hash.h File Reference

#include <stdint.h>
#include <stddef.h>

Go to the source code of this file.

Macros
#define	HASH32_IV   (uint32_t)(2166136261u)
	1) CRC64/ECMA182 algorithm implementation (no tables version, slow but memory-efficient 2) Optimized variation of the FNV-1a hash algorithm.
#define	HASH32_SLASH   (uint32_t)(0x2a0c975eu)
#define	HASH64_IV   0ULL

Functions
uint32_t	hash32 (uint32_t prev_hash, uint8_t const *data, size_t len)
	Compute FNV-1a hash over a byte buffer.
uint64_t	hash64 (uint64_t prev_hash, void const *data, size_t len)
	Compute CRC64/ECMA182 hash over a byte buffer.

Macro Definition Documentation

HASH32_IV

#define HASH32_IV   (uint32_t)(2166136261u)

1) CRC64/ECMA182 algorithm implementation (no tables version, slow but memory-efficient 2) Optimized variation of the FNV-1a hash algorithm.

Init vector for 32bit hash

Definition at line 28 of file hash.h.

Referenced by inode_lookup(), and inode_populate().

HASH32_SLASH

#define HASH32_SLASH   (uint32_t)(0x2a0c975eu)

Hash32 value of a single-character C-string "/". NOTE: must be recomputed if hash32 algo is changed!

Definition at line 29 of file hash.h.

Referenced by inode_mount().

HASH64_IV

#define HASH64_IV   0ULL

Init vector for 64bit hash

Definition at line 30 of file hash.h.

Function Documentation

hash32()

uint32_t hash32	(	uint32_t	prev_hash,
		const uint8_t *	data,
		size_t	len )

Compute FNV-1a hash over a byte buffer.

This function supports incremental hashing:

h = hash32(HASH32_IV, data1, len1);
h = hash32(h,        data2, len2);
h = hash32(h,        data3, len3);
....

Parameters

prev_hash	initial hash state (use HASH32_IV for fresh hash)
data	Input byte buffer
len	Length of input buffer

Returns

Updated 32-bit FNV-1a hash

This function supports incremental hashing:

h = hash32(HASH32_IV, data1, len1);
h = hash32(h,        data2, len2);
h = hash32(h,        data3, len3);
....

Parameters

prev_hash	previous hash value (use HASH32_IV for fresh hash)
data	Input byte buffer
len	Length of input buffer

Returns

Updated 32-bit FNV-1a hash

Definition at line 79 of file hash.c.

References HASH32_CSTEP, HASH32_PSTEP, and HASH32_RETURN_IF_DONE.

Referenced by inode_lookup(), and inode_populate().

hash64()

uint64_t hash64	(	uint64_t	prev_crc,
		void const *	buffer0,
		size_t	buf_len )

Compute CRC64/ECMA182 hash over a byte buffer.

CRC-64/ECMA-182 algoritm.

This function supports incremental hashing:

h = hash64(HASH64_IV, data1, len1);
h = hash64(h,        data2, len2);
h = hash64(h,        data3, len3);
....

Parameters

prev_hash	initial hash state (use HASH32_IV for fresh hash)
data	Input byte buffer
len	Length of input buffer

Returns

Updated 64-bit CRC64 sum

Compute CRC64/ECMA182 hash over a byte buffer.

Used for data integrity verification This is the reference software implementation of 64bit CRC, no tables. It is slower than table version but it does not use extra ram and speed here is not an issue as this functions is usually called by tarfs_fsck() code

Definition at line 163 of file hash.c.

Referenced by tar_baddata().