d29871977f
We already have a LICENSE file that covers the Zig Standard Library. We no longer need to remind everyone that the license is MIT in every single file. Previously this was introduced to clarify the situation for a fork of Zig that made Zig's LICENSE file harder to find, and replaced it with their own license that required annual payments to their company. However that fork now appears to be dead. So there is no need to reinforce the copyright notice in every single file.
59 lines
1.7 KiB
Zig
59 lines
1.7 KiB
Zig
// FNV1a - Fowler-Noll-Vo hash function
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//
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// FNV1a is a fast, non-cryptographic hash function with fairly good distribution properties.
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//
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// https://tools.ietf.org/html/draft-eastlake-fnv-14
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const std = @import("../std.zig");
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const testing = std.testing;
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pub const Fnv1a_32 = Fnv1a(u32, 0x01000193, 0x811c9dc5);
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pub const Fnv1a_64 = Fnv1a(u64, 0x100000001b3, 0xcbf29ce484222325);
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pub const Fnv1a_128 = Fnv1a(u128, 0x1000000000000000000013b, 0x6c62272e07bb014262b821756295c58d);
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fn Fnv1a(comptime T: type, comptime prime: T, comptime offset: T) type {
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return struct {
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const Self = @This();
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value: T,
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pub fn init() Self {
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return Self{ .value = offset };
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}
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pub fn update(self: *Self, input: []const u8) void {
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for (input) |b| {
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self.value ^= b;
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self.value *%= prime;
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}
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}
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pub fn final(self: *Self) T {
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return self.value;
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}
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pub fn hash(input: []const u8) T {
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var c = Self.init();
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c.update(input);
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return c.final();
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}
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};
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}
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test "fnv1a-32" {
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try testing.expect(Fnv1a_32.hash("") == 0x811c9dc5);
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try testing.expect(Fnv1a_32.hash("a") == 0xe40c292c);
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try testing.expect(Fnv1a_32.hash("foobar") == 0xbf9cf968);
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}
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test "fnv1a-64" {
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try testing.expect(Fnv1a_64.hash("") == 0xcbf29ce484222325);
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try testing.expect(Fnv1a_64.hash("a") == 0xaf63dc4c8601ec8c);
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try testing.expect(Fnv1a_64.hash("foobar") == 0x85944171f73967e8);
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}
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test "fnv1a-128" {
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try testing.expect(Fnv1a_128.hash("") == 0x6c62272e07bb014262b821756295c58d);
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try testing.expect(Fnv1a_128.hash("a") == 0xd228cb696f1a8caf78912b704e4a8964);
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}
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