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reimplement wyhash v4.1 (#15969)
This commit is contained in:
Marc Tiehuis
GitHub
parent
cb7040154e
commit
00ff653576
2 changed files with 203 additions and 172 deletions
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@ -343,7 +343,7 @@ test "testHash optional" {
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const b: ?u32 = null;
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try testing.expectEqual(testHash(a), testHash(@as(u32, 123)));
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try testing.expect(testHash(a) != testHash(b));
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try testing.expectEqual(testHash(b), 0);
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try testing.expectEqual(testHash(b), 0x409638ee2bde459); // wyhash empty input hash
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}
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test "testHash array" {
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@ -1,209 +1,240 @@
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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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const T = std.meta.Int(.unsigned, 8 * bytes);
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return mem.readIntLittle(T, data[0..bytes]);
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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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// Wyhash version which does not store internal state for handling partial buffers.
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// This is needed so that we can maximize the speed for the short key case, which will
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// use the non-iterative api which the public Wyhash exposes.
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const WyhashStateless = struct {
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seed: u64,
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msg_len: usize,
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pub fn init(seed: u64) WyhashStateless {
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return WyhashStateless{
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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: *WyhashStateless, 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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pub fn update(self: *WyhashStateless, b: []const u8) void {
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std.debug.assert(b.len % 32 == 0);
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var off: usize = 0;
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while (off < b.len) : (off += 32) {
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@call(.always_inline, round, .{ self, b[off..][0..32] });
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}
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self.msg_len += b.len;
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}
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pub fn final(self: *WyhashStateless, b: []const u8) u64 {
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std.debug.assert(b.len < 32);
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const seed = self.seed;
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const rem_len = @intCast(u5, b.len);
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const rem_key = b[0..rem_len];
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self.seed = switch (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.msg_len += b.len;
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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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const aligned_len = input.len - (input.len % 32);
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var c = WyhashStateless.init(seed);
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@call(.always_inline, update, .{ &c, input[0..aligned_len] });
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return @call(.always_inline, final, .{ &c, input[aligned_len..] });
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}
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};
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/// Fast non-cryptographic 64bit hash function.
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/// See https://github.com/wangyi-fudan/wyhash
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pub const Wyhash = struct {
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state: WyhashStateless,
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const secret = [_]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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};
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buf: [32]u8,
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a: u64,
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b: u64,
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state: [3]u64,
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total_len: usize,
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buf: [48]u8,
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buf_len: usize,
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pub fn init(seed: u64) Wyhash {
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return Wyhash{
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.state = WyhashStateless.init(seed),
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var self = Wyhash{
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.a = undefined,
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.b = undefined,
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.state = undefined,
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.total_len = 0,
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.buf = undefined,
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.buf_len = 0,
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};
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self.state[0] = seed ^ mix(seed ^ secret[0], secret[1]);
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self.state[1] = self.state[0];
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self.state[2] = self.state[0];
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return self;
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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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// This is subtly different from other hash function update calls. Wyhash requires the last
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// full 48-byte block to be run through final1 if is exactly aligned to 48-bytes.
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pub fn update(self: *Wyhash, input: []const u8) void {
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self.total_len += input.len;
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if (self.buf_len != 0 and self.buf_len + b.len >= 32) {
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off += 32 - self.buf_len;
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@memcpy(self.buf[self.buf_len..][0..off], b[0..off]);
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self.state.update(self.buf[0..]);
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if (input.len <= 48 - self.buf_len) {
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@memcpy(self.buf[self.buf_len..][0..input.len], input);
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self.buf_len += input.len;
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return;
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}
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var i: usize = 0;
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if (self.buf_len > 0) {
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i = 48 - self.buf_len;
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@memcpy(self.buf[self.buf_len..][0..i], input[0..i]);
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self.round(&self.buf);
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self.buf_len = 0;
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}
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const remain_len = b.len - off;
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const aligned_len = remain_len - (remain_len % 32);
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self.state.update(b[off .. off + aligned_len]);
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while (i + 48 < input.len) : (i += 48) {
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self.round(input[i..][0..48]);
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}
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const src = b[off + aligned_len ..];
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@memcpy(self.buf[self.buf_len..][0..src.len], src);
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self.buf_len += @intCast(u8, b[off + aligned_len ..].len);
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const remaining_bytes = input[i..];
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@memcpy(self.buf[0..remaining_bytes.len], remaining_bytes);
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self.buf_len = remaining_bytes.len;
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}
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pub fn final(self: *Wyhash) u64 {
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const rem_key = self.buf[0..self.buf_len];
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var input = self.buf[0..self.buf_len];
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var newSelf = self.shallowCopy(); // ensure idempotency
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return self.state.final(rem_key);
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if (self.total_len <= 16) {
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newSelf.smallKey(input);
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} else {
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if (self.buf_len < 16) {
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var scratch: [16]u8 = undefined;
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const rem = 16 - self.buf_len;
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@memcpy(scratch[0..rem], self.buf[self.buf.len - rem ..][0..rem]);
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@memcpy(scratch[rem..][0..self.buf_len], self.buf[0..self.buf_len]);
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// Same as input with lookbehind to pad to 16-bytes
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input = scratch[rem..];
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}
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newSelf.final0();
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newSelf.final1(input);
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}
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return newSelf.final2();
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}
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// Copies the core wyhash state but not any internal buffers.
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inline fn shallowCopy(self: *Wyhash) Wyhash {
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return .{
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.a = self.a,
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.b = self.b,
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.state = self.state,
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.total_len = self.total_len,
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.buf = undefined,
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.buf_len = undefined,
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};
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}
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inline fn smallKey(self: *Wyhash, input: []const u8) void {
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std.debug.assert(input.len <= 16);
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if (input.len >= 4) {
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const end = input.len - 4;
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const quarter = (input.len >> 3) << 2;
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self.a = (read(4, input[0..]) << 32) | read(4, input[quarter..]);
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self.b = (read(4, input[end..]) << 32) | read(4, input[end - quarter ..]);
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} else if (input.len > 0) {
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self.a = (@as(u64, input[0]) << 16) | (@as(u64, input[input.len >> 1]) << 8) | input[input.len - 1];
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self.b = 0;
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} else {
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self.a = 0;
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self.b = 0;
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}
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}
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inline fn round(self: *Wyhash, input: *const [48]u8) void {
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inline for (0..3) |i| {
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const a = read(8, input[8 * (2 * i) ..]);
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const b = read(8, input[8 * (2 * i + 1) ..]);
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self.state[i] = mix(a ^ secret[i + 1], b ^ self.state[i]);
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}
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}
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inline fn read(comptime bytes: usize, data: []const u8) u64 {
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std.debug.assert(bytes <= 8);
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const T = std.meta.Int(.unsigned, 8 * bytes);
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return @as(u64, std.mem.readIntLittle(T, data[0..bytes]));
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}
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inline fn mum(a: *u64, b: *u64) void {
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const x = @as(u128, a.*) *% b.*;
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a.* = @truncate(u64, x);
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b.* = @truncate(u64, x >> 64);
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}
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inline fn mix(a_: u64, b_: u64) u64 {
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var a = a_;
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var b = b_;
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mum(&a, &b);
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return a ^ b;
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}
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inline fn final0(self: *Wyhash) void {
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self.state[0] ^= self.state[1] ^ self.state[2];
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}
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// Input must reside in a 16-byte buffer. The input slice passed be offset into it in which
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// case this function will index in front of the slice.
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inline fn final1(self: *Wyhash, input: []const u8) void {
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std.debug.assert(input.len <= 48);
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var i: usize = 0;
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while (i + 16 < input.len) : (i += 16) {
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self.state[0] = mix(read(8, input[i..]) ^ secret[1], read(8, input[i + 8 ..]) ^ self.state[0]);
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}
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// Possible lookbehind past pointer start.
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self.a = read(8, (input.ptr + input.len - 16)[0..8]);
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self.b = read(8, (input.ptr + input.len - 8)[0..8]);
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}
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inline fn final2(self: *Wyhash) u64 {
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self.a ^= secret[1];
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self.b ^= self.state[0];
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mum(&self.a, &self.b);
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return mix(self.a ^ secret[0] ^ self.total_len, self.b ^ secret[1]);
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}
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pub fn hash(seed: u64, input: []const u8) u64 {
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return WyhashStateless.hash(seed, input);
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var self = Wyhash.init(seed);
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if (input.len <= 16) {
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self.smallKey(input);
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} else {
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var i: usize = 0;
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if (input.len >= 48) {
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while (i + 48 < input.len) : (i += 48) {
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self.round(input[i..][0..48]);
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}
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self.final0();
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}
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self.final1(input[i..]);
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}
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self.total_len = input.len;
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return self.final2();
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}
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};
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const expectEqual = std.testing.expectEqual;
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test "test vectors" {
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const hash = Wyhash.hash;
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const TestVector = struct {
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expected: u64,
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seed: u64,
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input: []const u8,
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};
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try expectEqual(hash(0, ""), 0x0);
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try expectEqual(hash(1, "a"), 0xbed235177f41d328);
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try expectEqual(hash(2, "abc"), 0xbe348debe59b27c3);
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try expectEqual(hash(3, "message digest"), 0x37320f657213a290);
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try expectEqual(hash(4, "abcdefghijklmnopqrstuvwxyz"), 0xd0b270e1d8a7019c);
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try expectEqual(hash(5, "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789"), 0x602a1894d3bbfe7f);
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try expectEqual(hash(6, "12345678901234567890123456789012345678901234567890123456789012345678901234567890"), 0x829e9c148b75970e);
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// Run https://github.com/wangyi-fudan/wyhash/blob/77e50f267fbc7b8e2d09f2d455219adb70ad4749/test_vector.cpp directly.
|
||||
const vectors = [_]TestVector{
|
||||
.{ .seed = 0, .expected = 0x409638ee2bde459, .input = "" },
|
||||
.{ .seed = 1, .expected = 0xa8412d091b5fe0a9, .input = "a" },
|
||||
.{ .seed = 2, .expected = 0x32dd92e4b2915153, .input = "abc" },
|
||||
.{ .seed = 3, .expected = 0x8619124089a3a16b, .input = "message digest" },
|
||||
.{ .seed = 4, .expected = 0x7a43afb61d7f5f40, .input = "abcdefghijklmnopqrstuvwxyz" },
|
||||
.{ .seed = 5, .expected = 0xff42329b90e50d58, .input = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789" },
|
||||
.{ .seed = 6, .expected = 0xc39cab13b115aad3, .input = "12345678901234567890123456789012345678901234567890123456789012345678901234567890" },
|
||||
};
|
||||
|
||||
test "test vectors" {
|
||||
for (vectors) |e| {
|
||||
try expectEqual(e.expected, Wyhash.hash(e.seed, e.input));
|
||||
}
|
||||
}
|
||||
|
||||
test "test vectors streaming" {
|
||||
var wh = Wyhash.init(5);
|
||||
for ("ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789") |e| {
|
||||
wh.update(mem.asBytes(&e));
|
||||
}
|
||||
try expectEqual(wh.final(), 0x602a1894d3bbfe7f);
|
||||
const step = 5;
|
||||
|
||||
const pattern = "1234567890";
|
||||
const count = 8;
|
||||
const result = 0x829e9c148b75970e;
|
||||
try expectEqual(Wyhash.hash(6, pattern ** 8), result);
|
||||
|
||||
wh = Wyhash.init(6);
|
||||
var i: u32 = 0;
|
||||
while (i < count) : (i += 1) {
|
||||
wh.update(pattern);
|
||||
for (vectors) |e| {
|
||||
var wh = Wyhash.init(e.seed);
|
||||
var i: usize = 0;
|
||||
while (i < e.input.len) : (i += step) {
|
||||
const len = if (i + step > e.input.len) e.input.len - i else step;
|
||||
wh.update(e.input[i..][0..len]);
|
||||
}
|
||||
try expectEqual(e.expected, wh.final());
|
||||
}
|
||||
}
|
||||
|
||||
test "test ensure idempotent final call" {
|
||||
const e: TestVector = .{ .seed = 6, .expected = 0xc39cab13b115aad3, .input = "12345678901234567890123456789012345678901234567890123456789012345678901234567890" };
|
||||
var wh = Wyhash.init(e.seed);
|
||||
wh.update(e.input);
|
||||
|
||||
for (0..10) |_| {
|
||||
try expectEqual(e.expected, wh.final());
|
||||
}
|
||||
try expectEqual(wh.final(), result);
|
||||
}
|
||||
|
||||
test "iterative non-divisible update" {
|
||||
|
|
|
|||
Loading…
Add table
Reference in a new issue