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oplanre/djbx33a.h

Last active August 12, 2024 18:20
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Revisions

  1. oplanre revised this gist Aug 12, 2024. 1 changed file with 1 addition and 1 deletion.
    2 changes: 1 addition & 1 deletion djbx33a.h
    View file
    Original file line number Diff line number Diff line change
    @@ -1,4 +1,4 @@
    static constexpr T DJBX33A(const char *str, size_t len){
    static constexpr zend_ulong DJBX33A(const char *str, size_t len){
    zend_ulong hash = 5381;
    #if defined(_WIN32) || defined(__i386__) || defined(__x86_64__) || defined(__aarch64__)
    // Version with multiplication works better on modern CPUs
  2. oplanre revised this gist Aug 12, 2024. 1 changed file with 4 additions and 9 deletions.
    13 changes: 4 additions & 9 deletions djbx33a.h
    View file
    Original file line number Diff line number Diff line change
    @@ -1,6 +1,5 @@
    template <typename T = ULong>
    static constexpr T DJBX33A(const char *str, size_t len){
    std::make_unsigned_t<T> hash = 5381;
    zend_ulong hash = 5381;
    #if defined(_WIN32) || defined(__i386__) || defined(__x86_64__) || defined(__aarch64__)
    // Version with multiplication works better on modern CPUs
    for (; len >= 8; len -= 8, str += 8) {
    @@ -43,11 +42,7 @@ static constexpr T DJBX33A(const char *str, size_t len){
    // EMPTY_SWITCH_DEFAULT_CASE()
    }
    #endif
    if constexpr (sizeof(T) == 8) return hash | 0x8000000000000000ULL;
    if constexpr (sizeof(T) == 4) return hash | 0x80000000UL;
    static_assert(sizeof(T) == 8 || sizeof(T) == 4, "Unsupported hash size");
    }
    template <typename T, typename CharT>
    static constexpr T DJBX33A(const CharT *str, size_t len) {
    return DJBX33A<T>(reinterpret_cast<const char *>(str), len * sizeof(CharT));
    if constexpr (sizeof(zend_ulong) == 8) return hash | 0x8000000000000000ULL;
    if constexpr (sizeof(zend_ulong) == 4) return hash | 0x80000000UL;
    static_assert(sizeof(zend_ulong) == 8 || sizeof(zend_ulong) == 4, "Unsupported hash size");
    }
  3. oplanre renamed this gist Aug 12, 2024. 1 changed file with 0 additions and 0 deletions.
    0 dhbx33a.h → djbx33a.h
    View file
    File renamed without changes.
  4. oplanre created this gist Aug 12, 2024.
    53 changes: 53 additions & 0 deletions dhbx33a.h
    View file
    Original file line number Diff line number Diff line change
    @@ -0,0 +1,53 @@
    template <typename T = ULong>
    static constexpr T DJBX33A(const char *str, size_t len){
    std::make_unsigned_t<T> hash = 5381;
    #if defined(_WIN32) || defined(__i386__) || defined(__x86_64__) || defined(__aarch64__)
    // Version with multiplication works better on modern CPUs
    for (; len >= 8; len -= 8, str += 8) {
    uint64_t chunk;
    std::memcpy(&chunk, str, sizeof(chunk));
    hash = hash * 33 * 33 * 33 * 33 + ((chunk >> (8 * 0)) & 0xff) * 33 * 33 * 33 + ((chunk >> (8 * 1)) & 0xff) * 33 * 33 +
    ((chunk >> (8 * 2)) & 0xff) * 33 + ((chunk >> (8 * 3)) & 0xff);
    hash = hash * 33 * 33 * 33 * 33 + ((chunk >> (8 * 4)) & 0xff) * 33 * 33 * 33 + ((chunk >> (8 * 5)) & 0xff) * 33 * 33 +
    ((chunk >> (8 * 6)) & 0xff) * 33 + ((chunk >> (8 * 7)) & 0xff);
    }
    // Remaining bytes
    for (; len >= 4; len -= 4, str += 4) {
    hash = hash * 33 * 33 * 33 * 33 + str[0] * 33 * 33 * 33 + str[1] * 33 * 33 + str[2] * 33 + str[3];
    }
    for (; len >= 2; len -= 2, str += 2) { hash = hash * 33 * 33 * 33 + str[0] * 33 * 33 + str[1] * 33; }
    if (len == 1) { hash = hash * 33 + *str; }
    #else
    // Variant with the hash unrolled eight times
    for (; len >= 8; len -= 8) {
    hash = ((hash << 5) + hash) + *str++;
    hash = ((hash << 5) + hash) + *str++;
    hash = ((hash << 5) + hash) + *str++;
    hash = ((hash << 5) + hash) + *str++;
    hash = ((hash << 5) + hash) + *str++;
    hash = ((hash << 5) + hash) + *str++;
    hash = ((hash << 5) + hash) + *str++;
    hash = ((hash << 5) + hash) + *str++;
    }
    // Remaining bytes
    switch (len) {
    case 7: hash = ((hash << 5) + hash) + *str++; /* fallthrough... */
    case 6: hash = ((hash << 5) + hash) + *str++; /* fallthrough... */
    case 5: hash = ((hash << 5) + hash) + *str++; /* fallthrough... */
    case 4: hash = ((hash << 5) + hash) + *str++; /* fallthrough... */
    case 3: hash = ((hash << 5) + hash) + *str++; /* fallthrough... */
    case 2: hash = ((hash << 5) + hash) + *str++; /* fallthrough... */
    case 1: hash = ((hash << 5) + hash) + *str++; break;
    case 0:
    break;
    // EMPTY_SWITCH_DEFAULT_CASE()
    }
    #endif
    if constexpr (sizeof(T) == 8) return hash | 0x8000000000000000ULL;
    if constexpr (sizeof(T) == 4) return hash | 0x80000000UL;
    static_assert(sizeof(T) == 8 || sizeof(T) == 4, "Unsupported hash size");
    }
    template <typename T, typename CharT>
    static constexpr T DJBX33A(const CharT *str, size_t len) {
    return DJBX33A<T>(reinterpret_cast<const char *>(str), len * sizeof(CharT));
    }