vl_hash.h File Reference

#include "vl_memory.h"

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Macros
#define	VL_HASH_STRING   vlHashString
#define	VL_HASH_BYTES   vlHashString
#define	VL_HASH_UINT8   vlHash8
#define	VL_HASH_UINT16   vlHash16
#define	VL_HASH_UINT32   vlHash32
#define	VL_HASH_UINT64   vlHash64
#define	VL_HASH_INT8   vlHash8
#define	VL_HASH_INT16   vlHash16
#define	VL_HASH_INT32   vlHash32
#define	VL_HASH_INT64   vlHash64
#define	VL_HASH_FLOAT   vlHashFloat
#define	VL_HASH_DOUBLE   vlHashDouble
#define	vlHashChar   vlHash8
#define	vlHashShort   vlHash16
#define	vlHashInt   vlHash32
#define	vlHashLong   vlHash64
#define	vlHashUChar   vlHash8
#define	vlHashUShort   vlHash16
#define	vlHashUInt   vlHash32
#define	vlHashULong   vlHash64
#define	vlHashCombine(a, b)   (vl_hash)(((a) ^ (b)) + 0b11101111100100101101101011001011 + ((a) << 6) + ((a) >> 2))
	Combine two instances of vl_hash.

Typedefs
typedef vl_ularge_t	vl_hash
	Hash function return type.
typedef vl_hash(*	vl_hash_function) (const void *data, vl_memsize_t dataSize)
	Hash function typedef.

Functions
vl_hash	vlHashString (const void *data, vl_memsize_t dataSize)
	Hashes the specified string.
vl_hash	vlHash8 (const void *data, vl_memsize_t)
	Generates a hash code for the 8-bit sequence at the specified address.
vl_hash	vlHash16 (const void *data, vl_memsize_t)
	Generates a hash code for the 16-bit sequence at the specified address. This is a direct bitcast of an 8-bit sequence to a 64-bit sequence. The returned value will equal the value of the original sequence.
vl_hash	vlHash32 (const void *data, vl_memsize_t)
	Generates a hash code for the 32-bit sequence at the specified address.
vl_hash	vlHash64 (const void *data, vl_memsize_t)
	Generates a hash code for the 64-bit sequence at the specified address.

Macro Definition Documentation

VL_HASH_BYTES

#define VL_HASH_BYTES   vlHashString

VL_HASH_DOUBLE

#define VL_HASH_DOUBLE   vlHashDouble

VL_HASH_FLOAT

#define VL_HASH_FLOAT   vlHashFloat

VL_HASH_INT16

#define VL_HASH_INT16   vlHash16

VL_HASH_INT32

#define VL_HASH_INT32   vlHash32

VL_HASH_INT64

#define VL_HASH_INT64   vlHash64

VL_HASH_INT8

#define VL_HASH_INT8   vlHash8

VL_HASH_STRING

#define VL_HASH_STRING   vlHashString

VL_HASH_UINT16

#define VL_HASH_UINT16   vlHash16

VL_HASH_UINT32

#define VL_HASH_UINT32   vlHash32

VL_HASH_UINT64

#define VL_HASH_UINT64   vlHash64

VL_HASH_UINT8

#define VL_HASH_UINT8   vlHash8

vlHashChar

#define vlHashChar   vlHash8

vlHashCombine

#define vlHashCombine	(		a,
			b )   (vl_hash)(((a) ^ (b)) + 0b11101111100100101101101011001011 + ((a) << 6) + ((a) >> 2))

Combine two instances of vl_hash.

Based on the algorithm in the Boost C++ libraries by the same name. The magic number in this macro is intended to act as random bits, where each is equally likely to be a 1 or 0 with no relationships.

Parameters

a	vl_hash value
b	vl_hash value

Returns

merged hash

vlHashInt

#define vlHashInt   vlHash32

vlHashLong

#define vlHashLong   vlHash64

vlHashShort

#define vlHashShort   vlHash16

vlHashUChar

#define vlHashUChar   vlHash8

vlHashUInt

#define vlHashUInt   vlHash32

vlHashULong

#define vlHashULong   vlHash64

vlHashUShort

#define vlHashUShort   vlHash16

Typedef Documentation

vl_hash

typedef vl_ularge_t vl_hash

Hash function return type.

vl_hash_function

typedef vl_hash(* vl_hash_function) (const void *data, vl_memsize_t dataSize)

Hash function typedef.

This function definition

Parameters

data	read-only pointer to the data that will be hashed
dataSize	length of the data, in bytes. Usually this can be ignored unless the data is variable in length.

Function Documentation

vlHash16()

vl_hash vlHash16	(	const void *	data,
		vl_memsize_t	s )

Generates a hash code for the 16-bit sequence at the specified address. This is a direct bitcast of an 8-bit sequence to a 64-bit sequence. The returned value will equal the value of the original sequence.

Parameters

data

pointer

Returns

hash code

vlHash32()

vl_hash vlHash32	(	const void *	data,
		vl_memsize_t	s )

Generates a hash code for the 32-bit sequence at the specified address.

This is a direct bitcast of an 32-bit sequence to a 64-bit sequence. The returned value will equal the value of the original sequence.

Parameters

data

pointer

Returns

hash code

vlHash64()

vl_hash vlHash64	(	const void *	data,
		vl_memsize_t	s )

Generates a hash code for the 64-bit sequence at the specified address.

The returned value will equal the value of the original sequence.

Parameters

data

pointer

Returns

hash code

vlHash8()

vl_hash vlHash8	(	const void *	data,
		vl_memsize_t	s )

Generates a hash code for the 8-bit sequence at the specified address.

This is a direct bitcast of an 8-bit sequence to a 64-bit sequence. The returned value will equal the value of the original sequence.

Parameters

data

pointer

Returns

hash code

vlHashString()

vl_hash vlHashString	(	const void *	data,
		vl_memsize_t	dataSize )

Hashes the specified string.

Uses the FNV-1A-64 string hashing algorithm. See here: https://en.wikipedia.org/wiki/Fowler%E2%80%93Noll%E2%80%93Vo_hash_function

Parameters

data	read-only pointer to the data that will be hashed
dataSize	length of the data, in bytes. Usually this can be ignored unless the data is variable in length.

Returns

corresponding hash code.

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