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#include "compat/defs.hpp"
#include "hash.hpp"
#include <Corrade/Containers/StringView.h>
#include <bit>
#include <utility>
namespace floormat {
namespace {
using namespace floormat::Hash;
[[maybe_unused]]
CORRADE_ALWAYS_INLINE size_t fnvhash_uint_32(uint32_t x)
{
constexpr auto params = fnvhash_params<sizeof(size_t)*8>{};
constexpr auto a = params.a, b = params.b;
auto hash = a;
const auto* str = (const char*)&x;
hash *= b; hash ^= (uint8_t)*str++; // 0
hash *= b; hash ^= (uint8_t)*str++; // 1
hash *= b; hash ^= (uint8_t)*str++; // 2
hash *= b; hash ^= (uint8_t)*str++; // 3
return hash;
}
CORRADE_ALWAYS_INLINE size_t fnvhash_uint_64(uint64_t x)
{
constexpr auto params = fnvhash_params<sizeof(std::common_type_t<size_t>)*8>{};
constexpr auto a = params.a, b = params.b;
auto hash = a;
const auto* str = (const char*)&x;
hash *= b; hash ^= (uint8_t)*str++; // 0
hash *= b; hash ^= (uint8_t)*str++; // 1
hash *= b; hash ^= (uint8_t)*str++; // 2
hash *= b; hash ^= (uint8_t)*str++; // 3
hash *= b; hash ^= (uint8_t)*str++; // 4
hash *= b; hash ^= (uint8_t)*str++; // 5
hash *= b; hash ^= (uint8_t)*str++; // 6
hash *= b; hash ^= (uint8_t)*str++; // 7
return hash;
}
} // namespace
uint32_t hash_32(const void* buf, size_t size) noexcept
{
constexpr auto params = fnvhash_params<32>{};
constexpr auto a = params.a, b = params.b;
auto hash = a;
const auto *str = (const char*)buf, *const end = str + size;
fm_UNROLL_4
for (; str != end; ++str)
{
hash *= b;
hash ^= (uint8_t)*str;
}
return hash;
}
uint64_t hash_64(const void* buf, size_t size) noexcept
{
constexpr auto params = fnvhash_params<sizeof(size_t)*8>{};
constexpr auto a = params.a, b = params.b;
auto hash = a;
const auto *str = (const char*)buf, *const end = str + size;
fm_UNROLL_8
for (; str != end; ++str)
{
hash *= b;
hash ^= (uint8_t)*str;
}
return hash;
}
size_t hash_buf(const void* buf, size_t size) noexcept
{
#if 1
if constexpr(sizeof nullptr > 4)
return hash_64(buf, size);
else
#endif
return hash_32(buf, size);
}
size_t hash_int(uint32_t x) noexcept
{
#if 1
if constexpr(sizeof nullptr > 4)
return fnvhash_uint_64(x);
else
#endif
return fnvhash_uint_32(x);
}
size_t hash_int(uint64_t x) noexcept
{
return fnvhash_uint_64(x);
}
size_t hash_string_view::operator()(StringView s) const noexcept { return Hash::fnvhash_buf(s.data(), s.size()); }
} // namespace floormat
namespace floormat::Hash {
size_t fnvhash_buf(const void* __restrict buf, size_t size, size_t seed) noexcept
{
constexpr size_t b{fnvhash_params<sizeof nullptr*8>::b};
size_t full_rounds = size / 8, rest = size % 8;
size_t hash = seed;
const char* str = (const char*)buf;
while (full_rounds--)
{
hash *= b; hash ^= (uint8_t)*str++; // 0
hash *= b; hash ^= (uint8_t)*str++; // 1
hash *= b; hash ^= (uint8_t)*str++; // 2
hash *= b; hash ^= (uint8_t)*str++; // 3
hash *= b; hash ^= (uint8_t)*str++; // 4
hash *= b; hash ^= (uint8_t)*str++; // 5
hash *= b; hash ^= (uint8_t)*str++; // 6
hash *= b; hash ^= (uint8_t)*str++; // 7
}
switch (rest)
{
case 7: hash *= b; hash ^= (uint8_t)*str++; [[fallthrough]];
case 6: hash *= b; hash ^= (uint8_t)*str++; [[fallthrough]];
case 5: hash *= b; hash ^= (uint8_t)*str++; [[fallthrough]];
case 4: hash *= b; hash ^= (uint8_t)*str++; [[fallthrough]];
case 3: hash *= b; hash ^= (uint8_t)*str++; [[fallthrough]];
case 2: hash *= b; hash ^= (uint8_t)*str++; [[fallthrough]];
case 1: hash *= b; hash ^= (uint8_t)*str++; [[fallthrough]];
case 0: break;
default: std::unreachable();
}
return hash;
}
} // namespace floormat::Hash
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