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Subject[PATCH v2 1/2] xxHash: create arch dependent 32/64-bit xxhash()
Date
xxh32() - fast on both 32/64-bit platforms
xxh64() - fast only on 64-bit platform

Create xxhash() which will pickup fastest version
on compile time.

Add type xxhash_t to map correct hash size.

As result depends on cpu word size,
the main proporse of that - in memory hashing.

Signed-off-by: Timofey Titovets <nefelim4ag@gmail.com>
Acked-by: Andi Kleen <ak@linux.intel.com>
Cc: Linux-kernel <linux-kernel@vger.kernel.org>
---
include/linux/xxhash.h | 24 ++++++++++++++++++++++++
lib/xxhash.c | 10 ++++++++++
2 files changed, 34 insertions(+)

diff --git a/include/linux/xxhash.h b/include/linux/xxhash.h
index 9e1f42cb57e9..195a0ae10e9b 100644
--- a/include/linux/xxhash.h
+++ b/include/linux/xxhash.h
@@ -76,6 +76,7 @@
#define XXHASH_H

#include <linux/types.h>
+#include <linux/bitops.h> /* BITS_PER_LONG */

/*-****************************
* Simple Hash Functions
@@ -107,6 +108,29 @@ uint32_t xxh32(const void *input, size_t length, uint32_t seed);
*/
uint64_t xxh64(const void *input, size_t length, uint64_t seed);

+#if BITS_PER_LONG == 64
+typedef u64 xxhash_t;
+#else
+typedef u32 xxhash_t;
+#endif
+
+/**
+ * xxhash() - calculate 32/64-bit hash based on cpu word size
+ *
+ * @input: The data to hash.
+ * @length: The length of the data to hash.
+ * @seed: The seed can be used to alter the result predictably.
+ *
+ * This function always work as xxh32() for 32-bit systems
+ * and as xxh64() for 64-bit systems.
+ * Because result depends on cpu work size,
+ * the main proporse of that function is for in memory hashing.
+ *
+ * Return: 32/64-bit hash of the data.
+ */
+
+xxhash_t xxhash(const void *input, size_t length, uint64_t seed);
+
/*-****************************
* Streaming Hash Functions
*****************************/
diff --git a/lib/xxhash.c b/lib/xxhash.c
index aa61e2a3802f..7dd1105fcc30 100644
--- a/lib/xxhash.c
+++ b/lib/xxhash.c
@@ -236,6 +236,16 @@ uint64_t xxh64(const void *input, const size_t len, const uint64_t seed)
}
EXPORT_SYMBOL(xxh64);

+xxhash_t xxhash(const void *input, size_t length, uint64_t seed)
+{
+#if BITS_PER_LONG == 64
+ return xxh64(input, length, seed);
+#else
+ return xxh32(input, length, seed);
+#endif
+}
+EXPORT_SYMBOL(xxhash);
+
/*-**************************************************
* Advanced Hash Functions
***************************************************/
--
2.14.1
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