Add constexpr md5 hash implementation
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libs/util/include/psemek/util/md5.hpp
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libs/util/include/psemek/util/md5.hpp
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#pragma once
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#include <string_view>
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#include <array>
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#include <cstdint>
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namespace psemek::util
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{
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std::array<std::uint32_t, 4> md5_hash(std::string_view data);
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}
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libs/util/include/psemek/util/md5_inl.hpp
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libs/util/include/psemek/util/md5_inl.hpp
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#pragma once
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#include <cstdint>
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#include <string_view>
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#include <array>
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namespace psemek::util
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{
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// Constexpr MD5 hash implementation.
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// Partially based on https://github.com/Wodann/constexpr-md5-cpp/blob/master/include/md5.h
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namespace md5_detail
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{
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constexpr std::uint32_t f(std::uint32_t b, std::uint32_t c, std::uint32_t d)
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{
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return (b & c) | (~b & d);
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}
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constexpr std::uint32_t g(std::uint32_t b, std::uint32_t c, std::uint32_t d)
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{
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return (b & d) | (c & ~d);
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}
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constexpr std::uint32_t h(std::uint32_t b, std::uint32_t c, std::uint32_t d)
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{
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return b ^ c ^ d;
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}
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constexpr std::uint32_t i(std::uint32_t b, std::uint32_t c, std::uint32_t d)
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{
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return c ^ (b | ~d);
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}
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using Fn = uint32_t(*)(uint32_t, uint32_t, uint32_t);
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constexpr Fn F[4] = { f, g, h, i };
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constexpr std::uint32_t G[64] =
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{
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0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15,
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1, 6, 11, 0, 5, 10, 15, 4, 9, 14, 3, 8, 13, 2, 7, 12,
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5, 8, 11, 14, 1, 4, 7, 10, 13, 0, 3, 6, 9, 12, 15, 2,
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0, 7, 14, 5, 12, 3, 10, 1, 8, 15, 6, 13, 4, 11, 2, 9
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};
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constexpr std::uint32_t K[64] =
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{
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0xd76aa478u, 0xe8c7b756u, 0x242070dbu, 0xc1bdceeeu,
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0xf57c0fafu, 0x4787c62au, 0xa8304613u, 0xfd469501u,
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0x698098d8u, 0x8b44f7afu, 0xffff5bb1u, 0x895cd7beu,
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0x6b901122u, 0xfd987193u, 0xa679438eu, 0x49b40821u,
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0xf61e2562u, 0xc040b340u, 0x265e5a51u, 0xe9b6c7aau,
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0xd62f105du, 0x02441453u, 0xd8a1e681u, 0xe7d3fbc8u,
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0x21e1cde6u, 0xc33707d6u, 0xf4d50d87u, 0x455a14edu,
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0xa9e3e905u, 0xfcefa3f8u, 0x676f02d9u, 0x8d2a4c8au,
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0xfffa3942u, 0x8771f681u, 0x6d9d6122u, 0xfde5380cu,
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0xa4beea44u, 0x4bdecfa9u, 0xf6bb4b60u, 0xbebfbc70u,
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0x289b7ec6u, 0xeaa127fau, 0xd4ef3085u, 0x04881d05u,
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0xd9d4d039u, 0xe6db99e5u, 0x1fa27cf8u, 0xc4ac5665u,
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0xf4292244u, 0x432aff97u, 0xab9423a7u, 0xfc93a039u,
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0x655b59c3u, 0x8f0ccc92u, 0xffeff47du, 0x85845dd1u,
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0x6fa87e4fu, 0xfe2ce6e0u, 0xa3014314u, 0x4e0811a1u,
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0xf7537e82u, 0xbd3af235u, 0x2ad7d2bbu, 0xeb86d391u,
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};
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constexpr std::uint32_t S[16] =
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{
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7, 12, 17, 22,
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5, 9, 14, 20,
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4, 11, 16, 23,
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6, 10, 15, 21
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};
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constexpr char PADDING[64] =
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{
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-128, 0, 0, 0, 0, 0, 0, 0,
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0, 0, 0, 0, 0, 0, 0, 0,
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0, 0, 0, 0, 0, 0, 0, 0,
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0, 0, 0, 0, 0, 0, 0, 0,
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0, 0, 0, 0, 0, 0, 0, 0,
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0, 0, 0, 0, 0, 0, 0, 0,
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0, 0, 0, 0, 0, 0, 0, 0,
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0, 0, 0, 0, 0, 0, 0, 0
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};
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constexpr std::uint32_t rotate(std::uint32_t x, std::uint32_t n)
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{
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return (x << n) | (x >> (32 - n));
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}
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template <typename F>
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constexpr std::uint32_t t(F f, std::uint32_t a, std::uint32_t b, std::uint32_t c, std::uint32_t d, std::uint32_t x, std::uint32_t s, std::uint32_t ac)
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{
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return b + rotate(a + f(b, c, d) + x + ac, s);
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}
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constexpr uint32_t to_uint32(unsigned char const * data)
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{
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return 0
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| (static_cast<uint32_t>(data[1]) << 8)
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| (static_cast<uint32_t>(data[2]) << 16)
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| (static_cast<uint32_t>(data[3]) << 24)
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;
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}
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struct hasher
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{
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std::uint8_t buffer[64];
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std::uint32_t state[4] = { 0x67452301u, 0xefcdab89u, 0x98badcfeu, 0x10325476u };
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std::uint32_t nl = 0;
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std::uint32_t nh = 0;
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constexpr void append(std::string_view data)
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{
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std::uint32_t input[16];
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std::uint32_t k = (nl >> 3) & 0x3f;
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std::uint32_t length = data.size();
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nl += length << 3;
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if (nl < length << 3)
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nh += 1;
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nh += length >> 29;
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for (char c : data)
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{
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buffer[k++] = static_cast<unsigned char>(static_cast<int16_t>(c) + 256);
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if (k == 0x40)
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{
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for (int i = 0; i < 16; ++i)
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input[i] = to_uint32(buffer + i * 4);
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transform(input);
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k = 0;
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}
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}
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}
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constexpr void transform(std::uint32_t const (&input)[16])
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{
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std::uint32_t a = state[0], b = state[1], c = state[2], d = state[3];
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for (uint32_t r = 0; r < 4; ++r)
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{
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const auto g = G + r * 16;
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const auto s = S + r * 4;
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const auto k = K + r * 16;
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for (std::uint32_t i = 0; i < 16; ++i)
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{
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const auto new_b = t(F[r], a, b, c, d, input[g[i]], s[i % 4], k[i]);
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a = d;
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d = c;
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c = b;
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b = new_b;
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}
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}
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state[0] += a;
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state[1] += b;
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state[2] += c;
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state[3] += d;
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}
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constexpr std::array<std::uint32_t, 4> result()
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{
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std::uint32_t input[16];
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const auto k = ((nl >> 3) & 0x3f);
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input[14] = nl;
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input[15] = nh;
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append(std::string_view(PADDING, k < 56 ? 56 - k : 120 - k));
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for (int i = 0; i < 14; ++i) {
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input[i] = to_uint32(buffer + i * 4);
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}
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transform(input);
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return {state[0], state[1], state[2], state[3]};
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}
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};
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}
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namespace md5_inl
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{
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using hasher = md5_detail::hasher;
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constexpr auto hash(std::string_view data)
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{
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hasher h;
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h.append(data);
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return h.result();
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}
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}
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}
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12
libs/util/source/md5.cpp
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12
libs/util/source/md5.cpp
Normal file
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@ -0,0 +1,12 @@
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#include <psemek/util/md5.hpp>
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#include <psemek/util/md5_inl.hpp>
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namespace psemek::util
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{
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std::array<std::uint32_t, 4> md5_hash(std::string_view data)
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{
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return md5_inl::hash(data);
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}
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}
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