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//    notice, this list of conditions and the following disclaimer.
//  * Redistributions in binary form must reproduce the above copyright
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//    contributors may be used to endorse or promote products derived
//    from this software without specific prior written permission.
//
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// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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// Copyright (c) 2008-2024 NVIDIA Corporation. All rights reserved.

#ifndef NV_NSFOUNDATION_NSHASH_H
#define NV_NSFOUNDATION_NSHASH_H

#include "Ns.h"
#include "NsBasicTemplates.h"

#if NV_VC
#pragma warning(push)
#pragma warning(disable : 4302)
#endif

#if NV_LINUX
#include "NvSimpleTypes.h"
#endif

/*!
Central definition of hash functions
*/

namespace nvidia
{
namespace shdfnd
{
// Hash functions

// Thomas Wang's 32 bit mix
// http://www.cris.com/~Ttwang/tech/inthash.htm
NV_FORCE_INLINE uint32_t hash(const uint32_t key)
{
    uint32_t k = key;
    k += ~(k << 15);
    k ^= (k >> 10);
    k += (k << 3);
    k ^= (k >> 6);
    k += ~(k << 11);
    k ^= (k >> 16);
    return uint32_t(k);
}

NV_FORCE_INLINE uint32_t hash(const int32_t key)
{
    return hash(uint32_t(key));
}

// Thomas Wang's 64 bit mix
// http://www.cris.com/~Ttwang/tech/inthash.htm
NV_FORCE_INLINE uint32_t hash(const uint64_t key)
{
    uint64_t k = key;
    k += ~(k << 32);
    k ^= (k >> 22);
    k += ~(k << 13);
    k ^= (k >> 8);
    k += (k << 3);
    k ^= (k >> 15);
    k += ~(k << 27);
    k ^= (k >> 31);
    return uint32_t(UINT32_MAX & k);
}

#if NV_APPLE_FAMILY
// hash for size_t, to make gcc happy
NV_INLINE uint32_t hash(const size_t key)
{
#if NV_P64_FAMILY
    return hash(uint64_t(key));
#else
    return hash(uint32_t(key));
#endif
}
#endif

// Hash function for pointers
NV_INLINE uint32_t hash(const void* ptr)
{
#if NV_P64_FAMILY
    return hash(uint64_t(ptr));
#else
    return hash(uint32_t(UINT32_MAX & size_t(ptr)));
#endif
}

// Hash function for pairs
template <typename F, typename S>
NV_INLINE uint32_t hash(const Pair<F, S>& p)
{
    uint32_t seed = 0x876543;
    uint32_t m = 1000007;
    return hash(p.second) ^ (m * (hash(p.first) ^ (m * seed)));
}

// hash object for hash map template parameter
template <class Key>
struct Hash
{
    uint32_t operator()(const Key& k) const
    {
        return hash(k);
    }
    bool equal(const Key& k0, const Key& k1) const
    {
        return k0 == k1;
    }
};

// specialization for strings
template <>
struct Hash<const char*>
{
  public:
    uint32_t operator()(const char* _string) const
    {
        // "DJB" string hash
        const uint8_t* string = reinterpret_cast<const uint8_t*>(_string);
        uint32_t h = 5381;
        for(const uint8_t* ptr = string; *ptr; ptr++)
            h = ((h << 5) + h) ^ uint32_t(*ptr);
        return h;
    }
    bool equal(const char* string0, const char* string1) const
    {
        return !strcmp(string0, string1);
    }
};

} // namespace shdfnd
} // namespace nvidia

#if NV_VC
#pragma warning(pop)
#endif

#endif // #ifndef NV_NSFOUNDATION_NSHASH_H
