Re: [boost] [fixed_point] First presentation from GSoC 2015 and more

Subject: Re: [boost] [fixed_point] First presentation from GSoC 2015 and more
From: Michael Marcin (mike.marcin_at_[hidden])
Date: 2016-10-18 22:41:17

On 10/18/2016 6:51 PM, John McFarlane wrote:
> I can only speak for P0037 although P0106 has also been reviewed by SG14.
> Adding <cmath>-like functions was discussed at our meeting in March. It's
> also briefly discussed in P0037: https://github.com/johnmcfarla
> ne/fixed_point/blob/master/doc/p0037r3.md#library-support
>
> The proposal is quite tightly scoped. However, that doesn't stop me
> prototyping surrounding features in the reference implementation [
> https://github.com/johnmcfarlane/fixed_point/] - especially if I think they
> might warrant standardization at a later date. These functions are quite a
> lot to bite off which is why I only supplied a few wrappers so far. I'm
> sure it's not easy to get better performance that FPU-supported
> floating-point variants. However, I am interested in seeing if I can make
> use of the algorithms in Boost.fixed_point.
>

I'm not sure what the target is. My game dev fixed-point usage falls 
into 4 broad categories:

1. deterministic reproducible game state representation/logic (eg stable 
replay format across multiple platforms/compilers/releases)
2. network/serialization formats
3. converting assets for use with GLES 1.x GPUs
4. embedded/mobile systems with no FPU, no GPU and sometimes no or 
limited software floating-point emulation

Performance was not a major issue for fixed-point outside of the last 
case in which the std floating-point cmath routines were horribly slow 
and/or broken.