[PATCH] Move mod calculations to a separate helper

[Linus Torvalds]

On Wed, May 14, 2014 at 8:44 PM, Anton Lundin <glance at acc.umu.se> wrote:
>
> I went a little bit hard on trying to use proper units so this code
> doesn't build on older compilers anymore, but we could go a bit less
> haywire on the types and apply something like this.

The problem wasn't that you used proper types, the problem was that
you used much-too-recent C++ features.

Instead of using a cast initializer in a return statement, use a real
variable. So something like

        return (depth_t) { .mm = po2_limit.mbar * 1000 / get_o2(mix) *
10 - 10000 };

requires compilers to support a cast-initializer (whatever it is
called) in an expression, but

        depth_r depth = { .mm = po2_limit.mbar * 1000 / get_o2(mix) *
10 - 10000 };
        return depth;

will just work with any compiler that supports named initializers. And
for *really* old compilers you could even have done

       depth_t depth;
       depth.mm = ...
       return depth;

but I don't think we need to care about anything that predates named
structure initializers (we use them elsewhere already).

The "(type) { .. }" syntax is special and while denser, not really
universally supported as you found out (as usual supported by random
pre-standard compiler versions)

                Linus