zig/std/hash/fnv.zig
Jimmi Holst Christensen 8139c5a516
New Zig formal grammar (#1685)
Reverted #1628 and changed the grammar+parser of the language to not allow certain expr where types are expected
2018-11-13 05:08:37 -08:00

59 lines
1.7 KiB
Zig

// FNV1a - Fowler-Noll-Vo hash function
//
// FNV1a is a fast, non-cryptographic hash function with fairly good distribution properties.
//
// https://tools.ietf.org/html/draft-eastlake-fnv-14
const std = @import("../index.zig");
const debug = std.debug;
pub const Fnv1a_32 = Fnv1a(u32, 0x01000193, 0x811c9dc5);
pub const Fnv1a_64 = Fnv1a(u64, 0x100000001b3, 0xcbf29ce484222325);
pub const Fnv1a_128 = Fnv1a(u128, 0x1000000000000000000013b, 0x6c62272e07bb014262b821756295c58d);
fn Fnv1a(comptime T: type, comptime prime: T, comptime offset: T) type {
return struct {
const Self = @This();
value: T,
pub fn init() Self {
return Self{ .value = offset };
}
pub fn update(self: *Self, input: []const u8) void {
for (input) |b| {
self.value ^= b;
self.value *%= prime;
}
}
pub fn final(self: *Self) T {
return self.value;
}
pub fn hash(input: []const u8) T {
var c = Self.init();
c.update(input);
return c.final();
}
};
}
test "fnv1a-32" {
debug.assert(Fnv1a_32.hash("") == 0x811c9dc5);
debug.assert(Fnv1a_32.hash("a") == 0xe40c292c);
debug.assert(Fnv1a_32.hash("foobar") == 0xbf9cf968);
}
test "fnv1a-64" {
debug.assert(Fnv1a_64.hash("") == 0xcbf29ce484222325);
debug.assert(Fnv1a_64.hash("a") == 0xaf63dc4c8601ec8c);
debug.assert(Fnv1a_64.hash("foobar") == 0x85944171f73967e8);
}
test "fnv1a-128" {
debug.assert(Fnv1a_128.hash("") == 0x6c62272e07bb014262b821756295c58d);
debug.assert(Fnv1a_128.hash("a") == 0xd228cb696f1a8caf78912b704e4a8964);
}