Commit 90e921f7a7

@@ -28,6 +28,11 @@ const hashes = [_]Hash{
         .name = "wyhash",
         .init_u64 = 0,
     },
+    Hash{
+        .ty = hash.WyhashStateless,
+        .name = "wyhash-stateless",
+        .init_u64 = 0,
+    },
     Hash{
         .ty = hash.SipHash64(1, 3),
         .name = "siphash(1,3)",

@@ -31,13 +31,20 @@ fn mix1(a: u64, b: u64, seed: u64) u64 {
     return mum(a ^ seed ^ primes[2], b ^ seed ^ primes[3]);
 }
 
+/// Fast non-cryptographic 64bit hash function.
+/// See https://github.com/wangyi-fudan/wyhash
 pub const Wyhash = struct {
     seed: u64,
+
+    buf: [32]u8,
+    buf_len: usize,
     msg_len: usize,
 
     pub fn init(seed: u64) Wyhash {
         return Wyhash{
             .seed = seed,
+            .buf = undefined,
+            .buf_len = 0,
             .msg_len = 0,
         };
     }
@@ -56,7 +63,110 @@ pub const Wyhash = struct {
         );
     }
 
-    fn partial(self: *Wyhash, b: []const u8) void {
+    pub fn update(self: *Wyhash, b: []const u8) void {
+        var off: usize = 0;
+
+        // Partial from previous.
+        if (self.buf_len != 0 and self.buf_len + b.len > 32) {
+            off += 32 - self.buf_len;
+            mem.copy(u8, self.buf[self.buf_len..], b[0..off]);
+            self.round(self.buf[0..]);
+            self.buf_len = 0;
+        }
+
+        // Full middle blocks.
+        while (off + 32 <= b.len) : (off += 32) {
+            @inlineCall(self.round, b[off .. off + 32]);
+        }
+
+        // Remainder for next pass.
+        mem.copy(u8, self.buf[self.buf_len..], b[off..]);
+        self.buf_len += @intCast(u8, b[off..].len);
+        self.msg_len += b.len;
+    }
+
+    pub fn final(self: *Wyhash) u64 {
+        const seed = self.seed;
+        const rem_len = @intCast(u5, self.buf_len);
+        const rem_key = self.buf[0..self.buf_len];
+
+        self.seed = switch (rem_len) {
+            0 => seed,
+            1 => mix0(read_bytes(1, rem_key), primes[4], seed),
+            2 => mix0(read_bytes(2, rem_key), primes[4], seed),
+            3 => mix0((read_bytes(2, rem_key) << 8) | read_bytes(1, rem_key[2..]), primes[4], seed),
+            4 => mix0(read_bytes(4, rem_key), primes[4], seed),
+            5 => mix0((read_bytes(4, rem_key) << 8) | read_bytes(1, rem_key[4..]), primes[4], seed),
+            6 => mix0((read_bytes(4, rem_key) << 16) | read_bytes(2, rem_key[4..]), primes[4], seed),
+            7 => mix0((read_bytes(4, rem_key) << 24) | (read_bytes(2, rem_key[4..]) << 8) | read_bytes(1, rem_key[6..]), primes[4], seed),
+            8 => mix0(read_8bytes_swapped(rem_key), primes[4], seed),
+            9 => mix0(read_8bytes_swapped(rem_key), read_bytes(1, rem_key[8..]), seed),
+            10 => mix0(read_8bytes_swapped(rem_key), read_bytes(2, rem_key[8..]), seed),
+            11 => mix0(read_8bytes_swapped(rem_key), (read_bytes(2, rem_key[8..]) << 8) | read_bytes(1, rem_key[10..]), seed),
+            12 => mix0(read_8bytes_swapped(rem_key), read_bytes(4, rem_key[8..]), seed),
+            13 => mix0(read_8bytes_swapped(rem_key), (read_bytes(4, rem_key[8..]) << 8) | read_bytes(1, rem_key[12..]), seed),
+            14 => mix0(read_8bytes_swapped(rem_key), (read_bytes(4, rem_key[8..]) << 16) | read_bytes(2, rem_key[12..]), seed),
+            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),
+            16 => mix0(read_8bytes_swapped(rem_key), read_8bytes_swapped(rem_key[8..]), seed),
+            17 => mix0(read_8bytes_swapped(rem_key), read_8bytes_swapped(rem_key[8..]), seed) ^ mix1(read_bytes(1, rem_key[16..]), primes[4], seed),
+            18 => mix0(read_8bytes_swapped(rem_key), read_8bytes_swapped(rem_key[8..]), seed) ^ mix1(read_bytes(2, rem_key[16..]), primes[4], seed),
+            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),
+            20 => mix0(read_8bytes_swapped(rem_key), read_8bytes_swapped(rem_key[8..]), seed) ^ mix1(read_bytes(4, rem_key[16..]), primes[4], seed),
+            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),
+            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),
+            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),
+            24 => mix0(read_8bytes_swapped(rem_key), read_8bytes_swapped(rem_key[8..]), seed) ^ mix1(read_8bytes_swapped(rem_key[16..]), primes[4], seed),
+            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),
+            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),
+            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),
+            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),
+            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),
+            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),
+            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),
+        };
+
+        return mum(self.seed ^ self.msg_len, primes[4]);
+    }
+
+    pub fn hash(seed: u64, input: []const u8) u64 {
+        var c = Wyhash.init(seed);
+        @inlineCall(c.update, input);
+        return @inlineCall(c.final);
+    }
+};
+
+/// Wyhash version where state is not preserved between successive `update`
+/// calls, ie. it will have different results between hashing the data in
+/// one or several steps.
+/// This allows it to be faster.
+pub const WyhashStateless = struct {
+    seed: u64,
+    msg_len: usize,
+
+    const Self = @This();
+
+    pub fn init(seed: u64) Self {
+        return Self{
+            .seed = seed,
+            .msg_len = 0,
+        };
+    }
+
+    fn round(self: *Self, b: []const u8) void {
+        std.debug.assert(b.len == 32);
+
+        self.seed = mix0(
+            read_bytes(8, b[0..]),
+            read_bytes(8, b[8..]),
+            self.seed,
+        ) ^ mix1(
+            read_bytes(8, b[16..]),
+            read_bytes(8, b[24..]),
+            self.seed,
+        );
+    }
+
+    fn partial(self: *Self, b: []const u8) void {
         const rem_key = b;
         const rem_len = b.len;
 
@@ -98,7 +208,7 @@ pub const Wyhash = struct {
         self.seed = seed;
     }
 
-    pub fn update(self: *Wyhash, b: []const u8) void {
+    pub fn update(self: *Self, b: []const u8) void {
         var off: usize = 0;
 
         // Full middle blocks.
@@ -110,19 +220,20 @@ pub const Wyhash = struct {
         self.msg_len += b.len;
     }
 
-    pub fn final(self: *Wyhash) u64 {
+    pub fn final(self: *Self) u64 {
         return mum(self.seed ^ self.msg_len, primes[4]);
     }
 
     pub fn hash(seed: u64, input: []const u8) u64 {
-        var c = Wyhash.init(seed);
+        var c = Self.init(seed);
         @inlineCall(c.update, input);
         return @inlineCall(c.final);
     }
 };
 
+const expectEqual = std.testing.expectEqual;
+
 test "test vectors" {
-    const expectEqual = std.testing.expectEqual;
     const hash = Wyhash.hash;
 
     expectEqual(hash(0, ""), 0x0);
@@ -133,3 +244,38 @@ test "test vectors" {
     expectEqual(hash(5, "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789"), 0x602a1894d3bbfe7f);
     expectEqual(hash(6, "12345678901234567890123456789012345678901234567890123456789012345678901234567890"), 0x829e9c148b75970e);
 }
+
+test "test vectors streaming" {
+    var wh = Wyhash.init(5);
+    for ("ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789") |e| {
+        wh.update(mem.asBytes(&e));
+    }
+    expectEqual(wh.final(), 0x602a1894d3bbfe7f);
+
+    const pattern = "1234567890";
+    const count = 8;
+    const result = 0x829e9c148b75970e;
+    expectEqual(Wyhash.hash(6, pattern ** 8), result);
+
+    wh = Wyhash.init(6);
+    var i: u32 = 0;
+    while (i < count) : (i += 1) {
+        wh.update(pattern);
+    }
+    expectEqual(wh.final(), result);
+}
+
+test "test vectors stateless" {
+    const hash = WyhashStateless.hash;
+
+    expectEqual(hash(0, ""), 0x0);
+    expectEqual(hash(1, "a"), 0xbed235177f41d328);
+    expectEqual(hash(2, "abc"), 0xbe348debe59b27c3);
+    expectEqual(hash(3, "message digest"), 0x37320f657213a290);
+    expectEqual(hash(4, "abcdefghijklmnopqrstuvwxyz"), 0xd0b270e1d8a7019c);
+    expectEqual(hash(5, "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789"), 0x602a1894d3bbfe7f);
+    expectEqual(hash(6, "12345678901234567890123456789012345678901234567890123456789012345678901234567890"), 0x829e9c148b75970e);
+
+    // We don't check for the streaming API having the same results, as it is
+    // not required to.
+}

@@ -29,6 +29,7 @@ pub const CityHash64 = cityhash.CityHash64;
 
 const wyhash = @import("hash/wyhash.zig");
 pub const Wyhash = wyhash.Wyhash;
+pub const WyhashStateless = wyhash.WyhashStateless;
 
 test "hash" {
     _ = @import("hash/adler.zig");