diff options
| -rw-r--r-- | include/linux/byteorder/swab.h | 108 |
1 files changed, 69 insertions, 39 deletions
diff --git a/include/linux/byteorder/swab.h b/include/linux/byteorder/swab.h index 25f7f32883e..142134ff164 100644 --- a/include/linux/byteorder/swab.h +++ b/include/linux/byteorder/swab.h @@ -10,6 +10,10 @@ * separated swab functions from cpu_to_XX, * to clean up support for bizarre-endian architectures. * + * Trent Piepho <xyzzy@speakeasy.org> 2007114 + * make constant-folding work, provide C versions that + * gcc can optimize better, explain different versions + * * See asm-i386/byteorder.h and suches for examples of how to provide * architecture-dependent optimized versions * @@ -17,40 +21,66 @@ #include <linux/compiler.h> +/* Functions/macros defined, there are a lot: + * + * ___swabXX + * Generic C versions of the swab functions. + * + * ___constant_swabXX + * C versions that gcc can fold into a compile-time constant when + * the argument is a compile-time constant. + * + * __arch__swabXX[sp]? + * Architecture optimized versions of all the swab functions + * (including the s and p versions). These can be defined in + * asm-arch/byteorder.h. Any which are not, are defined here. + * __arch__swabXXs() is defined in terms of __arch__swabXXp(), which + * is defined in terms of __arch__swabXX(), which is in turn defined + * in terms of ___swabXX(x). + * These must be macros. They may be unsafe for arguments with + * side-effects. + * + * __fswabXX + * Inline function versions of the __arch__ macros. These _are_ safe + * if the arguments have side-effects. Note there are no s and p + * versions of these. + * + * __swabXX[sb] + * There are the ones you should actually use. The __swabXX versions + * will be a constant given a constant argument and use the arch + * specific code (if any) for non-constant arguments. The s and p + * versions always use the arch specific code (constant folding + * doesn't apply). They are safe to use with arguments with + * side-effects. + * + * swabXX[sb] + * Nicknames for __swabXX[sb] to use in the kernel. + */ + /* casts are necessary for constants, because we never know how for sure * how U/UL/ULL map to __u16, __u32, __u64. At least not in a portable way. */ -#define ___swab16(x) \ -({ \ - __u16 __x = (x); \ - ((__u16)( \ - (((__u16)(__x) & (__u16)0x00ffU) << 8) | \ - (((__u16)(__x) & (__u16)0xff00U) >> 8) )); \ -}) -#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 ___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) )); \ -}) +static __inline__ __attribute_const__ __u16 ___swab16(__u16 x) +{ + return x<<8 | x>>8; +} +static __inline__ __attribute_const__ __u32 ___swab32(__u32 x) +{ + return x<<24 | x>>24 | + (x & (__u32)0x0000ff00UL)<<8 | + (x & (__u32)0x00ff0000UL)>>8; +} +static __inline__ __attribute_const__ __u64 ___swab64(__u64 x) +{ + return x<<56 | x>>56 | + (x & (__u64)0x000000000000ff00ULL)<<40 | + (x & (__u64)0x0000000000ff0000ULL)<<24 | + (x & (__u64)0x00000000ff000000ULL)<< 8 | + (x & (__u64)0x000000ff00000000ULL)>> 8 | + (x & (__u64)0x0000ff0000000000ULL)>>24 | + (x & (__u64)0x00ff000000000000ULL)>>40; +} #define ___constant_swab16(x) \ ((__u16)( \ @@ -77,13 +107,13 @@ * provide defaults when no architecture-specific optimization is detected */ #ifndef __arch__swab16 -# define __arch__swab16(x) ({ __u16 __tmp = (x) ; ___swab16(__tmp); }) +# define __arch__swab16(x) ___swab16(x) #endif #ifndef __arch__swab32 -# define __arch__swab32(x) ({ __u32 __tmp = (x) ; ___swab32(__tmp); }) +# define __arch__swab32(x) ___swab32(x) #endif #ifndef __arch__swab64 -# define __arch__swab64(x) ({ __u64 __tmp = (x) ; ___swab64(__tmp); }) +# define __arch__swab64(x) ___swab64(x) #endif #ifndef __arch__swab16p @@ -97,13 +127,13 @@ #endif #ifndef __arch__swab16s -# define __arch__swab16s(x) do { *(x) = __arch__swab16p((x)); } while (0) +# define __arch__swab16s(x) ((void)(*(x) = __arch__swab16p(x))) #endif #ifndef __arch__swab32s -# define __arch__swab32s(x) do { *(x) = __arch__swab32p((x)); } while (0) +# define __arch__swab32s(x) ((void)(*(x) = __arch__swab32p(x))) #endif #ifndef __arch__swab64s -# define __arch__swab64s(x) do { *(x) = __arch__swab64p((x)); } while (0) +# define __arch__swab64s(x) ((void)(*(x) = __arch__swab64p(x))) #endif @@ -113,15 +143,15 @@ #if defined(__GNUC__) && defined(__OPTIMIZE__) # define __swab16(x) \ (__builtin_constant_p((__u16)(x)) ? \ - ___swab16((x)) : \ + ___constant_swab16((x)) : \ __fswab16((x))) # define __swab32(x) \ (__builtin_constant_p((__u32)(x)) ? \ - ___swab32((x)) : \ + ___constant_swab32((x)) : \ __fswab32((x))) # define __swab64(x) \ (__builtin_constant_p((__u64)(x)) ? \ - ___swab64((x)) : \ + ___constant_swab64((x)) : \ __fswab64((x))) #else # define __swab16(x) __fswab16(x) |