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altagos.dev
1pub fn encode(value: isize) usize {
2 if (value < 0) return @as(usize, @intCast(value * -1)) * 2 - 1;
3 return @as(usize, @intCast(value)) * 2;
4}
5
6pub fn decode(value: usize) isize {
7 if (value & 1 == 1) return -@as(isize, @intCast(value / 2)) - 1;
8 return @as(isize, @intCast(value / 2));
9}
10
11test "zigzag.encode val = 10" {
12 const testing = @import("std").testing;
13
14 const encoded = encode(10);
15 try testing.expectEqual(20, encoded);
16}
17
18test "zigzag.encode val = -42" {
19 const testing = @import("std").testing;
20
21 const encoded = encode(-42);
22 try testing.expectEqual(83, encoded);
23}
24
25test "zigzag.decode val = 20" {
26 const testing = @import("std").testing;
27
28 const decoded = decode(20);
29 try testing.expectEqual(10, decoded);
30}
31
32test "zigzag.decode val = 83" {
33 const testing = @import("std").testing;
34
35 const decoded = decode(83);
36 try testing.expectEqual(-42, decoded);
37}