134 lines
5.3 KiB
C++
134 lines
5.3 KiB
C++
#pragma once
|
|
|
|
////////////////////////////////////////////////////////////////////////////////
|
|
// The MIT License (MIT)
|
|
//
|
|
// Copyright (c) 2017 Nicholas Frechette & Animation Compression Library contributors
|
|
//
|
|
// Permission is hereby granted, free of charge, to any person obtaining a copy
|
|
// of this software and associated documentation files (the "Software"), to deal
|
|
// in the Software without restriction, including without limitation the rights
|
|
// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
|
|
// copies of the Software, and to permit persons to whom the Software is
|
|
// furnished to do so, subject to the following conditions:
|
|
//
|
|
// The above copyright notice and this permission notice shall be included in all
|
|
// copies or substantial portions of the Software.
|
|
//
|
|
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
|
|
// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
|
|
// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
|
|
// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
|
|
// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
|
|
// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
|
|
// SOFTWARE.
|
|
////////////////////////////////////////////////////////////////////////////////
|
|
|
|
#include "acl/core/impl/compiler_utils.h"
|
|
|
|
#include <cstdint>
|
|
#include <cstring>
|
|
#include <type_traits>
|
|
|
|
ACL_IMPL_FILE_PRAGMA_PUSH
|
|
|
|
namespace acl
|
|
{
|
|
namespace hash_impl
|
|
{
|
|
////////////////////////////////////////////////////////////////////////////////
|
|
// FNV 1a hash implementation for 32/64 bit hashes.
|
|
////////////////////////////////////////////////////////////////////////////////
|
|
template <typename ResultType, ResultType OffsetBasis, ResultType Prime>
|
|
class fnv1a_impl final
|
|
{
|
|
public:
|
|
////////////////////////////////////////////////////////////////////////////////
|
|
// Constructs a hash structures and initializes it with the offset basis.
|
|
constexpr fnv1a_impl()
|
|
: m_state(OffsetBasis)
|
|
{}
|
|
|
|
////////////////////////////////////////////////////////////////////////////////
|
|
// Updates the current hash with the new provided data.
|
|
//
|
|
// data: A pointer to the memory buffer to hash.
|
|
// size: The memory buffer size in bytes to hash.
|
|
void update(const void* data, size_t size)
|
|
{
|
|
const uint8_t* cdata = static_cast<const uint8_t*>(data);
|
|
ResultType acc = m_state;
|
|
for (size_t i = 0; i < size; ++i)
|
|
{
|
|
const ResultType next = cdata[i];
|
|
acc = (acc ^ next) * Prime;
|
|
}
|
|
m_state = acc;
|
|
}
|
|
|
|
////////////////////////////////////////////////////////////////////////////////
|
|
// Returns the current hash digest value.
|
|
constexpr ResultType digest() const { return m_state; }
|
|
|
|
private:
|
|
static_assert(std::is_unsigned<ResultType>::value, "need unsigned integer");
|
|
|
|
// The running hash digest value.
|
|
ResultType m_state;
|
|
};
|
|
}
|
|
|
|
////////////////////////////////////////////////////////////////////////////////
|
|
// A 32 bit hash instance type
|
|
using fnv1a_32 = hash_impl::fnv1a_impl<uint32_t, 2166136261U, 16777619U>;
|
|
|
|
////////////////////////////////////////////////////////////////////////////////
|
|
// A 64 bit hash instance type
|
|
using fnv1a_64 = hash_impl::fnv1a_impl<uint64_t, 14695981039346656037ULL, 1099511628211ULL>;
|
|
|
|
////////////////////////////////////////////////////////////////////////////////
|
|
// Returns the 32 bit hash of the provided buffer and size in bytes.
|
|
inline uint32_t hash32(const void* buffer, size_t buffer_size)
|
|
{
|
|
fnv1a_32 hashfn = fnv1a_32();
|
|
hashfn.update(buffer, buffer_size);
|
|
return hashfn.digest();
|
|
}
|
|
|
|
////////////////////////////////////////////////////////////////////////////////
|
|
// Returns the 32 bit hash of the provided element.
|
|
template<typename ElementType>
|
|
inline uint32_t hash32(const ElementType& element) { return hash32(&element, sizeof(ElementType)); }
|
|
|
|
////////////////////////////////////////////////////////////////////////////////
|
|
// Returns the 32 bit hash of the provided string.
|
|
// The null terminator not included in the hash.
|
|
inline uint32_t hash32(const char* str) { return hash32(str, std::strlen(str)); }
|
|
|
|
////////////////////////////////////////////////////////////////////////////////
|
|
// Returns the 64 bit hash of the provided buffer and size in bytes.
|
|
inline uint64_t hash64(const void* buffer, size_t buffer_size)
|
|
{
|
|
fnv1a_64 hashfn = fnv1a_64();
|
|
hashfn.update(buffer, buffer_size);
|
|
return hashfn.digest();
|
|
}
|
|
|
|
////////////////////////////////////////////////////////////////////////////////
|
|
// Returns the 64 bit hash of the provided element.
|
|
template<typename ElementType>
|
|
inline uint64_t hash64(const ElementType& element) { return hash64(&element, sizeof(ElementType)); }
|
|
|
|
////////////////////////////////////////////////////////////////////////////////
|
|
// Returns the 64 bit hash of the provided string.
|
|
// The null terminator not included in the hash.
|
|
inline uint64_t hash64(const char* str) { return hash64(str, std::strlen(str)); }
|
|
|
|
////////////////////////////////////////////////////////////////////////////////
|
|
// Combines two hashes into a new one.
|
|
inline uint32_t hash_combine(uint32_t hash_a, uint32_t hash_b) { return (hash_a ^ hash_b) * 16777619U; }
|
|
inline uint64_t hash_combine(uint64_t hash_a, uint64_t hash_b) { return (hash_a ^ hash_b) * 1099511628211ULL; }
|
|
}
|
|
|
|
ACL_IMPL_FILE_PRAGMA_POP
|