Commit 21213127ec
Changed files (1)
lib
std
hash
lib/std/hash/cityhash.zig
@@ -6,6 +6,19 @@
const std = @import("std");
const builtin = @import("builtin");
+inline fn offsetPtr(ptr: [*]const u8, offset: usize) [*]const u8 {
+ // ptr + offset doesn't work at comptime so we need this instead.
+ return @ptrCast([*]const u8, &ptr[offset]);
+}
+
+fn fetch32(ptr: [*]const u8, offset: usize) u32 {
+ return std.mem.readIntLittle(u32, offsetPtr(ptr, offset)[0..4]);
+}
+
+fn fetch64(ptr: [*]const u8, offset: usize) u64 {
+ return std.mem.readIntLittle(u64, offsetPtr(ptr, offset)[0..8]);
+}
+
pub const CityHash32 = struct {
const Self = @This();
@@ -13,14 +26,6 @@ pub const CityHash32 = struct {
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 == .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;
@@ -66,21 +71,21 @@ pub const CityHash32 = struct {
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));
+ a +%= fetch32(str.ptr, 0);
+ 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);
+ 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, 0);
+ const f: u32 = fetch32(str.ptr, str.len - 4);
return fmix(mur(f, mur(e, mur(d, mur(c, mur(b, mur(a, len)))))));
}
@@ -101,11 +106,11 @@ pub const CityHash32 = struct {
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;
+ 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);
@@ -125,11 +130,11 @@ pub const CityHash32 = struct {
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);
+ const b0: u32 = rotr32(fetch32(ptr, 0) *% 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);
@@ -152,7 +157,7 @@ pub const CityHash32 = struct {
h = f;
f = g;
g = t;
- ptr += 20;
+ ptr = offsetPtr(ptr, 20);
}
g = rotr32(g, 11) *% c1;
g = rotr32(g, 17) *% c1;
@@ -176,22 +181,6 @@ pub const CityHash64 = struct {
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 == .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 == .Big)
- return @byteSwap(u64, v);
- return v;
- }
-
// Rotate right helper
fn rotr64(x: u64, comptime r: u64) u64 {
return (x >> r) | (x << (64 - r));
@@ -222,16 +211,16 @@ pub const CityHash64 = struct {
const len: u64 = @as(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 a: u64 = fetch64(str.ptr, 0) +% 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);
+ const a: u64 = fetch32(str.ptr, 0);
+ return hashLen16Mul(len +% (a << 3), fetch32(str.ptr, str.len - 4), mul);
}
if (len > 0) {
const a: u8 = str[0];
@@ -247,10 +236,10 @@ pub const CityHash64 = struct {
fn hashLen17To32(str: []const u8) u64 {
const len: u64 = @as(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;
+ const a: u64 = fetch64(str.ptr, 0) *% 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);
}
@@ -258,14 +247,14 @@ pub const CityHash64 = struct {
fn hashLen33To64(str: []const u8) u64 {
const len: u64 = @as(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 a: u64 = fetch64(str.ptr, 0) *% 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;
@@ -297,10 +286,10 @@ pub const CityHash64 = struct {
fn weakHashLen32WithSeeds(ptr: [*]const u8, a: u64, b: u64) WeakPair {
return @call(.{ .modifier = .always_inline }, weakHashLen32WithSeedsHelper, .{
- fetch64(ptr),
- fetch64(ptr + 8),
- fetch64(ptr + 16),
- fetch64(ptr + 24),
+ fetch64(ptr, 0),
+ fetch64(ptr, 8),
+ fetch64(ptr, 16),
+ fetch64(ptr, 24),
a,
b,
});
@@ -319,29 +308,29 @@ pub const CityHash64 = struct {
var len: u64 = @as(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);
+ 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(offsetPtr(str.ptr, str.len - 64), len, z);
+ var w: WeakPair = weakHashLen32WithSeeds(offsetPtr(str.ptr, str.len - 32), y +% k1, x);
- x = x *% k1 +% fetch64(str.ptr);
+ x = x *% k1 +% fetch64(str.ptr, 0);
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 = 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);
+ 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));
+ w = weakHashLen32WithSeeds(offsetPtr(ptr, 32), z +% w.second, y +% fetch64(ptr, 16));
const t: u64 = z;
z = x;
x = t;
- ptr += 64;
+ ptr = offsetPtr(ptr, 64);
len -= 64;
if (len == 0)
break;
@@ -359,27 +348,31 @@ pub const CityHash64 = struct {
}
};
-fn SMHasherTest(comptime hash_fn: anytype, comptime hashbits: u32) u32 {
- const hashbytes = hashbits / 8;
+fn SMHasherTest(comptime hash_fn: anytype) u32 {
+ const HashResult = @typeInfo(@TypeOf(hash_fn)).Fn.return_type.?;
+
var key: [256]u8 = undefined;
- var hashes: [hashbytes * 256]u8 = undefined;
- var final: [hashbytes]u8 = undefined;
+ var hashes_bytes: [256 * @sizeOf(HashResult)]u8 = undefined;
+ var final: HashResult = 0;
- @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)));
+ std.mem.set(u8, &key, 0);
+ std.mem.set(u8, &hashes_bytes, 0);
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 == .Big)
- h = @byteSwap(@TypeOf(h), h);
- @memcpy(@ptrCast([*]u8, &hashes[i * hashbytes]), @ptrCast([*]u8, &h), hashbytes);
+ var h: HashResult = hash_fn(key[0..i], 256 - i);
+
+ // comptime can't really do reinterpret casting yet,
+ // so we need to write the bytes manually.
+ for (hashes_bytes[i*@sizeOf(HashResult)..][0..@sizeOf(HashResult)]) |*byte| {
+ byte.* = @truncate(u8, h);
+ h = h >> 8;
+ }
}
- return @truncate(u32, hash_fn(&hashes, 0));
+ return @truncate(u32, hash_fn(&hashes_bytes, 0));
}
fn CityHash32hashIgnoreSeed(str: []const u8, seed: u32) u32 {
@@ -387,13 +380,28 @@ fn CityHash32hashIgnoreSeed(str: []const u8, seed: u32) u32 {
}
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);
+ const Test = struct {
+ fn doTest() void {
+ // 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), 0x68254F81);
+ std.testing.expectEqual(SMHasherTest(CityHash32hashIgnoreSeed), 0x68254F81);
+ }
+ };
+ Test.doTest();
+ @setEvalBranchQuota(50000);
+ comptime Test.doTest();
}
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);
+ const Test = struct {
+ fn doTest() void {
+ // 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), 0x5FABC5C5);
+ }
+ };
+ Test.doTest();
+ @setEvalBranchQuota(50000);
+ comptime Test.doTest();
}