#ifndef Py_HASH_H

#define Py_HASH_H
#ifdef __cplusplus
extern "C" {
#endif

/* Helpers for hash functions */
#ifndef Py_LIMITED_API
PyAPI_FUNC(Py_hash_t) _Py_HashDouble(double);
PyAPI_FUNC(Py_hash_t) _Py_HashPointer(void*);
PyAPI_FUNC(Py_hash_t) _Py_HashBytes(const void*, Py_ssize_t);
#endif

/* Prime multiplier used in string and various other hashes. */
#define _PyHASH_MULTIPLIER 1000003UL  /* 0xf4243 */

/* Parameters used for the numeric hash implementation.  See notes for
   _Py_HashDouble in Objects/object.c.  Numeric hashes are based on
   reduction modulo the prime 2**_PyHASH_BITS - 1. */

#if SIZEOF_VOID_P >= 8
#  define _PyHASH_BITS 61
#else
#  define _PyHASH_BITS 31
#endif

#define _PyHASH_MODULUS (((size_t)1  7 || Py_HASH_CUTOFF < 0)
#  error Py_HASH_CUTOFF must in range 0...7.
#endif /* Py_HASH_CUTOFF */


/* hash algorithm selection
 *
 * The values for Py_HASH_SIPHASH24 and Py_HASH_FNV are hard-coded in the
 * configure script.
 *
 * - FNV is available on all platforms and architectures.
 * - SIPHASH24 only works on plaforms that provide PY_UINT64_T and doesn't
 *   require aligned memory for integers.
 * - With EXTERNAL embedders can provide an alternative implementation with::
 *
 *     PyHash_FuncDef PyHash_Func = {...};
 *
 * XXX: Figure out __declspec() for extern PyHash_FuncDef.
 */
#define Py_HASH_EXTERNAL 0
#define Py_HASH_SIPHASH24 1
#define Py_HASH_FNV 2

#ifndef Py_HASH_ALGORITHM
#  if (defined(PY_UINT64_T) && defined(PY_UINT32_T) \
       && !defined(HAVE_ALIGNED_REQUIRED))
#    define Py_HASH_ALGORITHM Py_HASH_SIPHASH24
#  else
#    define Py_HASH_ALGORITHM Py_HASH_FNV
#  endif /* uint64_t && uint32_t && aligned */
#endif /* Py_HASH_ALGORITHM */

#ifdef __cplusplus
}
#endif

#endif /* !Py_HASH_H */