qhash.c File Reference

Hash APIs. More...

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Functions
bool	qhashmd5 (const void *data, size_t nbytes, void *retbuf)
	Calculate 128-bit(16-bytes) MD5 hash.
bool	qhashmd5_file (const char *filepath, off_t offset, ssize_t nbytes, void *retbuf)
	Get 128-bit MD5 hash of a file contents.
uint32_t	qhashfnv1_32 (const void *data, size_t nbytes)
	Get 32-bit FNV1 hash.
uint64_t	qhashfnv1_64 (const void *data, size_t nbytes)
	Get 64-bit FNV1 hash integer.
uint32_t	qhashmurmur3_32 (const void *data, size_t nbytes)
	Get 32-bit Murmur3 hash.
bool	qhashmurmur3_128 (const void *data, size_t nbytes, void *retbuf)
	Get 128-bit Murmur3 hash.

Detailed Description

Hash APIs.

Definition in file qhash.c.

Function Documentation

qhashmd5()

bool qhashmd5	(	const void *	data,
		size_t	nbytes,
		void *	retbuf
	)

Calculate 128-bit(16-bytes) MD5 hash.

Parameters

data	source object
nbytes	size of data
retbuf	user buffer. It must be at leat 16-bytes long.

Returns

true if successful, otherwise false.

// get MD5
unsigned char md5hash[16];
qhashmd5((void*)"hello", 5, md5hash);
 
// hex encode
char *md5ascii = qhex_encode(md5hash, 16);
printf("Hex encoded MD5: %s\n", md5ascii);
free(md5ascii);

Definition at line 67 of file qhash.c.

qhashmd5_file()

bool qhashmd5_file	(	const char *	filepath,
		off_t	offset,
		ssize_t	nbytes,
		void *	retbuf
	)

Get 128-bit MD5 hash of a file contents.

Parameters

filepath	file path
offset	start offset. Set to 0 to digest from beginning of file.
nbytes	number of bytes to digest. Set to 0 to digest until end of file.
retbuf	user buffer. It must be at leat 16-bytes long.

Returns

true if successful, otherwise false.

unsigned char md5hash[16];
qhashmd5_file("/tmp/test.dat", 0, 0, md5hash);

Definition at line 97 of file qhash.c.

qhashfnv1_32()

uint32_t qhashfnv1_32	(	const void *	data,
		size_t	nbytes
	)

Get 32-bit FNV1 hash.

Parameters

data	source data
nbytes	size of data

Returns

32-bit unsigned hash value.

uint32_t hashval = qhashfnv1_32((void*)"hello", 5);

Fowler/Noll/Vo hash
 
The basis of this hash algorithm was taken from an idea sent as reviewer
comments to the IEEE POSIX P1003.2 committee by:
 
    Phong Vo (http://www.research.att.com/info/kpv/)
    Glenn Fowler (http://www.research.att.com/~gsf/)
 
In a subsequent ballot round:
 
    Landon Curt Noll (http://www.isthe.com/chongo/)
 
improved on their algorithm.  Some people tried this hash and found that
it worked rather well. In an EMail message to Landon, they named it the
``Fowler/Noll/Vo'' or FNV hash.
 
FNV hashes are designed to be fast while maintaining a low collision rate.
The FNV speed allows one to quickly hash lots of data while maintaining
a reasonable collision rate.  See:
 
    http://www.isthe.com/chongo/tech/comp/fnv/index.html
 
for more details as well as other forms of the FNV hash.

Definition at line 192 of file qhash.c.

qhashfnv1_64()

uint64_t qhashfnv1_64	(	const void *	data,
		size_t	nbytes
	)

Get 64-bit FNV1 hash integer.

Parameters

data	source data
nbytes	size of data

Returns

64-bit unsigned hash value.

uint64_t fnv64 = qhashfnv1_64((void*)"hello", 5);

Definition at line 223 of file qhash.c.

qhashmurmur3_32()

uint32_t qhashmurmur3_32	(	const void *	data,
		size_t	nbytes
	)

Get 32-bit Murmur3 hash.

Parameters

data	source data
nbytes	size of data

Returns

32-bit unsigned hash value.

uint32_t hashval = qhashmurmur3_32((void*)"hello", 5);

MurmurHash3 was created by Austin Appleby  in 2008. The initial
implementation was published in C++ and placed in the public.
  https://sites.google.com/site/murmurhash/
Seungyoung Kim has ported its implementation into C language
in 2012 and published it as a part of qLibc component.

Definition at line 263 of file qhash.c.

qhashmurmur3_128()

bool qhashmurmur3_128	(	const void *	data,
		size_t	nbytes,
		void *	retbuf
	)

Get 128-bit Murmur3 hash.

Parameters

data	source data
nbytes	size of data
retbuf	user buffer. It must be at leat 16-bytes long.

Returns

true if successful, otherwise false.

// get 128-bit Murmur3 hash.
unsigned char hash[16];
qhashmurmur3_128((void*)"hello", 5, hash);
 
// hex encode
char *ascii = qhex_encode(hash, 16);
printf("Hex encoded Murmur3: %s\n", ascii);
free(ascii);

Definition at line 335 of file qhash.c.