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https://github.com/python/cpython
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828451dfde
* Implement _Py_HashPointerRaw() as a static inline function. * Add Py_HashPointer() tests to test_capi.test_hash. * Keep _Py_HashPointer() function as an alias to Py_HashPointer().
108 lines
2.7 KiB
C
108 lines
2.7 KiB
C
#ifndef Py_INTERNAL_PYHASH_H
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#define Py_INTERNAL_PYHASH_H
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#ifndef Py_BUILD_CORE
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# error "this header requires Py_BUILD_CORE define"
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#endif
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// Similar to Py_HashPointer(), but don't replace -1 with -2.
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static inline Py_hash_t
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_Py_HashPointerRaw(const void *ptr)
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{
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uintptr_t x = (uintptr_t)ptr;
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Py_BUILD_ASSERT(sizeof(x) == sizeof(ptr));
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// Bottom 3 or 4 bits are likely to be 0; rotate x by 4 to the right
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// to avoid excessive hash collisions for dicts and sets.
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x = (x >> 4) | (x << (8 * sizeof(uintptr_t) - 4));
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Py_BUILD_ASSERT(sizeof(x) == sizeof(Py_hash_t));
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return (Py_hash_t)x;
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}
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// Export for '_datetime' shared extension
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PyAPI_FUNC(Py_hash_t) _Py_HashBytes(const void*, Py_ssize_t);
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/* Hash secret
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*
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* memory layout on 64 bit systems
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* cccccccc cccccccc cccccccc uc -- unsigned char[24]
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* pppppppp ssssssss ........ fnv -- two Py_hash_t
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* k0k0k0k0 k1k1k1k1 ........ siphash -- two uint64_t
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* ........ ........ ssssssss djbx33a -- 16 bytes padding + one Py_hash_t
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* ........ ........ eeeeeeee pyexpat XML hash salt
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*
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* memory layout on 32 bit systems
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* cccccccc cccccccc cccccccc uc
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* ppppssss ........ ........ fnv -- two Py_hash_t
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* k0k0k0k0 k1k1k1k1 ........ siphash -- two uint64_t (*)
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* ........ ........ ssss.... djbx33a -- 16 bytes padding + one Py_hash_t
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* ........ ........ eeee.... pyexpat XML hash salt
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*
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* (*) The siphash member may not be available on 32 bit platforms without
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* an unsigned int64 data type.
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*/
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typedef union {
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/* ensure 24 bytes */
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unsigned char uc[24];
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/* two Py_hash_t for FNV */
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struct {
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Py_hash_t prefix;
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Py_hash_t suffix;
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} fnv;
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/* two uint64 for SipHash24 */
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struct {
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uint64_t k0;
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uint64_t k1;
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} siphash;
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/* a different (!) Py_hash_t for small string optimization */
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struct {
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unsigned char padding[16];
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Py_hash_t suffix;
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} djbx33a;
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struct {
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unsigned char padding[16];
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Py_hash_t hashsalt;
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} expat;
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} _Py_HashSecret_t;
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// Export for '_elementtree' shared extension
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PyAPI_DATA(_Py_HashSecret_t) _Py_HashSecret;
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#ifdef Py_DEBUG
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extern int _Py_HashSecret_Initialized;
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#endif
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struct pyhash_runtime_state {
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struct {
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#ifndef MS_WINDOWS
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int fd;
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dev_t st_dev;
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ino_t st_ino;
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#else
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// This is a placeholder so the struct isn't empty on Windows.
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int _not_used;
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#endif
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} urandom_cache;
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};
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#ifndef MS_WINDOWS
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# define _py_urandom_cache_INIT \
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{ \
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.fd = -1, \
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}
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#else
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# define _py_urandom_cache_INIT {0}
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#endif
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#define pyhash_state_INIT \
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{ \
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.urandom_cache = _py_urandom_cache_INIT, \
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}
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extern uint64_t _Py_KeyedHash(uint64_t key, const void *src, Py_ssize_t src_sz);
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#endif // !Py_INTERNAL_PYHASH_H
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