xxhash.h File Reference

#include <stddef.h>

Go to the source code of this file.

Data Structures
struct	XXH32_canonical_t
	Canonical (big endian) representation of XXH32_hash_t. More...
struct	XXH64_canonical_t
	Canonical (big endian) representation of XXH64_hash_t. More...

Macros
#define	XXH_PUBLIC_API   /* do nothing */
#define	XXH_VERSION_MAJOR   0
#define	XXH_VERSION_MINOR   6
#define	XXH_VERSION_RELEASE   5
#define	XXH_VERSION_NUMBER   (XXH_VERSION_MAJOR *100*100 + XXH_VERSION_MINOR *100 + XXH_VERSION_RELEASE)

Typedefs
typedef unsigned int	XXH32_hash_t
typedef struct XXH32_state_s	XXH32_state_t
	The opaque state struct for the XXH32 streaming API.
typedef struct XXH64_state_s	XXH64_state_t
	The opaque state struct for the XXH64 streaming API.
typedef unsigned long long	XXH64_hash_t

Enumerations
enum	XXH_errorcode { XXH_OK =0 , XXH_ERROR }

Functions
XXH_PUBLIC_API unsigned	XXH_versionNumber (void)
XXH_PUBLIC_API XXH32_hash_t	XXH32 (const void *input, size_t length, unsigned int seed)
	Calculates the 32-bit hash of input using xxHash32.
XXH_PUBLIC_API XXH32_state_t *	XXH32_createState (void)
XXH_PUBLIC_API XXH_errorcode	XXH32_freeState (XXH32_state_t *statePtr)
	Frees an XXH32_state_t.
XXH_PUBLIC_API void	XXH32_copyState (XXH32_state_t *dst_state, const XXH32_state_t *src_state)
	Copies one XXH32_state_t to another.
XXH_PUBLIC_API XXH_errorcode	XXH32_reset (XXH32_state_t *statePtr, unsigned int seed)
	Resets an XXH32_state_t to begin a new hash.
XXH_PUBLIC_API XXH_errorcode	XXH32_update (XXH32_state_t *statePtr, const void *input, size_t length)
	Consumes a block of input to an XXH32_state_t.
XXH_PUBLIC_API XXH32_hash_t	XXH32_digest (const XXH32_state_t *statePtr)
	Returns the calculated hash value from an XXH32_state_t.
XXH_PUBLIC_API void	XXH32_canonicalFromHash (XXH32_canonical_t *dst, XXH32_hash_t hash)
	Converts an XXH32_hash_t to a big endian XXH32_canonical_t.
XXH_PUBLIC_API XXH32_hash_t	XXH32_hashFromCanonical (const XXH32_canonical_t *src)
	Converts an XXH32_canonical_t to a native XXH32_hash_t.
XXH_PUBLIC_API XXH64_hash_t	XXH64 (const void *input, size_t length, unsigned long long seed)
	Calculates the 64-bit hash of input using xxHash64.
XXH_PUBLIC_API XXH64_state_t *	XXH64_createState (void)
XXH_PUBLIC_API XXH_errorcode	XXH64_freeState (XXH64_state_t *statePtr)
XXH_PUBLIC_API void	XXH64_copyState (XXH64_state_t *dst_state, const XXH64_state_t *src_state)
XXH_PUBLIC_API XXH_errorcode	XXH64_reset (XXH64_state_t *statePtr, unsigned long long seed)
XXH_PUBLIC_API XXH_errorcode	XXH64_update (XXH64_state_t *statePtr, const void *input, size_t length)
XXH_PUBLIC_API XXH64_hash_t	XXH64_digest (const XXH64_state_t *statePtr)
XXH_PUBLIC_API void	XXH64_canonicalFromHash (XXH64_canonical_t *dst, XXH64_hash_t hash)
XXH_PUBLIC_API XXH64_hash_t	XXH64_hashFromCanonical (const XXH64_canonical_t *src)

Macro Definition Documentation

XXH_PUBLIC_API

#define XXH_PUBLIC_API   /* do nothing */

XXH_INLINE_ALL (and XXH_PRIVATE_API) This is useful to include xxhash functions in static mode in order to inline them, and remove their symbol from the public list. Inlining can offer dramatic performance improvement on small keys. Methodology : #define XXH_INLINE_ALL #include "xxhash.h" xxhash.c is automatically included. It's not useful to compile and link it as a separate module.

XXH_VERSION_MAJOR

#define XXH_VERSION_MAJOR   0

XXH_NAMESPACE, aka Namespace Emulation :

If you want to include and expose xxHash functions from within your own library, but also want to avoid symbol collisions with other libraries which may also include xxHash,

you can use XXH_NAMESPACE, to automatically prefix any public symbol from xxhash library with the value of XXH_NAMESPACE (therefore, avoid NULL and numeric values).

Note that no change is required within the calling program as long as it includes xxhash.h : regular symbol name will be automatically translated by this header.

XXH_VERSION_MINOR

#define XXH_VERSION_MINOR   6

XXH_VERSION_NUMBER

#define XXH_VERSION_NUMBER   (XXH_VERSION_MAJOR *100*100 + XXH_VERSION_MINOR *100 + XXH_VERSION_RELEASE)

XXH_VERSION_RELEASE

#define XXH_VERSION_RELEASE   5

Typedef Documentation

XXH32_hash_t

typedef unsigned int XXH32_hash_t

Enumeration Type Documentation

XXH_errorcode

enum XXH_errorcode

Enumerator
XXH_OK
XXH_ERROR

Function Documentation

XXH32()

XXH_PUBLIC_API XXH32_hash_t XXH32	(	const void *	input,
		size_t	length,
		unsigned int	seed )

Calculates the 32-bit hash of input using xxHash32.

XXH32() : Calculate the 32-bit hash of sequence "length" bytes stored at memory address "input". The memory between input & input+length must be valid (allocated and read-accessible). "seed" can be used to alter the result predictably. Speed on Core 2 Duo @ 3 GHz (single thread, SMHasher benchmark) : 5.4 GB/s

Speed on Core 2 Duo @ 3 GHz (single thread, SMHasher benchmark): 5.4 GB/s

Parameters

input	The block of data to be hashed, at least length bytes in size.
length	The length of input, in bytes.
seed	The 32-bit seed to alter the hash's output predictably.

Precondition

The memory between input and input + length must be valid, readable, contiguous memory. However, if length is 0, input may be NULL. In C++, this also must be TriviallyCopyable.

Returns

The calculated 32-bit hash value.

See also

XXH64(), XXH3_64bits_withSeed(), XXH3_128bits_withSeed(), XXH128(): Direct equivalents for the other variants of xxHash.

XXH32_createState(), XXH32_update(), XXH32_digest(): Streaming version.

XXH32_canonicalFromHash()

XXH_PUBLIC_API void XXH32_canonicalFromHash	(	XXH32_canonical_t *	dst,
		XXH32_hash_t	hash )

Converts an XXH32_hash_t to a big endian XXH32_canonical_t.

Default XXH result types are basic unsigned 32 and 64 bits. The canonical representation follows human-readable write convention, aka big-endian (large digits first). These functions allow transformation of hash result into and from its canonical format. This way, hash values can be written into a file or buffer, remaining comparable across different systems.

Parameters

dst	The XXH32_canonical_t pointer to be stored to.
hash	The XXH32_hash_t to be converted.

Precondition

dst must not be NULL.

Default XXH result types are basic unsigned 32 and 64 bits. The canonical representation follows human-readable write convention, aka big-endian (large digits first). These functions allow transformation of hash result into and from its canonical format. This way, hash values can be written into a file or buffer, remaining comparable across different systems.

XXH32_copyState()

XXH_PUBLIC_API void XXH32_copyState	(	XXH32_state_t *	dst_state,
		const XXH32_state_t *	src_state )

Copies one XXH32_state_t to another.

Parameters

dst_state	The state to copy to.
src_state	The state to copy from.

Precondition

dst_state and src_state must not be NULL and must not overlap.

XXH32_createState()

XXH_PUBLIC_API XXH32_state_t * XXH32_createState

(

void

)

XXH32_digest()

XXH_PUBLIC_API XXH32_hash_t XXH32_digest

(

const XXH32_state_t *

statePtr

)

Returns the calculated hash value from an XXH32_state_t.

Note

Calling XXH32_digest() will not affect statePtr, so you can update, digest, and update again.

Parameters

statePtr

The state struct to calculate the hash from.

Precondition

statePtr must not be NULL.

Returns

The calculated xxHash32 value from that state.

XXH32_freeState()

XXH_PUBLIC_API XXH_errorcode XXH32_freeState

(

XXH32_state_t *

statePtr

)

Frees an XXH32_state_t.

Must be allocated with XXH32_createState().

Parameters

statePtr

A pointer to an XXH32_state_t allocated with XXH32_createState().

Returns

XXH_OK.

XXH32_hashFromCanonical()

XXH_PUBLIC_API XXH32_hash_t XXH32_hashFromCanonical

(

const XXH32_canonical_t *

src

)

Converts an XXH32_canonical_t to a native XXH32_hash_t.

Parameters

src	The XXH32_canonical_t to convert.

Precondition

src must not be NULL.

Returns

The converted hash.

XXH32_reset()

XXH_PUBLIC_API XXH_errorcode XXH32_reset	(	XXH32_state_t *	statePtr,
		unsigned int	seed )

Resets an XXH32_state_t to begin a new hash.

This function resets and seeds a state. Call it before XXH32_update().

Parameters

statePtr	The state struct to reset.
seed	The 32-bit seed to alter the hash result predictably.

Precondition

statePtr must not be NULL.

Returns

XXH_OK on success, XXH_ERROR on failure.

XXH32_update()

XXH_PUBLIC_API XXH_errorcode XXH32_update	(	XXH32_state_t *	statePtr,
		const void *	input,
		size_t	length )

Consumes a block of input to an XXH32_state_t.

Call this to incrementally consume blocks of data.

Parameters

statePtr	The state struct to update.
input	The block of data to be hashed, at least length bytes in size.
length	The length of input, in bytes.

Precondition

statePtr must not be NULL.

The memory between input and input + length must be valid, readable, contiguous memory. However, if length is 0, input may be NULL. In C++, this also must be TriviallyCopyable.

Returns

XXH_OK on success, XXH_ERROR on failure.

XXH64()

XXH_PUBLIC_API XXH64_hash_t XXH64	(	const void *	input,
		size_t	length,
		unsigned long long	seed )

Calculates the 64-bit hash of input using xxHash64.

XXH64() : Calculate the 64-bit hash of sequence of length "len" stored at memory address "input". "seed" can be used to alter the result predictably. This function runs faster on 64-bit systems, but slower on 32-bit systems (see benchmark).

This function usually runs faster on 64-bit systems, but slower on 32-bit systems (see benchmark).

Parameters

input	The block of data to be hashed, at least length bytes in size.
length	The length of input, in bytes.
seed	The 64-bit seed to alter the hash's output predictably.

Precondition

The memory between input and input + length must be valid, readable, contiguous memory. However, if length is 0, input may be NULL. In C++, this also must be TriviallyCopyable.

Returns

The calculated 64-bit hash.

See also

XXH32(), XXH3_64bits_withSeed(), XXH3_128bits_withSeed(), XXH128(): Direct equivalents for the other variants of xxHash.

XXH64_createState(), XXH64_update(), XXH64_digest(): Streaming version.

XXH64_canonicalFromHash()

XXH_PUBLIC_API void XXH64_canonicalFromHash	(	XXH64_canonical_t *	dst,
		XXH64_hash_t	hash )

XXH64_copyState()

XXH_PUBLIC_API void XXH64_copyState	(	XXH64_state_t *	dst_state,
		const XXH64_state_t *	src_state )

XXH64_createState()

XXH_PUBLIC_API XXH64_state_t * XXH64_createState

(

void

)

XXH64_digest()

XXH_PUBLIC_API XXH64_hash_t XXH64_digest

(

const XXH64_state_t *

statePtr

)

XXH64_freeState()

XXH_PUBLIC_API XXH_errorcode XXH64_freeState

(

XXH64_state_t *

statePtr

)

XXH64_hashFromCanonical()

XXH_PUBLIC_API XXH64_hash_t XXH64_hashFromCanonical

(

const XXH64_canonical_t *

src

)

XXH64_reset()

XXH_PUBLIC_API XXH_errorcode XXH64_reset	(	XXH64_state_t *	statePtr,
		unsigned long long	seed )

XXH64_update()

XXH_PUBLIC_API XXH_errorcode XXH64_update	(	XXH64_state_t *	statePtr,
		const void *	input,
		size_t	length )

XXH_versionNumber()

XXH_PUBLIC_API unsigned XXH_versionNumber

(

void

)