diff options
| author | George Spelvin <linux@sciencehorizons.net> | 2016-05-26 22:11:51 -0400 |
|---|---|---|
| committer | George Spelvin <linux@sciencehorizons.net> | 2016-05-28 15:48:31 -0400 |
| commit | 468a9428521e7d00fb21250af363eb94dc1d6861 (patch) | |
| tree | 75a5e7b73594e643a1f8ca870bcc4fe679bfb610 /include | |
| parent | 2a18da7a9c7886f1c7307f8d3f23f24318583f03 (diff) | |
<linux/hash.h>: Add support for architecture-specific functions
This is just the infrastructure; there are no users yet.
This is modelled on CONFIG_ARCH_RANDOM; a CONFIG_ symbol declares
the existence of <asm/hash.h>.
That file may define its own versions of various functions, and define
HAVE_* symbols (no CONFIG_ prefix!) to suppress the generic ones.
Included is a self-test (in lib/test_hash.c) that verifies the basics.
It is NOT in general required that the arch-specific functions compute
the same thing as the generic, but if a HAVE_* symbol is defined with
the value 1, then equality is tested.
Signed-off-by: George Spelvin <linux@sciencehorizons.net>
Cc: Geert Uytterhoeven <geert@linux-m68k.org>
Cc: Greg Ungerer <gerg@linux-m68k.org>
Cc: Andreas Schwab <schwab@linux-m68k.org>
Cc: Philippe De Muyter <phdm@macq.eu>
Cc: linux-m68k@lists.linux-m68k.org
Cc: Alistair Francis <alistai@xilinx.com>
Cc: Michal Simek <michal.simek@xilinx.com>
Cc: Yoshinori Sato <ysato@users.sourceforge.jp>
Cc: uclinux-h8-devel@lists.sourceforge.jp
Diffstat (limited to 'include')
| -rw-r--r-- | include/linux/hash.h | 27 |
1 files changed, 24 insertions, 3 deletions
diff --git a/include/linux/hash.h b/include/linux/hash.h index 613cfde3a1e0..ad6fa21d977b 100644 --- a/include/linux/hash.h +++ b/include/linux/hash.h @@ -41,19 +41,40 @@ #define GOLDEN_RATIO_32 0x61C88647 #define GOLDEN_RATIO_64 0x61C8864680B583EBull +#ifdef CONFIG_HAVE_ARCH_HASH +/* This header may use the GOLDEN_RATIO_xx constants */ +#include <asm/hash.h> +#endif -static inline u32 __hash_32(u32 val) +/* + * The _generic versions exist only so lib/test_hash.c can compare + * the arch-optimized versions with the generic. + * + * Note that if you change these, any <asm/hash.h> that aren't updated + * to match need to have their HAVE_ARCH_* define values updated so the + * self-test will not false-positive. + */ +#ifndef HAVE_ARCH__HASH_32 +#define __hash_32 __hash_32_generic +#endif +static inline u32 __hash_32_generic(u32 val) { return val * GOLDEN_RATIO_32; } -static inline u32 hash_32(u32 val, unsigned int bits) +#ifndef HAVE_ARCH_HASH_32 +#define hash_32 hash_32_generic +#endif +static inline u32 hash_32_generic(u32 val, unsigned int bits) { /* High bits are more random, so use them. */ return __hash_32(val) >> (32 - bits); } -static __always_inline u32 hash_64(u64 val, unsigned int bits) +#ifndef HAVE_ARCH_HASH_64 +#define hash_64 hash_64_generic +#endif +static __always_inline u32 hash_64_generic(u64 val, unsigned int bits) { #if BITS_PER_LONG == 64 /* 64x64-bit multiply is efficient on all 64-bit processors */ |