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-rw-r--r--lib/std/hash/cityhash.zig387
1 files changed, 387 insertions, 0 deletions
diff --git a/lib/std/hash/cityhash.zig b/lib/std/hash/cityhash.zig
new file mode 100644
index 0000000000..43e5b7a385
--- /dev/null
+++ b/lib/std/hash/cityhash.zig
@@ -0,0 +1,387 @@
+const std = @import("std");
+const builtin = @import("builtin");
+
+pub const CityHash32 = struct {
+ const Self = @This();
+
+ // Magic numbers for 32-bit hashing. Copied from Murmur3.
+ const c1: u32 = 0xcc9e2d51;
+ const c2: u32 = 0x1b873593;
+
+ fn fetch32(ptr: [*]const u8) u32 {
+ var v: u32 = undefined;
+ @memcpy(@ptrCast([*]u8, &v), ptr, 4);
+ if (builtin.endian == builtin.Endian.Big)
+ return @byteSwap(u32, v);
+ return v;
+ }
+
+ // A 32-bit to 32-bit integer hash copied from Murmur3.
+ fn fmix(h: u32) u32 {
+ var h1: u32 = h;
+ h1 ^= h1 >> 16;
+ h1 *%= 0x85ebca6b;
+ h1 ^= h1 >> 13;
+ h1 *%= 0xc2b2ae35;
+ h1 ^= h1 >> 16;
+ return h1;
+ }
+
+ // Rotate right helper
+ fn rotr32(x: u32, comptime r: u32) u32 {
+ return (x >> r) | (x << (32 - r));
+ }
+
+ // Helper from Murmur3 for combining two 32-bit values.
+ fn mur(a: u32, h: u32) u32 {
+ var a1: u32 = a;
+ var h1: u32 = h;
+ a1 *%= c1;
+ a1 = rotr32(a1, 17);
+ a1 *%= c2;
+ h1 ^= a1;
+ h1 = rotr32(h1, 19);
+ return h1 *% 5 +% 0xe6546b64;
+ }
+
+ fn hash32Len0To4(str: []const u8) u32 {
+ const len: u32 = @truncate(u32, str.len);
+ var b: u32 = 0;
+ var c: u32 = 9;
+ for (str) |v| {
+ b = b *% c1 +% @bitCast(u32, @intCast(i32, @bitCast(i8, v)));
+ c ^= b;
+ }
+ return fmix(mur(b, mur(len, c)));
+ }
+
+ fn hash32Len5To12(str: []const u8) u32 {
+ var a: u32 = @truncate(u32, str.len);
+ var b: u32 = a *% 5;
+ var c: u32 = 9;
+ const d: u32 = b;
+
+ a +%= fetch32(str.ptr);
+ b +%= fetch32(str.ptr + str.len - 4);
+ c +%= fetch32(str.ptr + ((str.len >> 1) & 4));
+
+ return fmix(mur(c, mur(b, mur(a, d))));
+ }
+
+ fn hash32Len13To24(str: []const u8) u32 {
+ const len: u32 = @truncate(u32, str.len);
+ const a: u32 = fetch32(str.ptr + (str.len >> 1) - 4);
+ const b: u32 = fetch32(str.ptr + 4);
+ const c: u32 = fetch32(str.ptr + str.len - 8);
+ const d: u32 = fetch32(str.ptr + (str.len >> 1));
+ const e: u32 = fetch32(str.ptr);
+ const f: u32 = fetch32(str.ptr + str.len - 4);
+
+ return fmix(mur(f, mur(e, mur(d, mur(c, mur(b, mur(a, len)))))));
+ }
+
+ pub fn hash(str: []const u8) u32 {
+ if (str.len <= 24) {
+ if (str.len <= 4) {
+ return hash32Len0To4(str);
+ } else {
+ if (str.len <= 12)
+ return hash32Len5To12(str);
+ return hash32Len13To24(str);
+ }
+ }
+
+ const len: u32 = @truncate(u32, str.len);
+ var h: u32 = len;
+ var g: u32 = c1 *% len;
+ var f: u32 = g;
+
+ const a0: u32 = rotr32(fetch32(str.ptr + str.len - 4) *% c1, 17) *% c2;
+ const a1: u32 = rotr32(fetch32(str.ptr + str.len - 8) *% c1, 17) *% c2;
+ const a2: u32 = rotr32(fetch32(str.ptr + str.len - 16) *% c1, 17) *% c2;
+ const a3: u32 = rotr32(fetch32(str.ptr + str.len - 12) *% c1, 17) *% c2;
+ const a4: u32 = rotr32(fetch32(str.ptr + str.len - 20) *% c1, 17) *% c2;
+
+ h ^= a0;
+ h = rotr32(h, 19);
+ h = h *% 5 +% 0xe6546b64;
+ h ^= a2;
+ h = rotr32(h, 19);
+ h = h *% 5 +% 0xe6546b64;
+ g ^= a1;
+ g = rotr32(g, 19);
+ g = g *% 5 +% 0xe6546b64;
+ g ^= a3;
+ g = rotr32(g, 19);
+ g = g *% 5 +% 0xe6546b64;
+ f +%= a4;
+ f = rotr32(f, 19);
+ f = f *% 5 +% 0xe6546b64;
+ var iters = (str.len - 1) / 20;
+ var ptr = str.ptr;
+ while (iters != 0) : (iters -= 1) {
+ const b0: u32 = rotr32(fetch32(ptr) *% c1, 17) *% c2;
+ const b1: u32 = fetch32(ptr + 4);
+ const b2: u32 = rotr32(fetch32(ptr + 8) *% c1, 17) *% c2;
+ const b3: u32 = rotr32(fetch32(ptr + 12) *% c1, 17) *% c2;
+ const b4: u32 = fetch32(ptr + 16);
+
+ h ^= b0;
+ h = rotr32(h, 18);
+ h = h *% 5 +% 0xe6546b64;
+ f +%= b1;
+ f = rotr32(f, 19);
+ f = f *% c1;
+ g +%= b2;
+ g = rotr32(g, 18);
+ g = g *% 5 +% 0xe6546b64;
+ h ^= b3 +% b1;
+ h = rotr32(h, 19);
+ h = h *% 5 +% 0xe6546b64;
+ g ^= b4;
+ g = @byteSwap(u32, g) *% 5;
+ h +%= b4 *% 5;
+ h = @byteSwap(u32, h);
+ f +%= b0;
+ const t: u32 = h;
+ h = f;
+ f = g;
+ g = t;
+ ptr += 20;
+ }
+ g = rotr32(g, 11) *% c1;
+ g = rotr32(g, 17) *% c1;
+ f = rotr32(f, 11) *% c1;
+ f = rotr32(f, 17) *% c1;
+ h = rotr32(h +% g, 19);
+ h = h *% 5 +% 0xe6546b64;
+ h = rotr32(h, 17) *% c1;
+ h = rotr32(h +% f, 19);
+ h = h *% 5 +% 0xe6546b64;
+ h = rotr32(h, 17) *% c1;
+ return h;
+ }
+};
+
+pub const CityHash64 = struct {
+ const Self = @This();
+
+ // Some primes between 2^63 and 2^64 for various uses.
+ const k0: u64 = 0xc3a5c85c97cb3127;
+ const k1: u64 = 0xb492b66fbe98f273;
+ const k2: u64 = 0x9ae16a3b2f90404f;
+
+ fn fetch32(ptr: [*]const u8) u32 {
+ var v: u32 = undefined;
+ @memcpy(@ptrCast([*]u8, &v), ptr, 4);
+ if (builtin.endian == builtin.Endian.Big)
+ return @byteSwap(u32, v);
+ return v;
+ }
+
+ fn fetch64(ptr: [*]const u8) u64 {
+ var v: u64 = undefined;
+ @memcpy(@ptrCast([*]u8, &v), ptr, 8);
+ if (builtin.endian == builtin.Endian.Big)
+ return @byteSwap(u64, v);
+ return v;
+ }
+
+ // Rotate right helper
+ fn rotr64(x: u64, comptime r: u64) u64 {
+ return (x >> r) | (x << (64 - r));
+ }
+
+ fn shiftmix(v: u64) u64 {
+ return v ^ (v >> 47);
+ }
+
+ fn hashLen16(u: u64, v: u64) u64 {
+ return @inlineCall(hash128To64, u, v);
+ }
+
+ fn hashLen16Mul(low: u64, high: u64, mul: u64) u64 {
+ var a: u64 = (low ^ high) *% mul;
+ a ^= (a >> 47);
+ var b: u64 = (high ^ a) *% mul;
+ b ^= (b >> 47);
+ b *%= mul;
+ return b;
+ }
+
+ fn hash128To64(low: u64, high: u64) u64 {
+ return @inlineCall(hashLen16Mul, low, high, 0x9ddfea08eb382d69);
+ }
+
+ fn hashLen0To16(str: []const u8) u64 {
+ const len: u64 = u64(str.len);
+ if (len >= 8) {
+ const mul: u64 = k2 +% len *% 2;
+ const a: u64 = fetch64(str.ptr) +% k2;
+ const b: u64 = fetch64(str.ptr + str.len - 8);
+ const c: u64 = rotr64(b, 37) *% mul +% a;
+ const d: u64 = (rotr64(a, 25) +% b) *% mul;
+ return hashLen16Mul(c, d, mul);
+ }
+ if (len >= 4) {
+ const mul: u64 = k2 +% len *% 2;
+ const a: u64 = fetch32(str.ptr);
+ return hashLen16Mul(len +% (a << 3), fetch32(str.ptr + str.len - 4), mul);
+ }
+ if (len > 0) {
+ const a: u8 = str[0];
+ const b: u8 = str[str.len >> 1];
+ const c: u8 = str[str.len - 1];
+ const y: u32 = @intCast(u32, a) +% (@intCast(u32, b) << 8);
+ const z: u32 = @truncate(u32, str.len) +% (@intCast(u32, c) << 2);
+ return shiftmix(@intCast(u64, y) *% k2 ^ @intCast(u64, z) *% k0) *% k2;
+ }
+ return k2;
+ }
+
+ fn hashLen17To32(str: []const u8) u64 {
+ const len: u64 = u64(str.len);
+ const mul: u64 = k2 +% len *% 2;
+ const a: u64 = fetch64(str.ptr) *% k1;
+ const b: u64 = fetch64(str.ptr + 8);
+ const c: u64 = fetch64(str.ptr + str.len - 8) *% mul;
+ const d: u64 = fetch64(str.ptr + str.len - 16) *% k2;
+
+ return hashLen16Mul(rotr64(a +% b, 43) +% rotr64(c, 30) +% d, a +% rotr64(b +% k2, 18) +% c, mul);
+ }
+
+ fn hashLen33To64(str: []const u8) u64 {
+ const len: u64 = u64(str.len);
+ const mul: u64 = k2 +% len *% 2;
+ const a: u64 = fetch64(str.ptr) *% k2;
+ const b: u64 = fetch64(str.ptr + 8);
+ const c: u64 = fetch64(str.ptr + str.len - 24);
+ const d: u64 = fetch64(str.ptr + str.len - 32);
+ const e: u64 = fetch64(str.ptr + 16) *% k2;
+ const f: u64 = fetch64(str.ptr + 24) *% 9;
+ const g: u64 = fetch64(str.ptr + str.len - 8);
+ const h: u64 = fetch64(str.ptr + str.len - 16) *% mul;
+
+ const u: u64 = rotr64(a +% g, 43) +% (rotr64(b, 30) +% c) *% 9;
+ const v: u64 = ((a +% g) ^ d) +% f +% 1;
+ const w: u64 = @byteSwap(u64, (u +% v) *% mul) +% h;
+ const x: u64 = rotr64(e +% f, 42) +% c;
+ const y: u64 = (@byteSwap(u64, (v +% w) *% mul) +% g) *% mul;
+ const z: u64 = e +% f +% c;
+ const a1: u64 = @byteSwap(u64, (x +% z) *% mul +% y) +% b;
+ const b1: u64 = shiftmix((z +% a1) *% mul +% d +% h) *% mul;
+ return b1 +% x;
+ }
+
+ const WeakPair = struct {
+ first: u64,
+ second: u64,
+ };
+
+ fn weakHashLen32WithSeedsHelper(w: u64, x: u64, y: u64, z: u64, a: u64, b: u64) WeakPair {
+ var a1: u64 = a;
+ var b1: u64 = b;
+ a1 +%= w;
+ b1 = rotr64(b1 +% a1 +% z, 21);
+ var c: u64 = a1;
+ a1 +%= x;
+ a1 +%= y;
+ b1 +%= rotr64(a1, 44);
+ return WeakPair{ .first = a1 +% z, .second = b1 +% c };
+ }
+
+ fn weakHashLen32WithSeeds(ptr: [*]const u8, a: u64, b: u64) WeakPair {
+ return @inlineCall(weakHashLen32WithSeedsHelper, fetch64(ptr), fetch64(ptr + 8), fetch64(ptr + 16), fetch64(ptr + 24), a, b);
+ }
+
+ pub fn hash(str: []const u8) u64 {
+ if (str.len <= 32) {
+ if (str.len <= 16) {
+ return hashLen0To16(str);
+ } else {
+ return hashLen17To32(str);
+ }
+ } else if (str.len <= 64) {
+ return hashLen33To64(str);
+ }
+
+ var len: u64 = u64(str.len);
+
+ var x: u64 = fetch64(str.ptr + str.len - 40);
+ var y: u64 = fetch64(str.ptr + str.len - 16) +% fetch64(str.ptr + str.len - 56);
+ var z: u64 = hashLen16(fetch64(str.ptr + str.len - 48) +% len, fetch64(str.ptr + str.len - 24));
+ var v: WeakPair = weakHashLen32WithSeeds(str.ptr + str.len - 64, len, z);
+ var w: WeakPair = weakHashLen32WithSeeds(str.ptr + str.len - 32, y +% k1, x);
+
+ x = x *% k1 +% fetch64(str.ptr);
+ len = (len - 1) & ~@intCast(u64, 63);
+
+ var ptr: [*]const u8 = str.ptr;
+ while (true) {
+ x = rotr64(x +% y +% v.first +% fetch64(ptr + 8), 37) *% k1;
+ y = rotr64(y +% v.second +% fetch64(ptr + 48), 42) *% k1;
+ x ^= w.second;
+ y +%= v.first +% fetch64(ptr + 40);
+ z = rotr64(z +% w.first, 33) *% k1;
+ v = weakHashLen32WithSeeds(ptr, v.second *% k1, x +% w.first);
+ w = weakHashLen32WithSeeds(ptr + 32, z +% w.second, y +% fetch64(ptr + 16));
+ const t: u64 = z;
+ z = x;
+ x = t;
+
+ ptr += 64;
+ len -= 64;
+ if (len == 0)
+ break;
+ }
+
+ return hashLen16(hashLen16(v.first, w.first) +% shiftmix(y) *% k1 +% z, hashLen16(v.second, w.second) +% x);
+ }
+
+ pub fn hashWithSeed(str: []const u8, seed: u64) u64 {
+ return @inlineCall(Self.hashWithSeeds, str, k2, seed);
+ }
+
+ pub fn hashWithSeeds(str: []const u8, seed0: u64, seed1: u64) u64 {
+ return hashLen16(hash(str) -% seed0, seed1);
+ }
+};
+
+fn SMHasherTest(comptime hash_fn: var, comptime hashbits: u32) u32 {
+ const hashbytes = hashbits / 8;
+ var key: [256]u8 = undefined;
+ var hashes: [hashbytes * 256]u8 = undefined;
+ var final: [hashbytes]u8 = undefined;
+
+ @memset(@ptrCast([*]u8, &key[0]), 0, @sizeOf(@typeOf(key)));
+ @memset(@ptrCast([*]u8, &hashes[0]), 0, @sizeOf(@typeOf(hashes)));
+ @memset(@ptrCast([*]u8, &final[0]), 0, @sizeOf(@typeOf(final)));
+
+ var i: u32 = 0;
+ while (i < 256) : (i += 1) {
+ key[i] = @intCast(u8, i);
+
+ var h = hash_fn(key[0..i], 256 - i);
+ if (builtin.endian == builtin.Endian.Big)
+ h = @byteSwap(@typeOf(h), h);
+ @memcpy(@ptrCast([*]u8, &hashes[i * hashbytes]), @ptrCast([*]u8, &h), hashbytes);
+ }
+
+ return @truncate(u32, hash_fn(hashes, 0));
+}
+
+fn CityHash32hashIgnoreSeed(str: []const u8, seed: u32) u32 {
+ return CityHash32.hash(str);
+}
+
+test "cityhash32" {
+ // Note: SMHasher doesn't provide a 32bit version of the algorithm.
+ // Note: The implementation was verified against the Google Abseil version.
+ std.testing.expectEqual(SMHasherTest(CityHash32hashIgnoreSeed, 32), 0x68254F81);
+}
+
+test "cityhash64" {
+ // Note: This is not compliant with the SMHasher implementation of CityHash64!
+ // Note: The implementation was verified against the Google Abseil version.
+ std.testing.expectEqual(SMHasherTest(CityHash64.hashWithSeed, 64), 0x5FABC5C5);
+}
generated by cgit v1.2.3 (git 2.39.1) at 2025-12-27 22:04:37 +0000