SkScalar and skia

[Janez Zemva]

As we all know, skia supports platforms without a FPU. But what if a
platform has a FPU and skia is compiled not to use it? Has anyone made
any benchmarks? And what happens if GPU accelleration is enabled with
the fixed-point scalars?

[bungeman]

This isn't actually true any more, as support for the fixed-point variation of SkScalar is being phased out. While there is no active effort to remove fixed-point SkScalars, they are no longer tested. If Skia is compiled with fixed-point SkScalars (and SK_CAN_USE_FLOAT is set to 0) the FPU would simply not be used. There used to be benchmarks for this when fixed-point was still tested, but there are no recent ones. The GPU device has always been float and never supported fixed-point SkScalars, usually you just get nothing rendered, or everything renders black (if it works at all). It seems unlikely that hardware with a GPU will lack an FPU, though that is possible.

Do you have some special interest in using Skia on hardware which does not have an FPU?

[Janez Zemva]

> Do you have some special interest in using Skia on hardware which does not
> have an FPU?

I was merely interested in performance comparisons. Could fixed-point
outperform floating-point? I guess not and it is mostly irrelevant
today, as you noted.