[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]
Re: [ft-devel] different output from 32-bit and 64bit version of gray_re
From: |
Alexei Podtelezhnikov |
Subject: |
Re: [ft-devel] different output from 32-bit and 64bit version of gray_render_scanline |
Date: |
Thu, 6 Jun 2019 10:00:17 -0400 |
> > So, is this a surprise to anyone? Should the two versions behave
> > identically in the absence of overflow or other extreme cases?
>
> The behaviour should be identical, yes. Reason for two code paths is
> velocity.
Yes. The original version involves complex remainder accounting. I
strongly suspect that it breaks down a bit upon entering
gray_render_scanline. That function should be aware of the remainder
above, but it is not. You are welcome to track it down but it is a
tough code to grasp.