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hashers.h File Reference
#include <stddef.h>#include <stdint.h>#include <string.h>#include <derive-c/algorithm/hash/murmurhash.h>#include <derive-c/core/prelude.h>
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Macros | |
| #define | ALWAYS_COLLIDE(type) |
| The worst possible hash, for testing purposes. | |
| #define | ID(type) |
| #define | MURMURHASH_3_FMIx64(type) |
| #define | INT_HASHERS(_apply) |
| #define | MURMURHASH_DEFAULT_SEED 0x9747b28c |
| #define | STRING_SIZES(_apply) |
| #define | MURMURHASH_STRING_FIXED_SIZE(size) |
Functions | |
| size_t | hash_murmurhash_string (const char *str) |
| static size_t | hash_combine (size_t seed, size_t h) |
Macro Definition Documentation
◆ ALWAYS_COLLIDE
| #define ALWAYS_COLLIDE | ( | type | ) |
Value:
static size_t hash_always_collide_##type(type const* key) { \
(void)key; \
return 0; \
}
The worst possible hash, for testing purposes.
Interesting literature:
Definition at line 13 of file hashers.h.
13#define ALWAYS_COLLIDE(type) \
14 static size_t hash_always_collide_##type(type const* key) { \
15 (void)key; \
16 return 0; \
17 }
◆ ID
| #define ID | ( | type | ) |
Value:
static size_t hash_id_##type(type const* key) { \
STATIC_ASSERT(sizeof(type) <= sizeof(size_t), \
"ID hashing only supports up to size_t integers"); \
return (size_t)(*key); \
}
No hashing, just returns the integer value. For most circumstances with a key as a single integer, this is a good option.
Definition at line 21 of file hashers.h.
21#define ID(type) \
22 static size_t hash_id_##type(type const* key) { \
23 STATIC_ASSERT(sizeof(type) <= sizeof(size_t), \
24 "ID hashing only supports up to size_t integers"); \
25 return (size_t)(*key); \
26 }
◆ INT_HASHERS
| #define INT_HASHERS | ( | _apply | ) |
Value:
_apply(int8_t ) \
_apply(int16_t ) \
_apply(int32_t ) \
_apply(int64_t ) \
_apply(uint8_t ) \
_apply(uint16_t) \
_apply(uint32_t) \
_apply(uint64_t)
Definition at line 40 of file hashers.h.
40#define INT_HASHERS(_apply) \
41 _apply(int8_t ) \
42 _apply(int16_t ) \
43 _apply(int32_t ) \
44 _apply(int64_t ) \
45 _apply(uint8_t ) \
46 _apply(uint16_t) \
47 _apply(uint32_t) \
48 _apply(uint64_t)
◆ MURMURHASH_3_FMIx64
| #define MURMURHASH_3_FMIx64 | ( | type | ) |
Value:
static size_t hash_murmurhash3_##type(type const* key) { \
STATIC_ASSERT(sizeof(type) <= sizeof(uint64_t), \
"MurmurHash3 only supports up to 64-bit integers"); \
return (size_t)derive_c_fmix64((uint64_t)(*key)); \
}
Using MurmurHash3's finalizer for integer hashing.
Definition at line 32 of file hashers.h.
32#define MURMURHASH_3_FMIx64(type) \
33 static size_t hash_murmurhash3_##type(type const* key) { \
34 STATIC_ASSERT(sizeof(type) <= sizeof(uint64_t), \
35 "MurmurHash3 only supports up to 64-bit integers"); \
36 return (size_t)derive_c_fmix64((uint64_t)(*key)); \
37 }
◆ MURMURHASH_DEFAULT_SEED
◆ MURMURHASH_STRING_FIXED_SIZE
| #define MURMURHASH_STRING_FIXED_SIZE | ( | size | ) |
Value:
}
size_t derive_c_murmurhash(const void *key, int32_t len, uint32_t seed)
Definition murmurhash.h:351
Definition at line 78 of file hashers.h.
78#define MURMURHASH_STRING_FIXED_SIZE(size) \
79 static size_t hash_murmurhash_string_##size(const char str[size]) { \
80 return derive_c_murmurhash(str, size, MURMURHASH_DEFAULT_SEED); \
81 }
◆ STRING_SIZES
| #define STRING_SIZES | ( | _apply | ) |
Function Documentation
◆ hash_combine()
|
inlinestatic |
- Examples
- container/map/decomposed.c.
Definition at line 88 of file hashers.h.
88 {
89 // 0x9e3779b97f4a7c15 is 64-bit fractional part of the golden ratio;
90 // “+ (seed<<6) + (seed>>2)” mixes seed’s bits
91 return seed ^ (h + 0x9e3779b97f4a7c15ULL + (seed << 6) + (seed >> 2));
92}
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◆ hash_murmurhash_string()
| size_t hash_murmurhash_string | ( | const char * | str | ) |
- Examples
- container/map/decomposed.c.
Definition at line 62 of file hashers.h.
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