altagos.dev
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add zigzag coding
+38
+37
src/ZigZag.zig
+37
src/ZigZag.zig
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pub fn encode(value: isize) usize {
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if (value < 0) return @as(usize, @intCast(value * -1)) * 2 - 1;
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return @as(usize, @intCast(value)) * 2;
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}
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pub fn decode(value: usize) isize {
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if (value & 1 == 1) return -@as(isize, @intCast(value / 2)) - 1;
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return @as(isize, @intCast(value / 2));
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}
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test "zigzag.encode val = 10" {
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const testing = @import("std").testing;
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const encoded = encode(10);
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try testing.expectEqual(20, encoded);
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}
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test "zigzag.encode val = -42" {
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const testing = @import("std").testing;
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const encoded = encode(-42);
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try testing.expectEqual(83, encoded);
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}
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test "zigzag.decode val = 20" {
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const testing = @import("std").testing;
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const decoded = decode(20);
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try testing.expectEqual(10, decoded);
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}
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test "zigzag.decode val = 83" {
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const testing = @import("std").testing;
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const decoded = decode(83);
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try testing.expectEqual(-42, decoded);
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}