))
+
+#define __swab32(x)						\
+({								\
+	__u32 __x = (x);					\
+	__constant_swab32(__x);					\
 })
 
-#define __swab64(x) \
-({ \
-        __u64 __x = (x); \
-        ((__u64)( \
-                (__u64)(((__u64)(__x) & (__u64)0x00000000000000ffULL) << 56) | \
-                (__u64)(((__u64)(__x) & (__u64)0x000000000000ff00ULL) << 40) | \
-                (__u64)(((__u64)(__x) & (__u64)0x0000000000ff0000ULL) << 24) | \
-                (__u64)(((__u64)(__x) & (__u64)0x00000000ff000000ULL) <<  8) | \
-                (__u64)(((__u64)(__x) & (__u64)0x000000ff00000000ULL) >>  8) | \
-                (__u64)(((__u64)(__x) & (__u64)0x0000ff0000000000ULL) >> 24) | \
-                (__u64)(((__u64)(__x) & (__u64)0x00ff000000000000ULL) >> 40) | \
-                (__u64)(((__u64)(__x) & (__u64)0xff00000000000000ULL) >> 56) )); \
+#define __constant_swab64(x) ((__u64)(				\
+	(((__u64)(x) & (__u64)0x00000000000000ffULL) << 56) |	\
+	(((__u64)(x) & (__u64)0x000000000000ff00ULL) << 40) |	\
+	(((__u64)(x) & (__u64)0x0000000000ff0000ULL) << 24) |	\
+	(((__u64)(x) & (__u64)0x00000000ff000000ULL) <<  8) |	\
+	(((__u64)(x) & (__u64)0x000000ff00000000ULL) >>  8) |	\
+	(((__u64)(x) & (__u64)0x0000ff0000000000ULL) >> 24) |	\
+	(((__u64)(x) & (__u64)0x00ff000000000000ULL) >> 40) |	\
+	(((__u64)(x) & (__u64)0xff00000000000000ULL) >> 56)))
+
+
+#define __swab64(x)						\
+({								\
+	__u64 __x = (x);					\
+	__constant_swab64(__x);					\
 })
 
 #ifndef le32_to_cpu
@@ -56,6 +63,13 @@
 #define cpu_to_le16(x) ((__force __le16)(__u16)(x))
 #define le16_to_cpu(x) ((__force __u16)(__le16)(x))
 
+#define constant_cpu_to_le64(x) ((__force __le64)(__u64)(x))
+#define constant_le64_to_cpu(x) ((__force __u64)(__le64)(x))
+#define constant_cpu_to_le32(x) ((__force __le32)(__u32)(x))
+#define constant_le32_to_cpu(x) ((__force __u32)(__le32)(x))
+#define constant_cpu_to_le16(x) ((__force __le16)(__u16)(x))
+#define constant_le16_to_cpu(x) ((__force __u16)(__le16)(x))
+
 #elif __BYTE_ORDER == __BIG_ENDIAN
 #define cpu_to_le64(x) ((__force __le64)__swab64((x)))
 #define le64_to_cpu(x) __swab64((__force __u64)(__le64)(x))
@@ -64,6 +78,13 @@
 #define cpu_to_le16(x) ((__force __le16)__swab16((x)))
 #define le16_to_cpu(x) __swab16((__force __u16)(__le16)(x))
 
+#define constant_cpu_to_le64(x) ((__force __le64)__constant_swab64((x)))
+#define constant_le64_to_cpu(x) __constant_swab64((__force __u64)(__le64)(x))
+#define constant_cpu_to_le32(x) ((__force __le32)__constant_swab32((x)))
+#define constant_le32_to_cpu(x) __constant_swab32((__force __u32)(__le32)(x))
+#define constant_cpu_to_le16(x) ((__force __le16)__constant_swab16((x)))
+#define constant_le16_to_cpu(x) __constant_swab16((__force __u16)(__le16)(x))
+
 #else
 # error "nuxi/pdp-endian archs are not supported"
 #endif