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const std = @import("std");
const mem = std.mem;
const expectEqual = std.testing.expectEqual;
const rotl = std.math.rotl;
pub const XxHash64 = struct {
acc1: u64,
acc2: u64,
acc3: u64,
acc4: u64,
seed: u64,
buf: [32]u8,
buf_len: usize,
byte_count: usize,
const prime_1 = 0x9E3779B185EBCA87; // 0b1001111000110111011110011011000110000101111010111100101010000111
const prime_2 = 0xC2B2AE3D27D4EB4F; // 0b1100001010110010101011100011110100100111110101001110101101001111
const prime_3 = 0x165667B19E3779F9; // 0b0001011001010110011001111011000110011110001101110111100111111001
const prime_4 = 0x85EBCA77C2B2AE63; // 0b1000010111101011110010100111011111000010101100101010111001100011
const prime_5 = 0x27D4EB2F165667C5; // 0b0010011111010100111010110010111100010110010101100110011111000101
pub fn init(seed: u64) XxHash64 {
return XxHash64{
.seed = seed,
.acc1 = seed +% prime_1 +% prime_2,
.acc2 = seed +% prime_2,
.acc3 = seed,
.acc4 = seed -% prime_1,
.buf = undefined,
.buf_len = 0,
.byte_count = 0,
};
}
pub fn update(self: *XxHash64, input: []const u8) void {
if (input.len < 32 - self.buf_len) {
mem.copy(u8, self.buf[self.buf_len..], input);
self.buf_len += input.len;
return;
}
var i: usize = 0;
if (self.buf_len > 0) {
i = 32 - self.buf_len;
mem.copy(u8, self.buf[self.buf_len..], input[0..i]);
self.processStripe(&self.buf);
self.buf_len = 0;
}
while (i + 32 <= input.len) : (i += 32) {
self.processStripe(input[i..][0..32]);
}
const remaining_bytes = input[i..];
mem.copy(u8, &self.buf, remaining_bytes);
self.buf_len = remaining_bytes.len;
}
inline fn processStripe(self: *XxHash64, buf: *const [32]u8) void {
self.acc1 = round(self.acc1, mem.readIntLittle(u64, buf[0..8]));
self.acc2 = round(self.acc2, mem.readIntLittle(u64, buf[8..16]));
self.acc3 = round(self.acc3, mem.readIntLittle(u64, buf[16..24]));
self.acc4 = round(self.acc4, mem.readIntLittle(u64, buf[24..32]));
self.byte_count += 32;
}
inline fn round(acc: u64, lane: u64) u64 {
const a = acc +% (lane *% prime_2);
const b = rotl(u64, a, 31);
return b *% prime_1;
}
pub fn final(self: *XxHash64) u64 {
var acc: u64 = undefined;
if (self.byte_count < 32) {
acc = self.seed +% prime_5;
} else {
acc = rotl(u64, self.acc1, 1) +% rotl(u64, self.acc2, 7) +%
rotl(u64, self.acc3, 12) +% rotl(u64, self.acc4, 18);
acc = mergeAccumulator(acc, self.acc1);
acc = mergeAccumulator(acc, self.acc2);
acc = mergeAccumulator(acc, self.acc3);
acc = mergeAccumulator(acc, self.acc4);
}
acc = acc +% @as(u64, self.byte_count) +% @as(u64, self.buf_len);
var pos: usize = 0;
while (pos + 8 <= self.buf_len) : (pos += 8) {
const lane = mem.readIntLittle(u64, self.buf[pos..][0..8]);
acc ^= round(0, lane);
acc = rotl(u64, acc, 27) *% prime_1;
acc +%= prime_4;
}
if (pos + 4 <= self.buf_len) {
const lane = @as(u64, mem.readIntLittle(u32, self.buf[pos..][0..4]));
acc ^= lane *% prime_1;
acc = rotl(u64, acc, 23) *% prime_2;
acc +%= prime_3;
pos += 4;
}
while (pos < self.buf_len) : (pos += 1) {
const lane = @as(u64, self.buf[pos]);
acc ^= lane *% prime_5;
acc = rotl(u64, acc, 11) *% prime_1;
}
acc ^= acc >> 33;
acc *%= prime_2;
acc ^= acc >> 29;
acc *%= prime_3;
acc ^= acc >> 32;
return acc;
}
inline fn mergeAccumulator(acc: u64, other: u64) u64 {
const a = acc ^ round(0, other);
const b = a *% prime_1;
return b +% prime_4;
}
pub fn hash(input: []const u8) u64 {
var hasher = XxHash64.init(0);
hasher.update(input);
return hasher.final();
}
};
pub const XxHash32 = struct {
acc1: u32,
acc2: u32,
acc3: u32,
acc4: u32,
seed: u32,
buf: [16]u8,
buf_len: usize,
byte_count: usize,
const prime_1 = 0x9E3779B1; // 0b10011110001101110111100110110001
const prime_2 = 0x85EBCA77; // 0b10000101111010111100101001110111
const prime_3 = 0xC2B2AE3D; // 0b11000010101100101010111000111101
const prime_4 = 0x27D4EB2F; // 0b00100111110101001110101100101111
const prime_5 = 0x165667B1; // 0b00010110010101100110011110110001
pub fn init(seed: u32) XxHash32 {
return XxHash32{
.seed = seed,
.acc1 = seed +% prime_1 +% prime_2,
.acc2 = seed +% prime_2,
.acc3 = seed,
.acc4 = seed -% prime_1,
.buf = undefined,
.buf_len = 0,
.byte_count = 0,
};
}
pub fn update(self: *XxHash32, input: []const u8) void {
if (input.len < 16 - self.buf_len) {
mem.copy(u8, self.buf[self.buf_len..], input);
self.buf_len += input.len;
return;
}
var i: usize = 0;
if (self.buf_len > 0) {
i = 16 - self.buf_len;
mem.copy(u8, self.buf[self.buf_len..], input[0..i]);
self.processStripe(&self.buf);
self.buf_len = 0;
}
while (i + 16 <= input.len) : (i += 16) {
self.processStripe(input[i..][0..16]);
}
const remaining_bytes = input[i..];
mem.copy(u8, &self.buf, remaining_bytes);
self.buf_len = remaining_bytes.len;
}
inline fn processStripe(self: *XxHash32, buf: *const [16]u8) void {
self.acc1 = round(self.acc1, mem.readIntLittle(u32, buf[0..4]));
self.acc2 = round(self.acc2, mem.readIntLittle(u32, buf[4..8]));
self.acc3 = round(self.acc3, mem.readIntLittle(u32, buf[8..12]));
self.acc4 = round(self.acc4, mem.readIntLittle(u32, buf[12..16]));
self.byte_count += 16;
}
inline fn round(acc: u32, lane: u32) u32 {
const a = acc +% (lane *% prime_2);
const b = rotl(u32, a, 13);
return b *% prime_1;
}
pub fn final(self: *XxHash32) u32 {
var acc: u32 = undefined;
if (self.byte_count < 16) {
acc = self.seed +% prime_5;
} else {
acc = rotl(u32, self.acc1, 1) +% rotl(u32, self.acc2, 7) +%
rotl(u32, self.acc3, 12) +% rotl(u32, self.acc4, 18);
}
acc = acc +% @intCast(u32, self.byte_count) +% @intCast(u32, self.buf_len);
var pos: usize = 0;
while (pos + 4 <= self.buf_len) : (pos += 4) {
const lane = mem.readIntLittle(u32, self.buf[pos..][0..4]);
acc +%= lane *% prime_3;
acc = rotl(u32, acc, 17) *% prime_4;
}
while (pos < self.buf_len) : (pos += 1) {
const lane = @as(u32, self.buf[pos]);
acc +%= lane *% prime_5;
acc = rotl(u32, acc, 11) *% prime_1;
}
acc ^= acc >> 15;
acc *%= prime_2;
acc ^= acc >> 13;
acc *%= prime_3;
acc ^= acc >> 16;
return acc;
}
pub fn hash(input: []const u8) u32 {
var hasher = XxHash32.init(0);
hasher.update(input);
return hasher.final();
}
};
test "xxhash64" {
const hash = XxHash64.hash;
try expectEqual(hash(""), 0xef46db3751d8e999);
try expectEqual(hash("a"), 0xd24ec4f1a98c6e5b);
try expectEqual(hash("abc"), 0x44bc2cf5ad770999);
try expectEqual(hash("message digest"), 0x066ed728fceeb3be);
try expectEqual(hash("abcdefghijklmnopqrstuvwxyz"), 0xcfe1f278fa89835c);
try expectEqual(hash("ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789"), 0xaaa46907d3047814);
try expectEqual(hash("12345678901234567890123456789012345678901234567890123456789012345678901234567890"), 0xe04a477f19ee145d);
}
test "xxhash32" {
const hash = XxHash32.hash;
try expectEqual(hash(""), 0x02cc5d05);
try expectEqual(hash("a"), 0x550d7456);
try expectEqual(hash("abc"), 0x32d153ff);
try expectEqual(hash("message digest"), 0x7c948494);
try expectEqual(hash("abcdefghijklmnopqrstuvwxyz"), 0x63a14d5f);
try expectEqual(hash("ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789"), 0x9c285e64);
try expectEqual(hash("12345678901234567890123456789012345678901234567890123456789012345678901234567890"), 0x9c05f475);
}
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