Quick way to assign @Vector(4, u8) to [4]u8 or u32?

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1

I currently abuse a union, but I’m wondering if I’m missing something easier.

Thanks.

const PixmapEntryType = extern union {
    u: u32,
    a: [4]u8,
    v: @Vector(4, u8),
};
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2

What about this are you finding difficult?

3

Apparently only the @Vector(4, u8) → u32 assignment requires a bunch of machinery–probably reasonable given that it would depend on endianness.

Interestingly, once I poked at it, an assignment from @Vector(4, u8) to [4]u8 works just fine without any casts.

4 
const std = @import("std");

test "foo" {
    const v: @Vector(4, u8) = @splat(1);
    const a: [4]u8 = v;
    const u_from_v: u32 = @bitCast(v);
    const u_from_a: u32 = @bitCast(a);

    std.debug.assert(u_from_v == u_from_a);
}
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5

Ah, right, @bitCast. That’s what I was looking for.

Thanks.

6

Be careful to not use @bitCast on @Vector’s with integers other than u8,u16,u32,u64. Currently it behaves differently on llvm and x86_64 backends Miscompilation when bitcasting numbers to vector in x86-64 backend · Issue #23851 · ziglang/zig · GitHub

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