mgl_hash_fnv1a.h

[詳解]

// SPDX-License-Identifier: Zlib
/* ------------------------------------------------------------------------- */
/* ------------------------------------------------------------------------- */
 
#ifndef INCGUARD_MGL_HASH_FNV1A_H_1607309087
#define INCGUARD_MGL_HASH_FNV1A_H_1607309087
 
#include <cstdint>
 
namespace MGL::Hash
{
constexpr uint32_t kFNV1aDefaultValue32  = 0xA3F6C23E;
constexpr uint32_t kFNV1aPrime32         = 0x1000193;
constexpr uint64_t kFNV1aDefaultValue64  = 0xC18F36FE9A341BC5;
constexpr uint64_t kFNV1aPrime64         = 0x100000001B3;
 
 
/* ------------------------------------------------------------------------- */
/* ------------------------------------------------------------------------- */
constexpr uint32_t FNV1a(const char *str, const uint32_t value = Hash::kFNV1aDefaultValue32) noexcept
{
    if (str[0] == '\0')
    {
        return value;
    }
    
    return FNV1a(&str[1], (value ^ static_cast<uint32_t>(str[0])) * Hash::kFNV1aPrime32);
}
 
 
/* ------------------------------------------------------------------------- */
/* ------------------------------------------------------------------------- */
constexpr uint64_t FNV1a64(const char *str, const uint64_t value = Hash::kFNV1aDefaultValue64) noexcept
{
    if (str[0] == '\0')
    {
        return value;
    }
    
    return FNV1a64(&str[1], (value ^ static_cast<uint64_t>(str[0])) * Hash::kFNV1aPrime64);
}
}   // namespace MGL::Hash
#endif  // INCGUARD_MGL_HASH_FNV1A_H_1607309087
 
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