| Message ID | bc92eb1507448731163ae67fc888668d327f9168.1480551148.git.stillcompiling@gmail.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
On Thu, 1 Dec 2016 09:04:50 -0800 Joshua Clayton stillcompiling@gmail.com wrote: ... >diff --git a/arch/arm/include/asm/bitrev.h b/arch/arm/include/asm/bitrev.h >index ec291c3..6d2e9ca 100644 >--- a/arch/arm/include/asm/bitrev.h >+++ b/arch/arm/include/asm/bitrev.h >@@ -17,4 +17,9 @@ static __always_inline __attribute_const__ u8 __arch_bitrev8(u8 x) > return __arch_bitrev32((u32)x) >> 24; > } > >+static __always_inline __attribute_const__ u32 __arch_bitrev8x4(u32 x) >+{ >+ __asm__ ("rbit %0, %1; rev %0, %0" : "=r" (x) : "r" (x)); return x; >+} otherwise you get In function '__arch_bitrev8x4': warning: no return statement in function returning non-void [-Wreturn-type] -- Anatolij
Hello Anatolij, Thanks for the review. On 12/01/2016 02:45 PM, Anatolij Gustschin wrote: > On Thu, 1 Dec 2016 09:04:50 -0800 > Joshua Clayton stillcompiling@gmail.com wrote: > ... >> diff --git a/arch/arm/include/asm/bitrev.h b/arch/arm/include/asm/bitrev.h >> index ec291c3..6d2e9ca 100644 >> --- a/arch/arm/include/asm/bitrev.h >> +++ b/arch/arm/include/asm/bitrev.h >> @@ -17,4 +17,9 @@ static __always_inline __attribute_const__ u8 __arch_bitrev8(u8 x) >> return __arch_bitrev32((u32)x) >> 24; >> } >> >> +static __always_inline __attribute_const__ u32 __arch_bitrev8x4(u32 x) >> +{ >> + __asm__ ("rbit %0, %1; rev %0, %0" : "=r" (x) : "r" (x)); > return x; Oops thats a little embarrassing; I'll add a return. >> +} > otherwise you get > > In function '__arch_bitrev8x4': > warning: no return statement in function returning non-void [-Wreturn-type] > > -- > Anatolij I wonder why I do not see this warning when compiling. The inlining, maybe? Joshua
Hi Joshua, On Thu, 1 Dec 2016 16:04:09 -0800 Joshua Clayton stillcompiling@gmail.com wrote: ... >>> +static __always_inline __attribute_const__ u32 __arch_bitrev8x4(u32 x) >>> +{ >>> + __asm__ ("rbit %0, %1; rev %0, %0" : "=r" (x) : "r" (x)); >> return x; >Oops thats a little embarrassing; >I'll add a return. >>> +} >> otherwise you get >> >> In function '__arch_bitrev8x4': >> warning: no return statement in function returning non-void [-Wreturn-type] >> > >I wonder why I do not see this warning when compiling. The inlining, maybe? do you have CONFIG_HAVE_ARCH_BITREVERSE=y in your .config? Probably not optimized code is used, otherwise you will send wrong data to FPGA (due to wrong return values from __arch_bitrev8x4). Anatolij
diff --git a/arch/arm/include/asm/bitrev.h b/arch/arm/include/asm/bitrev.h index ec291c3..6d2e9ca 100644 --- a/arch/arm/include/asm/bitrev.h +++ b/arch/arm/include/asm/bitrev.h @@ -17,4 +17,9 @@ static __always_inline __attribute_const__ u8 __arch_bitrev8(u8 x) return __arch_bitrev32((u32)x) >> 24; } +static __always_inline __attribute_const__ u32 __arch_bitrev8x4(u32 x) +{ + __asm__ ("rbit %0, %1; rev %0, %0" : "=r" (x) : "r" (x)); +} + #endif diff --git a/include/linux/bitrev.h b/include/linux/bitrev.h index fb790b8..b1cfa1a 100644 --- a/include/linux/bitrev.h +++ b/include/linux/bitrev.h @@ -9,6 +9,7 @@ #define __bitrev32 __arch_bitrev32 #define __bitrev16 __arch_bitrev16 #define __bitrev8 __arch_bitrev8 +#define __bitrev8x4 __arch_bitrev8x4 #else extern u8 const byte_rev_table[256]; @@ -27,6 +28,14 @@ static inline u32 __bitrev32(u32 x) return (__bitrev16(x & 0xffff) << 16) | __bitrev16(x >> 16); } +static inline u32 __bitrev8x4(u32 x) +{ + return(__bitrev8(x & 0xff) | + (__bitrev8((x >> 8) & 0xff) << 8) | + (__bitrev8((x >> 16) & 0xff) << 16) | + (__bitrev8((x >> 24) & 0xff) << 24)); +} + #endif /* CONFIG_HAVE_ARCH_BITREVERSE */ #define __constant_bitrev32(x) \ @@ -50,6 +59,15 @@ static inline u32 __bitrev32(u32 x) __x; \ }) +#define __constant_bitrev8x4(x) \ +({ \ + u32 __x = x; \ + __x = ((__x & (u32)0xF0F0F0F0UL) >> 4) | ((__x & (u32)0x0F0F0F0FUL) << 4); \ + __x = ((__x & (u32)0xCCCCCCCCUL) >> 2) | ((__x & (u32)0x33333333UL) << 2); \ + __x = ((__x & (u32)0xAAAAAAAAUL) >> 1) | ((__x & (u32)0x55555555UL) << 1); \ + __x; \ +}) + #define __constant_bitrev8(x) \ ({ \ u8 __x = x; \ @@ -75,6 +93,14 @@ static inline u32 __bitrev32(u32 x) __bitrev16(__x); \ }) +#define bitrev8x4(x) \ +({ \ + u32 __x = x; \ + __builtin_constant_p(__x) ? \ + __constant_bitrev8x4(__x) : \ + __bitrev8x4(__x); \ +}) + #define bitrev8(x) \ ({ \ u8 __x = x; \
Add a function to reverse bytes within a 32 bit word. This function is more efficient than using the 8 bit version when iterating over an array Signed-off-by: Joshua Clayton <stillcompiling@gmail.com> --- Looking for an ACK from Russell King on this patch (or at least the arm specific implementation) arch/arm/include/asm/bitrev.h | 5 +++++ include/linux/bitrev.h | 26 ++++++++++++++++++++++++++ 2 files changed, 31 insertions(+)