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annotate CSP2/CSP2_env/env-d9b9114564458d9d-741b3de822f2aaca6c6caa4325c4afce/include/python3.8/pyhash.h @ 69:33d812a61356

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planemo upload commit 2e9511a184a1ca667c7be0c6321a36dc4e3d116d
author jpayne
date Tue, 18 Mar 2025 17:55:14 -0400
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jpayne@69 1 #ifndef Py_HASH_H
jpayne@69 2
jpayne@69 3 #define Py_HASH_H
jpayne@69 4 #ifdef __cplusplus
jpayne@69 5 extern "C" {
jpayne@69 6 #endif
jpayne@69 7
jpayne@69 8 /* Helpers for hash functions */
jpayne@69 9 #ifndef Py_LIMITED_API
jpayne@69 10 PyAPI_FUNC(Py_hash_t) _Py_HashDouble(double);
jpayne@69 11 PyAPI_FUNC(Py_hash_t) _Py_HashPointer(void*);
jpayne@69 12 PyAPI_FUNC(Py_hash_t) _Py_HashBytes(const void*, Py_ssize_t);
jpayne@69 13 #endif
jpayne@69 14
jpayne@69 15 /* Prime multiplier used in string and various other hashes. */
jpayne@69 16 #define _PyHASH_MULTIPLIER 1000003UL /* 0xf4243 */
jpayne@69 17
jpayne@69 18 /* Parameters used for the numeric hash implementation. See notes for
jpayne@69 19 _Py_HashDouble in Python/pyhash.c. Numeric hashes are based on
jpayne@69 20 reduction modulo the prime 2**_PyHASH_BITS - 1. */
jpayne@69 21
jpayne@69 22 #if SIZEOF_VOID_P >= 8
jpayne@69 23 # define _PyHASH_BITS 61
jpayne@69 24 #else
jpayne@69 25 # define _PyHASH_BITS 31
jpayne@69 26 #endif
jpayne@69 27
jpayne@69 28 #define _PyHASH_MODULUS (((size_t)1 << _PyHASH_BITS) - 1)
jpayne@69 29 #define _PyHASH_INF 314159
jpayne@69 30 #define _PyHASH_NAN 0
jpayne@69 31 #define _PyHASH_IMAG _PyHASH_MULTIPLIER
jpayne@69 32
jpayne@69 33
jpayne@69 34 /* hash secret
jpayne@69 35 *
jpayne@69 36 * memory layout on 64 bit systems
jpayne@69 37 * cccccccc cccccccc cccccccc uc -- unsigned char[24]
jpayne@69 38 * pppppppp ssssssss ........ fnv -- two Py_hash_t
jpayne@69 39 * k0k0k0k0 k1k1k1k1 ........ siphash -- two uint64_t
jpayne@69 40 * ........ ........ ssssssss djbx33a -- 16 bytes padding + one Py_hash_t
jpayne@69 41 * ........ ........ eeeeeeee pyexpat XML hash salt
jpayne@69 42 *
jpayne@69 43 * memory layout on 32 bit systems
jpayne@69 44 * cccccccc cccccccc cccccccc uc
jpayne@69 45 * ppppssss ........ ........ fnv -- two Py_hash_t
jpayne@69 46 * k0k0k0k0 k1k1k1k1 ........ siphash -- two uint64_t (*)
jpayne@69 47 * ........ ........ ssss.... djbx33a -- 16 bytes padding + one Py_hash_t
jpayne@69 48 * ........ ........ eeee.... pyexpat XML hash salt
jpayne@69 49 *
jpayne@69 50 * (*) The siphash member may not be available on 32 bit platforms without
jpayne@69 51 * an unsigned int64 data type.
jpayne@69 52 */
jpayne@69 53 #ifndef Py_LIMITED_API
jpayne@69 54 typedef union {
jpayne@69 55 /* ensure 24 bytes */
jpayne@69 56 unsigned char uc[24];
jpayne@69 57 /* two Py_hash_t for FNV */
jpayne@69 58 struct {
jpayne@69 59 Py_hash_t prefix;
jpayne@69 60 Py_hash_t suffix;
jpayne@69 61 } fnv;
jpayne@69 62 /* two uint64 for SipHash24 */
jpayne@69 63 struct {
jpayne@69 64 uint64_t k0;
jpayne@69 65 uint64_t k1;
jpayne@69 66 } siphash;
jpayne@69 67 /* a different (!) Py_hash_t for small string optimization */
jpayne@69 68 struct {
jpayne@69 69 unsigned char padding[16];
jpayne@69 70 Py_hash_t suffix;
jpayne@69 71 } djbx33a;
jpayne@69 72 struct {
jpayne@69 73 unsigned char padding[16];
jpayne@69 74 Py_hash_t hashsalt;
jpayne@69 75 } expat;
jpayne@69 76 } _Py_HashSecret_t;
jpayne@69 77 PyAPI_DATA(_Py_HashSecret_t) _Py_HashSecret;
jpayne@69 78 #endif
jpayne@69 79
jpayne@69 80 #ifdef Py_DEBUG
jpayne@69 81 PyAPI_DATA(int) _Py_HashSecret_Initialized;
jpayne@69 82 #endif
jpayne@69 83
jpayne@69 84
jpayne@69 85 /* hash function definition */
jpayne@69 86 #ifndef Py_LIMITED_API
jpayne@69 87 typedef struct {
jpayne@69 88 Py_hash_t (*const hash)(const void *, Py_ssize_t);
jpayne@69 89 const char *name;
jpayne@69 90 const int hash_bits;
jpayne@69 91 const int seed_bits;
jpayne@69 92 } PyHash_FuncDef;
jpayne@69 93
jpayne@69 94 PyAPI_FUNC(PyHash_FuncDef*) PyHash_GetFuncDef(void);
jpayne@69 95 #endif
jpayne@69 96
jpayne@69 97
jpayne@69 98 /* cutoff for small string DJBX33A optimization in range [1, cutoff).
jpayne@69 99 *
jpayne@69 100 * About 50% of the strings in a typical Python application are smaller than
jpayne@69 101 * 6 to 7 chars. However DJBX33A is vulnerable to hash collision attacks.
jpayne@69 102 * NEVER use DJBX33A for long strings!
jpayne@69 103 *
jpayne@69 104 * A Py_HASH_CUTOFF of 0 disables small string optimization. 32 bit platforms
jpayne@69 105 * should use a smaller cutoff because it is easier to create colliding
jpayne@69 106 * strings. A cutoff of 7 on 64bit platforms and 5 on 32bit platforms should
jpayne@69 107 * provide a decent safety margin.
jpayne@69 108 */
jpayne@69 109 #ifndef Py_HASH_CUTOFF
jpayne@69 110 # define Py_HASH_CUTOFF 0
jpayne@69 111 #elif (Py_HASH_CUTOFF > 7 || Py_HASH_CUTOFF < 0)
jpayne@69 112 # error Py_HASH_CUTOFF must in range 0...7.
jpayne@69 113 #endif /* Py_HASH_CUTOFF */
jpayne@69 114
jpayne@69 115
jpayne@69 116 /* hash algorithm selection
jpayne@69 117 *
jpayne@69 118 * The values for Py_HASH_SIPHASH24 and Py_HASH_FNV are hard-coded in the
jpayne@69 119 * configure script.
jpayne@69 120 *
jpayne@69 121 * - FNV is available on all platforms and architectures.
jpayne@69 122 * - SIPHASH24 only works on platforms that don't require aligned memory for integers.
jpayne@69 123 * - With EXTERNAL embedders can provide an alternative implementation with::
jpayne@69 124 *
jpayne@69 125 * PyHash_FuncDef PyHash_Func = {...};
jpayne@69 126 *
jpayne@69 127 * XXX: Figure out __declspec() for extern PyHash_FuncDef.
jpayne@69 128 */
jpayne@69 129 #define Py_HASH_EXTERNAL 0
jpayne@69 130 #define Py_HASH_SIPHASH24 1
jpayne@69 131 #define Py_HASH_FNV 2
jpayne@69 132
jpayne@69 133 #ifndef Py_HASH_ALGORITHM
jpayne@69 134 # ifndef HAVE_ALIGNED_REQUIRED
jpayne@69 135 # define Py_HASH_ALGORITHM Py_HASH_SIPHASH24
jpayne@69 136 # else
jpayne@69 137 # define Py_HASH_ALGORITHM Py_HASH_FNV
jpayne@69 138 # endif /* uint64_t && uint32_t && aligned */
jpayne@69 139 #endif /* Py_HASH_ALGORITHM */
jpayne@69 140
jpayne@69 141 #ifdef __cplusplus
jpayne@69 142 }
jpayne@69 143 #endif
jpayne@69 144
jpayne@69 145 #endif /* !Py_HASH_H */