mirror of
https://github.com/ziglang/zig.git
synced 2026-01-04 12:33:19 +00:00
Modify cityhash to work at comptime
This commit is contained in:
Martin Wickham
Andrew Kelley
parent
73b17474d7
commit
21213127ec
@ -6,6 +6,19 @@
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const std = @import("std");
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const builtin = @import("builtin");
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inline fn offsetPtr(ptr: [*]const u8, offset: usize) [*]const u8 {
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// ptr + offset doesn't work at comptime so we need this instead.
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return @ptrCast([*]const u8, &ptr[offset]);
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}
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fn fetch32(ptr: [*]const u8, offset: usize) u32 {
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return std.mem.readIntLittle(u32, offsetPtr(ptr, offset)[0..4]);
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}
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fn fetch64(ptr: [*]const u8, offset: usize) u64 {
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return std.mem.readIntLittle(u64, offsetPtr(ptr, offset)[0..8]);
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}
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pub const CityHash32 = struct {
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const Self = @This();
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@ -13,14 +26,6 @@ pub const CityHash32 = struct {
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const c1: u32 = 0xcc9e2d51;
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const c2: u32 = 0x1b873593;
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fn fetch32(ptr: [*]const u8) u32 {
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var v: u32 = undefined;
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@memcpy(@ptrCast([*]u8, &v), ptr, 4);
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if (builtin.endian == .Big)
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return @byteSwap(u32, v);
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return v;
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}
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// A 32-bit to 32-bit integer hash copied from Murmur3.
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fn fmix(h: u32) u32 {
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var h1: u32 = h;
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@ -66,21 +71,21 @@ pub const CityHash32 = struct {
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var c: u32 = 9;
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const d: u32 = b;
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a +%= fetch32(str.ptr);
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b +%= fetch32(str.ptr + str.len - 4);
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c +%= fetch32(str.ptr + ((str.len >> 1) & 4));
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a +%= fetch32(str.ptr, 0);
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b +%= fetch32(str.ptr, str.len - 4);
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c +%= fetch32(str.ptr, (str.len >> 1) & 4);
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return fmix(mur(c, mur(b, mur(a, d))));
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}
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fn hash32Len13To24(str: []const u8) u32 {
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const len: u32 = @truncate(u32, str.len);
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const a: u32 = fetch32(str.ptr + (str.len >> 1) - 4);
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const b: u32 = fetch32(str.ptr + 4);
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const c: u32 = fetch32(str.ptr + str.len - 8);
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const d: u32 = fetch32(str.ptr + (str.len >> 1));
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const e: u32 = fetch32(str.ptr);
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const f: u32 = fetch32(str.ptr + str.len - 4);
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const a: u32 = fetch32(str.ptr, (str.len >> 1) - 4);
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const b: u32 = fetch32(str.ptr, 4);
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const c: u32 = fetch32(str.ptr, str.len - 8);
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const d: u32 = fetch32(str.ptr, str.len >> 1);
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const e: u32 = fetch32(str.ptr, 0);
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const f: u32 = fetch32(str.ptr, str.len - 4);
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return fmix(mur(f, mur(e, mur(d, mur(c, mur(b, mur(a, len)))))));
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}
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@ -101,11 +106,11 @@ pub const CityHash32 = struct {
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var g: u32 = c1 *% len;
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var f: u32 = g;
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const a0: u32 = rotr32(fetch32(str.ptr + str.len - 4) *% c1, 17) *% c2;
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const a1: u32 = rotr32(fetch32(str.ptr + str.len - 8) *% c1, 17) *% c2;
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const a2: u32 = rotr32(fetch32(str.ptr + str.len - 16) *% c1, 17) *% c2;
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const a3: u32 = rotr32(fetch32(str.ptr + str.len - 12) *% c1, 17) *% c2;
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const a4: u32 = rotr32(fetch32(str.ptr + str.len - 20) *% c1, 17) *% c2;
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const a0: u32 = rotr32(fetch32(str.ptr, str.len - 4) *% c1, 17) *% c2;
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const a1: u32 = rotr32(fetch32(str.ptr, str.len - 8) *% c1, 17) *% c2;
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const a2: u32 = rotr32(fetch32(str.ptr, str.len - 16) *% c1, 17) *% c2;
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const a3: u32 = rotr32(fetch32(str.ptr, str.len - 12) *% c1, 17) *% c2;
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const a4: u32 = rotr32(fetch32(str.ptr, str.len - 20) *% c1, 17) *% c2;
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h ^= a0;
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h = rotr32(h, 19);
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@ -125,11 +130,11 @@ pub const CityHash32 = struct {
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var iters = (str.len - 1) / 20;
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var ptr = str.ptr;
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while (iters != 0) : (iters -= 1) {
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const b0: u32 = rotr32(fetch32(ptr) *% c1, 17) *% c2;
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const b1: u32 = fetch32(ptr + 4);
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const b2: u32 = rotr32(fetch32(ptr + 8) *% c1, 17) *% c2;
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const b3: u32 = rotr32(fetch32(ptr + 12) *% c1, 17) *% c2;
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const b4: u32 = fetch32(ptr + 16);
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const b0: u32 = rotr32(fetch32(ptr, 0) *% c1, 17) *% c2;
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const b1: u32 = fetch32(ptr, 4);
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const b2: u32 = rotr32(fetch32(ptr, 8) *% c1, 17) *% c2;
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const b3: u32 = rotr32(fetch32(ptr, 12) *% c1, 17) *% c2;
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const b4: u32 = fetch32(ptr, 16);
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h ^= b0;
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h = rotr32(h, 18);
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@ -152,7 +157,7 @@ pub const CityHash32 = struct {
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h = f;
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f = g;
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g = t;
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ptr += 20;
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ptr = offsetPtr(ptr, 20);
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}
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g = rotr32(g, 11) *% c1;
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g = rotr32(g, 17) *% c1;
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@ -176,22 +181,6 @@ pub const CityHash64 = struct {
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const k1: u64 = 0xb492b66fbe98f273;
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const k2: u64 = 0x9ae16a3b2f90404f;
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fn fetch32(ptr: [*]const u8) u32 {
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var v: u32 = undefined;
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@memcpy(@ptrCast([*]u8, &v), ptr, 4);
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if (builtin.endian == .Big)
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return @byteSwap(u32, v);
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return v;
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}
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fn fetch64(ptr: [*]const u8) u64 {
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var v: u64 = undefined;
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@memcpy(@ptrCast([*]u8, &v), ptr, 8);
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if (builtin.endian == .Big)
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return @byteSwap(u64, v);
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return v;
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}
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// Rotate right helper
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fn rotr64(x: u64, comptime r: u64) u64 {
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return (x >> r) | (x << (64 - r));
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@ -222,16 +211,16 @@ pub const CityHash64 = struct {
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const len: u64 = @as(u64, str.len);
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if (len >= 8) {
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const mul: u64 = k2 +% len *% 2;
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const a: u64 = fetch64(str.ptr) +% k2;
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const b: u64 = fetch64(str.ptr + str.len - 8);
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const a: u64 = fetch64(str.ptr, 0) +% k2;
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const b: u64 = fetch64(str.ptr, str.len - 8);
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const c: u64 = rotr64(b, 37) *% mul +% a;
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const d: u64 = (rotr64(a, 25) +% b) *% mul;
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return hashLen16Mul(c, d, mul);
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}
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if (len >= 4) {
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const mul: u64 = k2 +% len *% 2;
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const a: u64 = fetch32(str.ptr);
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return hashLen16Mul(len +% (a << 3), fetch32(str.ptr + str.len - 4), mul);
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const a: u64 = fetch32(str.ptr, 0);
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return hashLen16Mul(len +% (a << 3), fetch32(str.ptr, str.len - 4), mul);
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}
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if (len > 0) {
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const a: u8 = str[0];
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@ -247,10 +236,10 @@ pub const CityHash64 = struct {
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fn hashLen17To32(str: []const u8) u64 {
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const len: u64 = @as(u64, str.len);
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const mul: u64 = k2 +% len *% 2;
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const a: u64 = fetch64(str.ptr) *% k1;
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const b: u64 = fetch64(str.ptr + 8);
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const c: u64 = fetch64(str.ptr + str.len - 8) *% mul;
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const d: u64 = fetch64(str.ptr + str.len - 16) *% k2;
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const a: u64 = fetch64(str.ptr, 0) *% k1;
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const b: u64 = fetch64(str.ptr, 8);
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const c: u64 = fetch64(str.ptr, str.len - 8) *% mul;
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const d: u64 = fetch64(str.ptr, str.len - 16) *% k2;
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return hashLen16Mul(rotr64(a +% b, 43) +% rotr64(c, 30) +% d, a +% rotr64(b +% k2, 18) +% c, mul);
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}
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@ -258,14 +247,14 @@ pub const CityHash64 = struct {
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fn hashLen33To64(str: []const u8) u64 {
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const len: u64 = @as(u64, str.len);
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const mul: u64 = k2 +% len *% 2;
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const a: u64 = fetch64(str.ptr) *% k2;
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const b: u64 = fetch64(str.ptr + 8);
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const c: u64 = fetch64(str.ptr + str.len - 24);
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const d: u64 = fetch64(str.ptr + str.len - 32);
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const e: u64 = fetch64(str.ptr + 16) *% k2;
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const f: u64 = fetch64(str.ptr + 24) *% 9;
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const g: u64 = fetch64(str.ptr + str.len - 8);
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const h: u64 = fetch64(str.ptr + str.len - 16) *% mul;
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const a: u64 = fetch64(str.ptr, 0) *% k2;
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const b: u64 = fetch64(str.ptr, 8);
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const c: u64 = fetch64(str.ptr, str.len - 24);
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const d: u64 = fetch64(str.ptr, str.len - 32);
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const e: u64 = fetch64(str.ptr, 16) *% k2;
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const f: u64 = fetch64(str.ptr, 24) *% 9;
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const g: u64 = fetch64(str.ptr, str.len - 8);
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const h: u64 = fetch64(str.ptr, str.len - 16) *% mul;
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const u: u64 = rotr64(a +% g, 43) +% (rotr64(b, 30) +% c) *% 9;
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const v: u64 = ((a +% g) ^ d) +% f +% 1;
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@ -297,10 +286,10 @@ pub const CityHash64 = struct {
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fn weakHashLen32WithSeeds(ptr: [*]const u8, a: u64, b: u64) WeakPair {
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return @call(.{ .modifier = .always_inline }, weakHashLen32WithSeedsHelper, .{
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fetch64(ptr),
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fetch64(ptr + 8),
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fetch64(ptr + 16),
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fetch64(ptr + 24),
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fetch64(ptr, 0),
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fetch64(ptr, 8),
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fetch64(ptr, 16),
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fetch64(ptr, 24),
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a,
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b,
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});
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@ -319,29 +308,29 @@ pub const CityHash64 = struct {
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var len: u64 = @as(u64, str.len);
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var x: u64 = fetch64(str.ptr + str.len - 40);
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var y: u64 = fetch64(str.ptr + str.len - 16) +% fetch64(str.ptr + str.len - 56);
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var z: u64 = hashLen16(fetch64(str.ptr + str.len - 48) +% len, fetch64(str.ptr + str.len - 24));
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var v: WeakPair = weakHashLen32WithSeeds(str.ptr + str.len - 64, len, z);
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var w: WeakPair = weakHashLen32WithSeeds(str.ptr + str.len - 32, y +% k1, x);
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var x: u64 = fetch64(str.ptr, str.len - 40);
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var y: u64 = fetch64(str.ptr, str.len - 16) +% fetch64(str.ptr, str.len - 56);
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var z: u64 = hashLen16(fetch64(str.ptr, str.len - 48) +% len, fetch64(str.ptr, str.len - 24));
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var v: WeakPair = weakHashLen32WithSeeds(offsetPtr(str.ptr, str.len - 64), len, z);
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var w: WeakPair = weakHashLen32WithSeeds(offsetPtr(str.ptr, str.len - 32), y +% k1, x);
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x = x *% k1 +% fetch64(str.ptr);
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x = x *% k1 +% fetch64(str.ptr, 0);
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len = (len - 1) & ~@intCast(u64, 63);
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var ptr: [*]const u8 = str.ptr;
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while (true) {
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x = rotr64(x +% y +% v.first +% fetch64(ptr + 8), 37) *% k1;
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y = rotr64(y +% v.second +% fetch64(ptr + 48), 42) *% k1;
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x = rotr64(x +% y +% v.first +% fetch64(ptr, 8), 37) *% k1;
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y = rotr64(y +% v.second +% fetch64(ptr, 48), 42) *% k1;
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x ^= w.second;
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y +%= v.first +% fetch64(ptr + 40);
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y +%= v.first +% fetch64(ptr, 40);
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z = rotr64(z +% w.first, 33) *% k1;
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v = weakHashLen32WithSeeds(ptr, v.second *% k1, x +% w.first);
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w = weakHashLen32WithSeeds(ptr + 32, z +% w.second, y +% fetch64(ptr + 16));
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w = weakHashLen32WithSeeds(offsetPtr(ptr, 32), z +% w.second, y +% fetch64(ptr, 16));
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const t: u64 = z;
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z = x;
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x = t;
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ptr += 64;
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ptr = offsetPtr(ptr, 64);
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len -= 64;
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if (len == 0)
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break;
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@ -359,27 +348,31 @@ pub const CityHash64 = struct {
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}
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};
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fn SMHasherTest(comptime hash_fn: anytype, comptime hashbits: u32) u32 {
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const hashbytes = hashbits / 8;
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var key: [256]u8 = undefined;
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var hashes: [hashbytes * 256]u8 = undefined;
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var final: [hashbytes]u8 = undefined;
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fn SMHasherTest(comptime hash_fn: anytype) u32 {
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const HashResult = @typeInfo(@TypeOf(hash_fn)).Fn.return_type.?;
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@memset(@ptrCast([*]u8, &key[0]), 0, @sizeOf(@TypeOf(key)));
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@memset(@ptrCast([*]u8, &hashes[0]), 0, @sizeOf(@TypeOf(hashes)));
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@memset(@ptrCast([*]u8, &final[0]), 0, @sizeOf(@TypeOf(final)));
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var key: [256]u8 = undefined;
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var hashes_bytes: [256 * @sizeOf(HashResult)]u8 = undefined;
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var final: HashResult = 0;
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std.mem.set(u8, &key, 0);
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std.mem.set(u8, &hashes_bytes, 0);
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var i: u32 = 0;
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while (i < 256) : (i += 1) {
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key[i] = @intCast(u8, i);
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var h = hash_fn(key[0..i], 256 - i);
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if (builtin.endian == .Big)
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h = @byteSwap(@TypeOf(h), h);
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@memcpy(@ptrCast([*]u8, &hashes[i * hashbytes]), @ptrCast([*]u8, &h), hashbytes);
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var h: HashResult = hash_fn(key[0..i], 256 - i);
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// comptime can't really do reinterpret casting yet,
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// so we need to write the bytes manually.
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for (hashes_bytes[i*@sizeOf(HashResult)..][0..@sizeOf(HashResult)]) |*byte| {
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byte.* = @truncate(u8, h);
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h = h >> 8;
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}
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}
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return @truncate(u32, hash_fn(&hashes, 0));
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return @truncate(u32, hash_fn(&hashes_bytes, 0));
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}
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fn CityHash32hashIgnoreSeed(str: []const u8, seed: u32) u32 {
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@ -387,13 +380,28 @@ fn CityHash32hashIgnoreSeed(str: []const u8, seed: u32) u32 {
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}
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test "cityhash32" {
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// Note: SMHasher doesn't provide a 32bit version of the algorithm.
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// Note: The implementation was verified against the Google Abseil version.
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std.testing.expectEqual(SMHasherTest(CityHash32hashIgnoreSeed, 32), 0x68254F81);
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const Test = struct {
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fn doTest() void {
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// Note: SMHasher doesn't provide a 32bit version of the algorithm.
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// Note: The implementation was verified against the Google Abseil version.
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std.testing.expectEqual(SMHasherTest(CityHash32hashIgnoreSeed), 0x68254F81);
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std.testing.expectEqual(SMHasherTest(CityHash32hashIgnoreSeed), 0x68254F81);
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}
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};
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Test.doTest();
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@setEvalBranchQuota(50000);
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comptime Test.doTest();
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}
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test "cityhash64" {
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// Note: This is not compliant with the SMHasher implementation of CityHash64!
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// Note: The implementation was verified against the Google Abseil version.
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std.testing.expectEqual(SMHasherTest(CityHash64.hashWithSeed, 64), 0x5FABC5C5);
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const Test = struct {
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fn doTest() void {
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// Note: This is not compliant with the SMHasher implementation of CityHash64!
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// Note: The implementation was verified against the Google Abseil version.
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std.testing.expectEqual(SMHasherTest(CityHash64.hashWithSeed), 0x5FABC5C5);
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}
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};
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Test.doTest();
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@setEvalBranchQuota(50000);
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comptime Test.doTest();
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}
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