Re: [PATCH v2 0/2] MR340: vkd3d-shader/hlsl: Document some possibly obscure HLSL opcodes.

[Henri Verbeet (＠hverbeet)]

> +    /* MOVC(a, b, c) returns c is bitwise zero and b otherwise.

I think you meant "MOVC(a, b, c) returns c if a is bitwise zero and b otherwise." above.

Alternatively:

"MOVC(x, y, z) evaluates to `z' when `x' is bitwise zero and to `y' otherwise."

At the risk of rehashing a discussion we've been over before, this does suggest that "MOVC" is perhaps not the most appropriate name for operation; this sounds like what some other languages might call "if". (I.e., "MOVC(x, y, z)" is essentially "(if x y z)".)

Are both "y" and "z" always evaluated, or is that conditional on "x" as well?
> +     * TERNARY(a, b, c) returns c if a == 0 and b otherwise.
> +     * They differ for floating point numbers, because
> +     * -0.0 == 0.0, but it is not bitwise zero. */

So "TERNARY(a, b, c)" is equivalent to "MOVC(EQUAL(a, 0), b, c)", right?