30 lines
1.0 KiB
Zig
30 lines
1.0 KiB
Zig
const std = @import("std");
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// rounds up a u12 to the nearest factor of 4 and returns the difference
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// (padding)
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pub fn roundUp4Padding(comptime T: type, n: T) T {
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return roundUp4(T, n) - n;
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}
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// rounds up a u12 to the nearest factor of 4.
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pub fn roundUp4(comptime T: type, n: T) T {
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return ((n + 3) & ~@as(T, 3));
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}
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const testing = std.testing;
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test "padding" {
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try testing.expectEqual(roundUp4Padding(u12, 0), 0);
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try testing.expectEqual(roundUp4Padding(u12, 1), 3);
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try testing.expectEqual(roundUp4Padding(u12, 2), 2);
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try testing.expectEqual(roundUp4Padding(u12, 3), 1);
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try testing.expectEqual(roundUp4Padding(u12, 4), 0);
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try testing.expectEqual(roundUp4Padding(u12, 40), 0);
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try testing.expectEqual(roundUp4Padding(u12, 41), 3);
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try testing.expectEqual(roundUp4Padding(u12, 42), 2);
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try testing.expectEqual(roundUp4Padding(u12, 43), 1);
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try testing.expectEqual(roundUp4Padding(u12, 44), 0);
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try testing.expectEqual(roundUp4Padding(u12, 4091), 1);
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try testing.expectEqual(roundUp4Padding(u12, 4092), 0);
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}
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