This will be used in btrfs, and maybe in others in the future.
Signed-off-by: Liu Bo <bo.li....@oracle.com>
---
crypto/Kconfig | 7 +
crypto/Makefile | 1 +
crypto/xxhash.c | 383 ++++++++++++++++++++++++++++++++++++++++++++++++
include/crypto/xxhash.h | 209 ++++++++++++++++++++++++++
4 files changed, 600 insertions(+)
create mode 100644 crypto/xxhash.c
create mode 100644 include/crypto/xxhash.h
diff --git a/crypto/Kconfig b/crypto/Kconfig
index ce4012a..2e56de0 100644
--- a/crypto/Kconfig
+++ b/crypto/Kconfig
@@ -622,6 +622,13 @@ config CRYPTO_GHASH_CLMUL_NI_INTEL
GHASH is message digest algorithm for GCM (Galois/Counter Mode).
The implementation is accelerated by CLMUL-NI of Intel.
+config CRYPTO_XXH32
+ tristate "XXHASH digest algorithm"
+ select CRYPTO_HASH
+ help
+ xxHash - Fast Hash Algorithm
+ source repository : http://code.google.com/p/xxhash/
+
comment "Ciphers"
config CRYPTO_AES
diff --git a/crypto/Makefile b/crypto/Makefile
index 38e64231..7c3f363 100644
--- a/crypto/Makefile
+++ b/crypto/Makefile
@@ -97,6 +97,7 @@ obj-$(CONFIG_CRYPTO_GHASH) += ghash-generic.o
obj-$(CONFIG_CRYPTO_USER_API) += af_alg.o
obj-$(CONFIG_CRYPTO_USER_API_HASH) += algif_hash.o
obj-$(CONFIG_CRYPTO_USER_API_SKCIPHER) += algif_skcipher.o
+obj-$(CONFIG_CRYPTO_XXH32) += xxhash.o
#
# generic algorithms and the async_tx api
diff --git a/crypto/xxhash.c b/crypto/xxhash.c
new file mode 100644
index 0000000..b84c7cf
--- /dev/null
+++ b/crypto/xxhash.c
@@ -0,0 +1,383 @@
+/*
+ * xxHash - Fast Hash algorithm
+ * Copyright (C) 2012-2014, Yann Collet.
+ * BSD 2-Clause License (http://www.opensource.org/licenses/bsd-license.php)
+
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are met:
+
+ * Redistributions of source code must retain the above copyright notice,
+ * this list of conditions and the following disclaimer.
+ * Redistributions in binary form must reproduce the above
+ * copyright notice, this list of conditions and the following disclaimer
+ * in the documentation and/or other materials provided with the distribution.
+
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+ * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+ * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+ * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+ * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+ * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+ * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+ * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+ * You can contact the author at :
+ * xxHash source repository : http://code.google.com/p/xxhash/
+ */
+
+#include <crypto/internal/hash.h>
+#include <crypto/xxhash.h>
+#include <linux/string.h>
+#include <linux/mm.h>
+#include <linux/module.h>
+#include <linux/init.h>
+#include <linux/types.h>
+#include <linux/slab.h>
+
+static inline u32 XXH_readLE32_align(const u32 * ptr, XXH_endianess endian,
+ XXH_alignment align)
+{
+ if (align == XXH_unaligned)
+ return endian ==
+ XXH_littleEndian ? A32(ptr) : XXH_swap32(A32(ptr));
+ else
+ return endian == XXH_littleEndian ? *ptr : XXH_swap32(*ptr);
+}
+
+static inline u32 XXH_readLE32(const u32 * ptr, XXH_endianess endian)
+{
+ return XXH_readLE32_align(ptr, endian, XXH_unaligned);
+}
+
+/* Simple Hash Functions */
+static inline u32 XXH32_endian_align(const void *input, int len, u32 seed,
+ XXH_endianess endian,
+ XXH_alignment align)
+{
+ const u8 *p = (const u8 *)input;
+ const u8 *const bEnd = p + len;
+ u32 h32;
+
+#ifdef XXH_ACCEPT_NULL_INPUT_POINTER
+ if (p == NULL) {
+ len = 0;
+ p = (const u8 *)(size_t) 16;
+ }
+#endif
+ if (len >= 16) {
+ const u8 *const limit = bEnd - 16;
+ u32 v1 = seed + PRIME32_1 + PRIME32_2;
+ u32 v2 = seed + PRIME32_2;
+ u32 v3 = seed + 0;
+ u32 v4 = seed - PRIME32_1;
+ u32 tmp;
+
+ do {
+ tmp = XXH_readLE32_align((const u32 *)p, endian,
align);
+ v1 += tmp * PRIME32_2;
+ v1 = XXH_rotl32(v1, 13);
+ v1 *= PRIME32_1;
+ p += 4;
+
+ tmp = XXH_readLE32_align((const u32 *)p, endian,
align);
+ v2 += tmp * PRIME32_2;
+ v2 = XXH_rotl32(v2, 13);
+ v2 *= PRIME32_1;
+ p += 4;
+
+ tmp = XXH_readLE32_align((const u32 *)p, endian,
align);
+ v3 += tmp * PRIME32_2;
+ v3 = XXH_rotl32(v3, 13);
+ v3 *= PRIME32_1;
+ p += 4;
+
+ tmp = XXH_readLE32_align((const u32 *)p, endian,
align);
+ v4 += tmp * PRIME32_2;
+ v4 = XXH_rotl32(v4, 13);
+ v4 *= PRIME32_1;
+ p += 4;
+ } while (p <= limit);
+
+ h32 = XXH_rotl32(v1, 1) + XXH_rotl32(v2, 7) +
+ XXH_rotl32(v3, 12) + XXH_rotl32(v4, 18);
+ } else {
+ h32 = seed + PRIME32_5;
+ }
+
+ h32 += (u32) len;
+
+ while (p <= bEnd - 4) {
+ h32 += XXH_readLE32_align((const u32 *)p, endian, align) *
+ PRIME32_3;
+ h32 = XXH_rotl32(h32, 17) * PRIME32_4;
+ p += 4;
+ }
+
+ while (p < bEnd) {
+ h32 += (*p) * PRIME32_5;
+ h32 = XXH_rotl32(h32, 11) * PRIME32_1;
+ p++;
+ }
+
+ h32 ^= h32 >> 15;
+ h32 *= PRIME32_2;
+ h32 ^= h32 >> 13;
+ h32 *= PRIME32_3;
+ h32 ^= h32 >> 16;
+
+ return h32;
+}
+
+static int XXH32_digest(struct shash_desc *desc, const u8 *data,
+ unsigned int len, u8 *out)
+
+//const void *input, int len, u32 seed)
+
+{
+ u32 seed = 0;
+ u32 dst;
+
+ XXH_endianess endian_detected = (XXH_endianess) XXH_CPU_LITTLE_ENDIAN;
+
+#if !defined(XXH_USE_UNALIGNED_ACCESS)
+ /* Input is aligned, let's leverage the speed advantage */
+ if ((((size_t) data) & 3)) {
+ if ((endian_detected == XXH_littleEndian) ||
+ XXH_FORCE_NATIVE_FORMAT)
+ dst = XXH32_endian_align(data, len, seed,
+ XXH_littleEndian,
+ XXH_aligned);
+ else
+ dst = XXH32_endian_align(data, len, seed,
+ XXH_bigEndian, XXH_aligned);
+ }
+
+#endif
+ if ((endian_detected == XXH_littleEndian) || XXH_FORCE_NATIVE_FORMAT)
+ dst = XXH32_endian_align(data, len, seed, XXH_littleEndian,
+ XXH_unaligned);
+ else
+ dst = XXH32_endian_align(data, len, seed, XXH_bigEndian,
+ XXH_unaligned);
+
+ *(__le32 *)out = cpu_to_le32(dst);
+
+ return 0;
+}
+
+/* Advanced Hash Functions */
+static int XXH32_resetState(void *state_in, u32 seed)
+{
+ struct xxhash_state *state = (struct xxhash_state *)state_in;
+ state->seed = seed;
+ state->v1 = seed + PRIME32_1 + PRIME32_2;
+ state->v2 = seed + PRIME32_2;
+ state->v3 = seed + 0;
+ state->v4 = seed - PRIME32_1;
+ state->total_len = 0;
+ state->memsize = 0;
+ return 0;
+}
+
+static int XXH32_init(struct shash_desc *desc)
+{
+ struct xxhash_state *sctx = shash_desc_ctx(desc);
+ XXH32_resetState(sctx, 0);
+
+ return 0;
+}
+
+static inline int XXH32_update_endian(void *state_in, const void *input,
+ int len, XXH_endianess endian)
+{
+ struct xxhash_state *state = (struct xxhash_state *)state_in;
+ const u8 *p = (const u8 *)input;
+ const u8 *const bEnd = p + len;
+
+#ifdef XXH_ACCEPT_NULL_INPUT_POINTER
+ if (input == NULL)
+ return -EINVAL;
+#endif
+ state->total_len += len;
+
+ if (state->memsize + len < 16) { // fill in tmp buffer
+ memcpy(state->memory + state->memsize, input, len);
+ state->memsize += len;
+ return 0;
+ }
+
+ if (state->memsize) { // some data left from previous update
+ memcpy(state->memory + state->memsize, input, 16 -
state->memsize);
+
+ {
+ const u32 *p32 = (const u32 *)state->memory;
+ state->v1 += XXH_readLE32(p32, endian) * PRIME32_2;
+ state->v1 = XXH_rotl32(state->v1, 13);
+ state->v1 *= PRIME32_1;
+ p32++;
+ state->v2 += XXH_readLE32(p32, endian) * PRIME32_2;
+ state->v2 = XXH_rotl32(state->v2, 13);
+ state->v2 *= PRIME32_1;
+ p32++;
+ state->v3 += XXH_readLE32(p32, endian) * PRIME32_2;
+ state->v3 = XXH_rotl32(state->v3, 13);
+ state->v3 *= PRIME32_1;
+ p32++;
+ state->v4 += XXH_readLE32(p32, endian) * PRIME32_2;
+ state->v4 = XXH_rotl32(state->v4, 13);
+ state->v4 *= PRIME32_1;
+ p32++;
+ }
+
+ p += 16 - state->memsize;
+ state->memsize = 0;
+ }
+ if (p <= bEnd - 16) {
+ const u8 *const limit = bEnd - 16;
+ u32 v1 = state->v1;
+ u32 v2 = state->v2;
+ u32 v3 = state->v3;
+ u32 v4 = state->v4;
+
+ do {
+ v1 += XXH_readLE32((const u32 *)p, endian) * PRIME32_2;
+ v1 = XXH_rotl32(v1, 13);
+ v1 *= PRIME32_1;
+ p += 4;
+
+ v2 += XXH_readLE32((const u32 *)p, endian) * PRIME32_2;
+ v2 = XXH_rotl32(v2, 13);
+ v2 *= PRIME32_1;
+ p += 4;
+
+ v3 += XXH_readLE32((const u32 *)p, endian) * PRIME32_2;
+ v3 = XXH_rotl32(v3, 13);
+ v3 *= PRIME32_1;
+ p += 4;
+
+ v4 += XXH_readLE32((const u32 *)p, endian) * PRIME32_2;
+ v4 = XXH_rotl32(v4, 13);
+ v4 *= PRIME32_1;
+ p += 4;
+ } while (p <= limit);
+
+ state->v1 = v1;
+ state->v2 = v2;
+ state->v3 = v3;
+ state->v4 = v4;
+ }
+
+ if (p < bEnd) {
+ memcpy(state->memory, p, bEnd - p);
+ state->memsize = (int)(bEnd - p);
+ }
+
+ return 0;
+}
+
+static int XXH32_update(struct shash_desc *desc, const u8 *data,
+ unsigned int len)
+{
+ struct xxhash_state *sctx = shash_desc_ctx(desc);
+
+ XXH_endianess endian_detected = (XXH_endianess) XXH_CPU_LITTLE_ENDIAN;
+
+ if ((endian_detected == XXH_littleEndian) || XXH_FORCE_NATIVE_FORMAT)
+ return XXH32_update_endian(sctx, data, len, XXH_littleEndian);
+ else
+ return XXH32_update_endian(sctx, data, len, XXH_bigEndian);
+}
+
+static inline u32 XXH32_intermediateDigest_endian(void *state_in,
+ XXH_endianess endian)
+{
+ struct xxhash_state *state = (struct xxhash_state *)state_in;
+ const u8 *p = (const u8 *)state->memory;
+ u8 * bEnd = (u8 *) state->memory + state->memsize;
+ u32 h32;
+
+ if (state->total_len >= 16) {
+ h32 = XXH_rotl32(state->v1, 1) + XXH_rotl32(state->v2, 7) +
+ XXH_rotl32(state->v3, 12) + XXH_rotl32(state->v4, 18);
+ } else {
+ h32 = state->seed + PRIME32_5;
+ }
+
+ h32 += (u32)state->total_len;
+
+ while (p <= bEnd - 4) {
+ h32 += XXH_readLE32((const u32 *)p, endian) * PRIME32_3;
+ h32 = XXH_rotl32(h32, 17) * PRIME32_4;
+ p += 4;
+ }
+
+ while (p < bEnd) {
+ h32 += (*p) * PRIME32_5;
+ h32 = XXH_rotl32(h32, 11) * PRIME32_1;
+ p++;
+ }
+
+ h32 ^= h32 >> 15;
+ h32 *= PRIME32_2;
+ h32 ^= h32 >> 13;
+ h32 *= PRIME32_3;
+ h32 ^= h32 >> 16;
+
+ return h32;
+}
+
+static u32 XXH32_intermediateDigest(void *state_in)
+{
+ XXH_endianess endian_detected = (XXH_endianess) XXH_CPU_LITTLE_ENDIAN;
+
+ if ((endian_detected == XXH_littleEndian) || XXH_FORCE_NATIVE_FORMAT)
+ return XXH32_intermediateDigest_endian(state_in,
+ XXH_littleEndian);
+ else
+ return XXH32_intermediateDigest_endian(state_in, XXH_bigEndian);
+}
+
+static int XXH32_final(struct shash_desc *desc, u8 *out)
+{
+ struct xxhash_state *sctx = shash_desc_ctx(desc);
+ u32 dst = XXH32_intermediateDigest(sctx);
+
+ *(__le32 *)out = cpu_to_le32(dst);
+
+ return 0;
+}
+
+static struct shash_alg alg = {
+ .digestsize = XXH32_DIGEST_SIZE,
+ .init = XXH32_init,
+ .update = XXH32_update,
+ .final = XXH32_final,
+ .digest = XXH32_digest,
+ .descsize = sizeof(struct xxhash_state),
+ .statesize = sizeof(struct xxhash_state),
+ .base = {
+ .cra_name = "xxh32",
+ .cra_blocksize = XXH32_BLOCK_SIZE,
+ .cra_module = THIS_MODULE,
+ }
+};
+
+static int __init xxh32_mod_init(void)
+{
+ return crypto_register_shash(&alg);
+}
+
+static void __exit xxh32_mod_fini(void)
+{
+ crypto_unregister_shash(&alg);
+}
+
+module_init(xxh32_mod_init);
+module_exit(xxh32_mod_fini);
+
+MODULE_LICENSE("GPL");
+MODULE_DESCRIPTION("XXHASH FAST Hash Algorithm");
+MODULE_ALIAS("xxhash");
diff --git a/include/crypto/xxhash.h b/include/crypto/xxhash.h
new file mode 100644
index 0000000..04e1b90
--- /dev/null
+++ b/include/crypto/xxhash.h
@@ -0,0 +1,209 @@
+/*
+ xxHash - Fast Hash algorithm
+ Header File
+ Copyright (C) 2012-2014, Yann Collet.
+ BSD 2-Clause License (http://www.opensource.org/licenses/bsd-license.php)
+
+ Redistribution and use in source and binary forms, with or without
+ modification, are permitted provided that the following conditions are
+ met:
+
+ * Redistributions of source code must retain the above copyright
+ notice, this list of conditions and the following disclaimer.
+ * Redistributions in binary form must reproduce the above
+ copyright notice, this list of conditions and the following disclaimer
+ in the documentation and/or other materials provided with the
+ distribution.
+
+ THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+ A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+ OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+ SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+ LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+ DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+ THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+ OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+ You can contact the author at :
+ - xxHash source repository : http://code.google.com/p/xxhash/
+*/
+
+/* Notice extracted from xxHash homepage :
+
+xxHash is an extremely fast Hash algorithm, running at RAM speed limits.
+It also successfully passes all tests from the SMHasher suite.
+
+Comparison (single thread, Windows Seven 32 bits, using SMHasher on a Core 2
Duo @3GHz)
+
+Name Speed Q.Score Author
+xxHash 5.4 GB/s 10
+CrapWow 3.2 GB/s 2 Andrew
+MumurHash 3a 2.7 GB/s 10 Austin Appleby
+SpookyHash 2.0 GB/s 10 Bob Jenkins
+SBox 1.4 GB/s 9 Bret Mulvey
+Lookup3 1.2 GB/s 9 Bob Jenkins
+SuperFastHash 1.2 GB/s 1 Paul Hsieh
+CityHash64 1.05 GB/s 10 Pike & Alakuijala
+FNV 0.55 GB/s 5 Fowler, Noll, Vo
+CRC32 0.43 GB/s 9
+MD5-32 0.33 GB/s 10 Ronald L. Rivest
+SHA1-32 0.28 GB/s 10
+
+Q.Score is a measure of quality of the hash function.
+It depends on successfully passing SMHasher test set.
+10 is a perfect score.
+*/
+
+#ifndef _CRPTO_XXHASH_H
+#define _CRPTO_XXHASH_H
+
+#include <linux/types.h>
+
+#define XXH32_DIGEST_SIZE 4
+#define XXH32_BLOCK_SIZE 16
+
+/*
+ * Unaligned memory access is automatically enabled for "common" CPU, such as
x86.
+ * For others CPU, the compiler will be more cautious, and insert extra code
to ensure aligned access is respected.
+ * If you know your target CPU supports unaligned memory access, you want to
force this option manually to improve performance.
+ * You can also enable this parameter if you know your input data will always
be aligned (boundaries of 4, for U32).
+ */
+#if defined(__ARM_FEATURE_UNALIGNED) || defined(__i386) || defined(_M_IX86) ||
defined(__x86_64__) || defined(_M_X64)
+ #define XXH_USE_UNALIGNED_ACCESS 1
+#endif
+
+/*
+ * XXH_ACCEPT_NULL_INPUT_POINTER :
+ * If the input pointer is a null pointer, xxHash default behavior is to
trigger a memory access error, since it is a bad pointer.
+ * When this option is enabled, xxHash output for null input pointers will be
the same as a null-length input.
+ * This option has a very small performance cost (only measurable on small
inputs).
+ * By default, this option is disabled. To enable it, uncomment below define :
+ *
+ * #define XXH_ACCEPT_NULL_INPUT_POINTER 1
+ */
+
+/*
+ * XXH_FORCE_NATIVE_FORMAT :
+ * By default, xxHash library provides endian-independant Hash values, based
on little-endian convention.
+ * Results are therefore identical for little-endian and big-endian CPU.
+ * This comes at a performance cost for big-endian CPU, since some swapping is
required to emulate little-endian format.
+ * Should endian-independance be of no importance for your application, you
may set the #define below to 1.
+ * It will improve speed for Big-endian CPU.
+ * This option has no impact on Little_Endian CPU.
+ */
+#define XXH_FORCE_NATIVE_FORMAT 0
+
+typedef struct _U32_S {
+ u32 v;
+} __attribute__ ((__packed__)) U32_S;
+
+#define A32(x) (((U32_S *)(x))->v)
+
+/* Compiler-specific Functions and Macros */
+#define XXH_rotl32(x,r) ((x << r) | (x >> (32 - r)))
+
+#if GCC_VERSION >= 40300
+ #define XXH_swap32 __builtin_bswap32
+#else
+ static inline u32 XXH_swap32(u32 x)
+ {
+ return ((x << 24) & 0xff000000) |
+ ((x << 8) & 0x00ff0000) |
+ ((x >> 8) & 0x0000ff00) |
+ ((x >> 24) & 0x000000ff);
+ }
+#endif
+
+/* Constants */
+#define PRIME32_1 2654435761U
+#define PRIME32_2 2246822519U
+#define PRIME32_3 3266489917U
+#define PRIME32_4 668265263U
+#define PRIME32_5 374761393U
+
+/* Architecture Macros */
+typedef enum {
+ XXH_bigEndian=0,
+ XXH_littleEndian=1
+} XXH_endianess;
+
+#ifndef XXH_CPU_LITTLE_ENDIAN // It is possible to define
XXH_CPU_LITTLE_ENDIAN externally, for example using a compiler switch
+ static const int one = 1;
+ #define XXH_CPU_LITTLE_ENDIAN (*(char*)(&one))
+#endif
+
+/* Macros */
+
+/* use only *after* variable declarations */
+#define XXH_STATIC_ASSERT(c) { enum { XXH_static_assert = 1/(!!(c)) }; }
+
+/* Memory reads */
+typedef enum {
+ XXH_aligned,
+ XXH_unaligned
+} XXH_alignment;
+
+struct xxhash_state {
+ u64 total_len;
+ u32 seed;
+ u32 v1;
+ u32 v2;
+ u32 v3;
+ u32 v4;
+ int memsize;
+ char memory[16];
+};
+
+//****************************
+// Simple Hash Functions
+//****************************
+
+/*
+XXH32() :
+ Calculate the 32-bits hash of sequence of length "len" stored at memory
address "input".
+ The memory between input & input+len must be valid (allocated and
read-accessible).
+ "seed" can be used to alter the result predictably.
+ This function successfully passes all SMHasher tests.
+ Speed on Core 2 Duo @ 3 GHz (single thread, SMHasher benchmark) : 5.4 GB/s
+ Note that "len" is type "int", which means it is limited to 2^31-1.
+ If your data is larger, use the advanced functions below.
+
+unsigned int XXH32 (const void* input, int len, unsigned int seed);
+*/
+
+
+
+//****************************
+// Advanced Hash Functions
+//****************************
+
+/*
+These functions calculate the xxhash of an input provided in several small
packets,
+as opposed to an input provided as a single block.
+
+It must be started with :
+void* XXH32_init()
+The function returns a pointer which holds the state of calculation.
+
+This pointer must be provided as "void* state" parameter for XXH32_update().
+XXH32_update() can be called as many times as necessary.
+The user must provide a valid (allocated) input.
+The function returns an error code, with 0 meaning OK, and any other value
meaning there is an error.
+Note that "len" is type "int", which means it is limited to 2^31-1.
+If your data is larger, it is recommended to chunk your data into blocks
+of size for example 2^30 (1GB) to avoid any "int" overflow issue.
+
+Finally, you can end the calculation anytime, by using XXH32_digest().
+This function returns the final 32-bits hash.
+You must provide the same "void* state" parameter created by XXH32_init().
+Memory will be freed by XXH32_digest().
+
+void* XXH32_init (unsigned int seed);
+XXH_errorcode XXH32_update (void* state, const void* input, int len);
+unsigned int XXH32_final (void* state);
+*/
+
+#endif /* _CRYPTO_XXHASH_H */
--
1.8.1.4
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