fnv1a.h

Go to the documentation of this file.

 
#pragma once
 
 
#include <promeki/config.h>
#if PROMEKI_ENABLE_CORE
#include <cstdint>
#include <cstddef>
#include <promeki/namespace.h>
 
PROMEKI_NAMESPACE_BEGIN
 
constexpr uint64_t fnv1a(const char *s, uint64_t seed = 0xcbf29ce484222325ULL) {
        return *s ? fnv1a(s + 1, (seed ^ static_cast<uint64_t>(*s)) * 0x100000001b3ULL) : seed;
}
 
constexpr uint64_t fnv1aData(const void *data, size_t len, uint64_t seed = 0xcbf29ce484222325ULL) {
        const auto *p = static_cast<const unsigned char *>(data);
        for (size_t i = 0; i < len; ++i) {
                seed = (seed ^ static_cast<uint64_t>(p[i])) * 0x100000001b3ULL;
        }
        return seed;
}
 
constexpr uint64_t fnv1aMixCodepoint(uint64_t seed, char32_t cp) {
        constexpr uint64_t prime = 0x100000001b3ULL;
        seed = (seed ^ static_cast<uint64_t>((cp >> 0) & 0xffu)) * prime;
        seed = (seed ^ static_cast<uint64_t>((cp >> 8) & 0xffu)) * prime;
        seed = (seed ^ static_cast<uint64_t>((cp >> 16) & 0xffu)) * prime;
        seed = (seed ^ static_cast<uint64_t>((cp >> 24) & 0xffu)) * prime;
        return seed;
}
 
constexpr uint64_t fnv1aCodepoints(const char32_t *data, size_t count, uint64_t seed = 0xcbf29ce484222325ULL) {
        for (size_t i = 0; i < count; ++i) {
                seed = fnv1aMixCodepoint(seed, data[i]);
        }
        return seed;
}
 
constexpr uint64_t fnv1aLatin1AsCodepoints(const void *data, size_t len, uint64_t seed = 0xcbf29ce484222325ULL) {
        const auto *p = static_cast<const unsigned char *>(data);
        for (size_t i = 0; i < len; ++i) {
                seed = fnv1aMixCodepoint(seed, static_cast<char32_t>(p[i]));
        }
        return seed;
}
 
PROMEKI_NAMESPACE_END
 
#endif // PROMEKI_ENABLE_CORE