Re: Wrong colors on ARAnyM

[Michael Schmitz <schmitzmic@gmail.com>]

Hi Geert,

On 15/02/22 09:50, Michael Schmitz wrote:
>
> Either way, I think we've got operator precedence wrong here. Shift 
> takes precedence over bitwise and / or? With that precedence, what we 
> have in summary is
>
>                 shifter_tt.color_reg[regno] =
>                         (((red & 0xe000) >> 13) | ((red & 0x1000) >> 
> 4)) |
>                         (((green & 0xe000) >> 13) | ((green & 0x1000) 
> >> 8)) |
>                         ((blue & 0xe000) >> 13) | ((blue & 0x1000) >> 
> 12);
>
> Only the blue bits ever entirely seem to end up where they ought to. 
> Testing this hypothesis on ARAnyM (without getting it to boot all the 
> way, for some odd reason likely to do with my current .config) shows 
> that the current code results in the shifter_tt.color_reg entries 
> either 5 or 0x17, 0x113 or 0x117. Adding the missing parentheses 
> results in what I'd expect to see.
>
I can confirm that the bug is gone with additional parentheses to apply 
the shifts (<<8 for red, <<4 for green) to the result of the bit-wise 
or, not just the right-hand portion of it.

Do you want me to prepare a patch, or would you prefer to do it yourself?

Cheers,

     Michael