136 lines
7.0 KiB
Zig
136 lines
7.0 KiB
Zig
const std = @import("std");
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const mem = std.mem;
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const primes = [_]u64{
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0xa0761d6478bd642f,
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0xe7037ed1a0b428db,
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0x8ebc6af09c88c6e3,
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0x589965cc75374cc3,
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0x1d8e4e27c47d124f,
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};
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fn read_bytes(comptime bytes: u8, data: []const u8) u64 {
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return mem.readVarInt(u64, data[0..bytes], .Little);
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}
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fn read_8bytes_swapped(data: []const u8) u64 {
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return (read_bytes(4, data) << 32 | read_bytes(4, data[4..]));
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}
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fn mum(a: u64, b: u64) u64 {
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var r = std.math.mulWide(u64, a, b);
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r = (r >> 64) ^ r;
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return @truncate(u64, r);
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}
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fn mix0(a: u64, b: u64, seed: u64) u64 {
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return mum(a ^ seed ^ primes[0], b ^ seed ^ primes[1]);
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}
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fn mix1(a: u64, b: u64, seed: u64) u64 {
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return mum(a ^ seed ^ primes[2], b ^ seed ^ primes[3]);
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}
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pub const Wyhash = struct {
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seed: u64,
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msg_len: usize,
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pub fn init(seed: u64) Wyhash {
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return Wyhash{
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.seed = seed,
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.msg_len = 0,
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};
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}
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fn round(self: *Wyhash, b: []const u8) void {
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std.debug.assert(b.len == 32);
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self.seed = mix0(
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read_bytes(8, b[0..]),
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read_bytes(8, b[8..]),
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self.seed,
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) ^ mix1(
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read_bytes(8, b[16..]),
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read_bytes(8, b[24..]),
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self.seed,
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);
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}
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fn partial(self: *Wyhash, b: []const u8) void {
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const rem_key = b;
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const rem_len = b.len;
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var seed = self.seed;
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seed = switch (@intCast(u5, rem_len)) {
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0 => seed,
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1 => mix0(read_bytes(1, rem_key), primes[4], seed),
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2 => mix0(read_bytes(2, rem_key), primes[4], seed),
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3 => mix0((read_bytes(2, rem_key) << 8) | read_bytes(1, rem_key[2..]), primes[4], seed),
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4 => mix0(read_bytes(4, rem_key), primes[4], seed),
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5 => mix0((read_bytes(4, rem_key) << 8) | read_bytes(1, rem_key[4..]), primes[4], seed),
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6 => mix0((read_bytes(4, rem_key) << 16) | read_bytes(2, rem_key[4..]), primes[4], seed),
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7 => mix0((read_bytes(4, rem_key) << 24) | (read_bytes(2, rem_key[4..]) << 8) | read_bytes(1, rem_key[6..]), primes[4], seed),
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8 => mix0(read_8bytes_swapped(rem_key), primes[4], seed),
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9 => mix0(read_8bytes_swapped(rem_key), read_bytes(1, rem_key[8..]), seed),
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10 => mix0(read_8bytes_swapped(rem_key), read_bytes(2, rem_key[8..]), seed),
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11 => mix0(read_8bytes_swapped(rem_key), (read_bytes(2, rem_key[8..]) << 8) | read_bytes(1, rem_key[10..]), seed),
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12 => mix0(read_8bytes_swapped(rem_key), read_bytes(4, rem_key[8..]), seed),
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13 => mix0(read_8bytes_swapped(rem_key), (read_bytes(4, rem_key[8..]) << 8) | read_bytes(1, rem_key[12..]), seed),
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14 => mix0(read_8bytes_swapped(rem_key), (read_bytes(4, rem_key[8..]) << 16) | read_bytes(2, rem_key[12..]), seed),
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15 => mix0(read_8bytes_swapped(rem_key), (read_bytes(4, rem_key[8..]) << 24) | (read_bytes(2, rem_key[12..]) << 8) | read_bytes(1, rem_key[14..]), seed),
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16 => mix0(read_8bytes_swapped(rem_key), read_8bytes_swapped(rem_key[8..]), seed),
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17 => mix0(read_8bytes_swapped(rem_key), read_8bytes_swapped(rem_key[8..]), seed) ^ mix1(read_bytes(1, rem_key[16..]), primes[4], seed),
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18 => mix0(read_8bytes_swapped(rem_key), read_8bytes_swapped(rem_key[8..]), seed) ^ mix1(read_bytes(2, rem_key[16..]), primes[4], seed),
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19 => mix0(read_8bytes_swapped(rem_key), read_8bytes_swapped(rem_key[8..]), seed) ^ mix1((read_bytes(2, rem_key[16..]) << 8) | read_bytes(1, rem_key[18..]), primes[4], seed),
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20 => mix0(read_8bytes_swapped(rem_key), read_8bytes_swapped(rem_key[8..]), seed) ^ mix1(read_bytes(4, rem_key[16..]), primes[4], seed),
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21 => mix0(read_8bytes_swapped(rem_key), read_8bytes_swapped(rem_key[8..]), seed) ^ mix1((read_bytes(4, rem_key[16..]) << 8) | read_bytes(1, rem_key[20..]), primes[4], seed),
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22 => mix0(read_8bytes_swapped(rem_key), read_8bytes_swapped(rem_key[8..]), seed) ^ mix1((read_bytes(4, rem_key[16..]) << 16) | read_bytes(2, rem_key[20..]), primes[4], seed),
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23 => mix0(read_8bytes_swapped(rem_key), read_8bytes_swapped(rem_key[8..]), seed) ^ mix1((read_bytes(4, rem_key[16..]) << 24) | (read_bytes(2, rem_key[20..]) << 8) | read_bytes(1, rem_key[22..]), primes[4], seed),
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24 => mix0(read_8bytes_swapped(rem_key), read_8bytes_swapped(rem_key[8..]), seed) ^ mix1(read_8bytes_swapped(rem_key[16..]), primes[4], seed),
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25 => mix0(read_8bytes_swapped(rem_key), read_8bytes_swapped(rem_key[8..]), seed) ^ mix1(read_8bytes_swapped(rem_key[16..]), read_bytes(1, rem_key[24..]), seed),
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26 => mix0(read_8bytes_swapped(rem_key), read_8bytes_swapped(rem_key[8..]), seed) ^ mix1(read_8bytes_swapped(rem_key[16..]), read_bytes(2, rem_key[24..]), seed),
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27 => mix0(read_8bytes_swapped(rem_key), read_8bytes_swapped(rem_key[8..]), seed) ^ mix1(read_8bytes_swapped(rem_key[16..]), (read_bytes(2, rem_key[24..]) << 8) | read_bytes(1, rem_key[26..]), seed),
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28 => mix0(read_8bytes_swapped(rem_key), read_8bytes_swapped(rem_key[8..]), seed) ^ mix1(read_8bytes_swapped(rem_key[16..]), read_bytes(4, rem_key[24..]), seed),
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29 => mix0(read_8bytes_swapped(rem_key), read_8bytes_swapped(rem_key[8..]), seed) ^ mix1(read_8bytes_swapped(rem_key[16..]), (read_bytes(4, rem_key[24..]) << 8) | read_bytes(1, rem_key[28..]), seed),
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30 => mix0(read_8bytes_swapped(rem_key), read_8bytes_swapped(rem_key[8..]), seed) ^ mix1(read_8bytes_swapped(rem_key[16..]), (read_bytes(4, rem_key[24..]) << 16) | read_bytes(2, rem_key[28..]), seed),
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31 => mix0(read_8bytes_swapped(rem_key), read_8bytes_swapped(rem_key[8..]), seed) ^ mix1(read_8bytes_swapped(rem_key[16..]), (read_bytes(4, rem_key[24..]) << 24) | (read_bytes(2, rem_key[28..]) << 8) | read_bytes(1, rem_key[30..]), seed),
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};
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self.seed = seed;
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}
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pub fn update(self: *Wyhash, b: []const u8) void {
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var off: usize = 0;
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// Full middle blocks.
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while (off + 32 <= b.len) : (off += 32) {
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@inlineCall(self.round, b[off .. off + 32]);
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}
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self.partial(b[off..]);
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self.msg_len += b.len;
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}
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pub fn final(self: *Wyhash) u64 {
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return mum(self.seed ^ self.msg_len, primes[4]);
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}
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pub fn hash(seed: u64, input: []const u8) u64 {
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var c = Wyhash.init(seed);
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c.update(input);
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return c.final();
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}
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};
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test "test vectors" {
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const expectEqual = std.testing.expectEqual;
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const hash = Wyhash.hash;
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expectEqual(hash(0, ""), 0x0);
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expectEqual(hash(1, "a"), 0xbed235177f41d328);
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expectEqual(hash(2, "abc"), 0xbe348debe59b27c3);
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expectEqual(hash(3, "message digest"), 0x37320f657213a290);
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expectEqual(hash(4, "abcdefghijklmnopqrstuvwxyz"), 0xd0b270e1d8a7019c);
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expectEqual(hash(5, "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789"), 0x602a1894d3bbfe7f);
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expectEqual(hash(6, "12345678901234567890123456789012345678901234567890123456789012345678901234567890"), 0x829e9c148b75970e);
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}
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