xxhash.h File Reference

#include <stddef.h>

Go to the source code of this file.

Classes
struct	XXH32_canonical_t
struct	XXH64_canonical_t

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
typedef unsigned long long	XXH64_hash_t
typedef struct XXH64_state_s	XXH64_state_t

Enumerations
enum	XXH_errorcode { XXH_OK =0 , XXH_ERROR , 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)
XXH_PUBLIC_API XXH32_state_t *	XXH32_createState (void)
XXH_PUBLIC_API XXH_errorcode	XXH32_freeState (XXH32_state_t *statePtr)
XXH_PUBLIC_API void	XXH32_copyState (XXH32_state_t *dst_state, const XXH32_state_t *src_state)
XXH_PUBLIC_API XXH_errorcode	XXH32_reset (XXH32_state_t *statePtr, unsigned int seed)
XXH_PUBLIC_API XXH_errorcode	XXH32_update (XXH32_state_t *statePtr, const void *input, size_t length)
XXH_PUBLIC_API XXH32_hash_t	XXH32_digest (const XXH32_state_t *statePtr)
XXH_PUBLIC_API void	XXH32_canonicalFromHash (XXH32_canonical_t *dst, XXH32_hash_t hash)
XXH_PUBLIC_API XXH32_hash_t	XXH32_hashFromCanonical (const XXH32_canonical_t *src)
XXH_PUBLIC_API XXH64_hash_t	XXH64 (const void *input, size_t length, unsigned long long seed)
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.

Definition at line 110 of file xxhash.h.

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.

Definition at line 152 of file xxhash.h.

XXH_VERSION_MINOR

#define XXH_VERSION_MINOR   6

Definition at line 153 of file xxhash.h.

XXH_VERSION_NUMBER

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

Definition at line 155 of file xxhash.h.

XXH_VERSION_RELEASE

#define XXH_VERSION_RELEASE   5

Definition at line 154 of file xxhash.h.

Typedef Documentation

XXH32_hash_t

typedef unsigned int XXH32_hash_t

Definition at line 162 of file xxhash.h.

XXH32_state_t

typedef struct XXH32_state_s XXH32_state_t

Definition at line 169 of file xxhash.h.

XXH64_hash_t

typedef unsigned long long XXH64_hash_t

Definition at line 219 of file xxhash.h.

XXH64_state_t

typedef struct XXH64_state_s XXH64_state_t

Definition at line 226 of file xxhash.h.

Enumeration Type Documentation

XXH_errorcode

enum XXH_errorcode

Enumerator
XXH_OK
XXH_ERROR
XXH_OK
XXH_ERROR

Definition at line 79 of file xxhash.h.

{ XXH_OK=0, XXH_ERROR } XXH_errorcode;

Function Documentation

XXH32()

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

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

Definition at line 392 of file xxhash.c.

{
#if 0
    /* Simple version, good for code maintenance, but unfortunately slow for small inputs */
    XXH32_state_t state;
    XXH32_reset(&state, seed);
    XXH32_update(&state, input, len);
    return XXH32_digest(&state);
#else
    XXH_endianess endian_detected = (XXH_endianess)XXH_CPU_LITTLE_ENDIAN;
 
    if (XXH_FORCE_ALIGN_CHECK) {
        if ((((size_t)input) & 3) == 0) {   /* Input is 4-bytes aligned, leverage the speed benefit */
            if ((endian_detected==XXH_littleEndian) || XXH_FORCE_NATIVE_FORMAT)
                return XXH32_endian_align(input, len, seed, XXH_littleEndian, XXH_aligned);
            else
                return XXH32_endian_align(input, len, seed, XXH_bigEndian, XXH_aligned);
    }   }
 
    if ((endian_detected==XXH_littleEndian) || XXH_FORCE_NATIVE_FORMAT)
        return XXH32_endian_align(input, len, seed, XXH_littleEndian, XXH_unaligned);
    else
        return XXH32_endian_align(input, len, seed, XXH_bigEndian, XXH_unaligned);
#endif
}

XXH32_canonicalFromHash()

XXH_PUBLIC_API void XXH32_canonicalFromHash	(	XXH32_canonical_t *	dst,
		XXH32_hash_t	hash
	)

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.

Definition at line 565 of file xxhash.c.

{
    XXH_STATIC_ASSERT(sizeof(XXH32_canonical_t) == sizeof(XXH32_hash_t));
    if (XXH_CPU_LITTLE_ENDIAN) hash = XXH_swap32(hash);
    memcpy(dst, &hash, sizeof(*dst));
}

XXH32_copyState()

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

Definition at line 432 of file xxhash.c.

{
    memcpy(dstState, srcState, sizeof(*dstState));
}

XXH32_createState()

XXH_PUBLIC_API XXH32_state_t* XXH32_createState

(

void

)

Definition at line 422 of file xxhash.c.

{
    return (XXH32_state_t*)XXH_malloc(sizeof(XXH32_state_t));
}

XXH32_digest()

XXH_PUBLIC_API XXH32_hash_t XXH32_digest

(

const XXH32_state_t *

statePtr

)

Definition at line 546 of file xxhash.c.

{
    XXH_endianess endian_detected = (XXH_endianess)XXH_CPU_LITTLE_ENDIAN;
 
    if ((endian_detected==XXH_littleEndian) || XXH_FORCE_NATIVE_FORMAT)
        return XXH32_digest_endian(state_in, XXH_littleEndian);
    else
        return XXH32_digest_endian(state_in, XXH_bigEndian);
}

XXH32_freeState()

XXH_PUBLIC_API XXH_errorcode XXH32_freeState

(

XXH32_state_t *

statePtr

)

Definition at line 426 of file xxhash.c.

{
    XXH_free(statePtr);
    return XXH_OK;
}

XXH32_hashFromCanonical()

XXH_PUBLIC_API XXH32_hash_t XXH32_hashFromCanonical

(

const XXH32_canonical_t *

src

)

Definition at line 572 of file xxhash.c.

{
    return XXH_readBE32(src);
}

XXH32_reset()

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

Definition at line 437 of file xxhash.c.

{
    XXH32_state_t state;   /* using a local state to memcpy() in order to avoid strict-aliasing warnings */
    memset(&state, 0, sizeof(state));
    state.v1 = seed + PRIME32_1 + PRIME32_2;
    state.v2 = seed + PRIME32_2;
    state.v3 = seed + 0;
    state.v4 = seed - PRIME32_1;
    /* do not write into reserved, planned to be removed in a future version */
    memcpy(statePtr, &state, sizeof(state) - sizeof(state.reserved));
    return XXH_OK;
}

XXH32_update()

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

Definition at line 515 of file xxhash.c.

{
    XXH_endianess endian_detected = (XXH_endianess)XXH_CPU_LITTLE_ENDIAN;
 
    if ((endian_detected==XXH_littleEndian) || XXH_FORCE_NATIVE_FORMAT)
        return XXH32_update_endian(state_in, input, len, XXH_littleEndian);
    else
        return XXH32_update_endian(state_in, input, len, XXH_bigEndian);
}

XXH64()

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

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).

Definition at line 855 of file xxhash.c.

{
#if 0
    /* Simple version, good for code maintenance, but unfortunately slow for small inputs */
    XXH64_state_t state;
    XXH64_reset(&state, seed);
    XXH64_update(&state, input, len);
    return XXH64_digest(&state);
#else
    XXH_endianess endian_detected = (XXH_endianess)XXH_CPU_LITTLE_ENDIAN;
 
    if (XXH_FORCE_ALIGN_CHECK) {
        if ((((size_t)input) & 7)==0) {  /* Input is aligned, let's leverage the speed advantage */
            if ((endian_detected==XXH_littleEndian) || XXH_FORCE_NATIVE_FORMAT)
                return XXH64_endian_align(input, len, seed, XXH_littleEndian, XXH_aligned);
            else
                return XXH64_endian_align(input, len, seed, XXH_bigEndian, XXH_aligned);
    }   }
 
    if ((endian_detected==XXH_littleEndian) || XXH_FORCE_NATIVE_FORMAT)
        return XXH64_endian_align(input, len, seed, XXH_littleEndian, XXH_unaligned);
    else
        return XXH64_endian_align(input, len, seed, XXH_bigEndian, XXH_unaligned);
#endif
}

XXH64_canonicalFromHash()

XXH_PUBLIC_API void XXH64_canonicalFromHash	(	XXH64_canonical_t *	dst,
		XXH64_hash_t	hash
	)

Definition at line 1018 of file xxhash.c.

{
    XXH_STATIC_ASSERT(sizeof(XXH64_canonical_t) == sizeof(XXH64_hash_t));
    if (XXH_CPU_LITTLE_ENDIAN) hash = XXH_swap64(hash);
    memcpy(dst, &hash, sizeof(*dst));
}

XXH64_copyState()

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

Definition at line 893 of file xxhash.c.

{
    memcpy(dstState, srcState, sizeof(*dstState));
}

XXH64_createState()

XXH_PUBLIC_API XXH64_state_t* XXH64_createState

(

void

)

Definition at line 883 of file xxhash.c.

{
    return (XXH64_state_t*)XXH_malloc(sizeof(XXH64_state_t));
}

XXH64_digest()

XXH_PUBLIC_API XXH64_hash_t XXH64_digest

(

const XXH64_state_t *

statePtr

)

Definition at line 1005 of file xxhash.c.

{
    XXH_endianess endian_detected = (XXH_endianess)XXH_CPU_LITTLE_ENDIAN;
 
    if ((endian_detected==XXH_littleEndian) || XXH_FORCE_NATIVE_FORMAT)
        return XXH64_digest_endian(state_in, XXH_littleEndian);
    else
        return XXH64_digest_endian(state_in, XXH_bigEndian);
}

XXH64_freeState()

XXH_PUBLIC_API XXH_errorcode XXH64_freeState

(

XXH64_state_t *

statePtr

)

Definition at line 887 of file xxhash.c.

{
    XXH_free(statePtr);
    return XXH_OK;
}

XXH64_hashFromCanonical()

XXH_PUBLIC_API XXH64_hash_t XXH64_hashFromCanonical

(

const XXH64_canonical_t *

src

)

Definition at line 1025 of file xxhash.c.

{
    return XXH_readBE64(src);
}

XXH64_reset()

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

Definition at line 898 of file xxhash.c.

{
    XXH64_state_t state;   /* using a local state to memcpy() in order to avoid strict-aliasing warnings */
    memset(&state, 0, sizeof(state));
    state.v1 = seed + PRIME64_1 + PRIME64_2;
    state.v2 = seed + PRIME64_2;
    state.v3 = seed + 0;
    state.v4 = seed - PRIME64_1;
     /* do not write into reserved, planned to be removed in a future version */
    memcpy(statePtr, &state, sizeof(state) - sizeof(state.reserved));
    return XXH_OK;
}

XXH64_update()

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

Definition at line 971 of file xxhash.c.

{
    XXH_endianess endian_detected = (XXH_endianess)XXH_CPU_LITTLE_ENDIAN;
 
    if ((endian_detected==XXH_littleEndian) || XXH_FORCE_NATIVE_FORMAT)
        return XXH64_update_endian(state_in, input, len, XXH_littleEndian);
    else
        return XXH64_update_endian(state_in, input, len, XXH_bigEndian);
}

XXH_versionNumber()

XXH_PUBLIC_API unsigned XXH_versionNumber

(

void

)

Definition at line 257 of file xxhash.c.

{ return XXH_VERSION_NUMBER; }