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ARM: 8187/1: add CONFIG_HAVE_ARCH_BITREVERSE to support rbit instruction

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this change add CONFIG_HAVE_ARCH_BITREVERSE config option,
so that we can use some architecture's bitrev hardware instruction
to do bitrev operation.

Introduce __constant_bitrev* macro for constant bitrev operation.

Change __bitrev16() __bitrev32() to be inline function,
don't need export symbol for these tiny functions.

Signed-off-by: Yalin Wang <yalin.wang@sonymobile.com>
Acked-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
This commit is contained in:
Yalin Wang 2014-11-03 03:01:03 +01:00 committed by Russell King
parent 97bf6af1f9
commit 556d2f055b
3 changed files with 84 additions and 19 deletions
repo.diff.show_diff_stats Download patch file Download diff file Expand all files Collapse all files

77
include/linux/bitrev.h
View file

@ -3,14 +3,83 @@
#include <linux/types.h>
extern u8 const byte_rev_table[256];
#ifdef CONFIG_HAVE_ARCH_BITREVERSE
#include <asm/bitrev.h>
static inline u8 bitrev8(u8 byte)
#define __bitrev32 __arch_bitrev32
#define __bitrev16 __arch_bitrev16
#define __bitrev8 __arch_bitrev8
#else
extern u8 const byte_rev_table[256];
static inline u8 __bitrev8(u8 byte)
{
return byte_rev_table[byte];
}
extern u16 bitrev16(u16 in);
extern u32 bitrev32(u32 in);
static inline u16 __bitrev16(u16 x)
{
return (__bitrev8(x & 0xff) << 8) | __bitrev8(x >> 8);
}
static inline u32 __bitrev32(u32 x)
{
return (__bitrev16(x & 0xffff) << 16) | __bitrev16(x >> 16);
}
#endif /* CONFIG_HAVE_ARCH_BITREVERSE */
#define __constant_bitrev32(x) \
({ \
u32 __x = x; \
__x = (__x >> 16) | (__x << 16); \
__x = ((__x & (u32)0xFF00FF00UL) >> 8) | ((__x & (u32)0x00FF00FFUL) << 8); \
__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_bitrev16(x) \
({ \
u16 __x = x; \
__x = (__x >> 8) | (__x << 8); \
__x = ((__x & (u16)0xF0F0U) >> 4) | ((__x & (u16)0x0F0FU) << 4); \
__x = ((__x & (u16)0xCCCCU) >> 2) | ((__x & (u16)0x3333U) << 2); \
__x = ((__x & (u16)0xAAAAU) >> 1) | ((__x & (u16)0x5555U) << 1); \
__x; \
})
#define __constant_bitrev8(x) \
({ \
u8 __x = x; \
__x = (__x >> 4) | (__x << 4); \
__x = ((__x & (u8)0xCCU) >> 2) | ((__x & (u8)0x33U) << 2); \
__x = ((__x & (u8)0xAAU) >> 1) | ((__x & (u8)0x55U) << 1); \
__x; \
})
#define bitrev32(x) \
({ \
u32 __x = x; \
__builtin_constant_p(__x) ? \
__constant_bitrev32(__x) : \
__bitrev32(__x); \
})
#define bitrev16(x) \
({ \
u16 __x = x; \
__builtin_constant_p(__x) ? \
__constant_bitrev16(__x) : \
__bitrev16(__x); \
})
#define bitrev8(x) \
({ \
u8 __x = x; \
__builtin_constant_p(__x) ? \
__constant_bitrev8(__x) : \
__bitrev8(__x) ; \
})
#endif /* _LINUX_BITREV_H */

9
lib/Kconfig
View file

@ -13,6 +13,15 @@ config RAID6_PQ
config BITREVERSE
tristate
config HAVE_ARCH_BITREVERSE
boolean
default n
depends on BITREVERSE
help
This option provides an config for the architecture which have instruction
can do bitreverse operation, we use the hardware instruction if the architecture
have this capability.
config RATIONAL
boolean

17
lib/bitrev.c
View file

@ -1,3 +1,4 @@
#ifndef CONFIG_HAVE_ARCH_BITREVERSE
#include <linux/types.h>
#include <linux/module.h>
#include <linux/bitrev.h>
@ -42,18 +43,4 @@ const u8 byte_rev_table[256] = {
};
EXPORT_SYMBOL_GPL(byte_rev_table);
u16 bitrev16(u16 x)
{
return (bitrev8(x & 0xff) << 8) | bitrev8(x >> 8);
}
EXPORT_SYMBOL(bitrev16);
/**
* bitrev32 - reverse the order of bits in a u32 value
* @x: value to be bit-reversed
*/
u32 bitrev32(u32 x)
{
return (bitrev16(x & 0xffff) << 16) | bitrev16(x >> 16);
}
EXPORT_SYMBOL(bitrev32);
#endif /* CONFIG_HAVE_ARCH_BITREVERSE */