Hello Andy,
On 2/11/22 11:28, Andy Shevchenko wrote:
> On Fri, Feb 11, 2022 at 10:19:22AM +0100, Javier Martinez Canillas wrote:
>> Pull the per-line conversion logic into a separate helper function.
>>
>> This will allow to do line-by-line conversion in other helpers that
>> convert to a gray8 format.
>
> ...
>
>> +static void drm_fb_xrgb8888_to_gray8_line(u8 *dst, const u32 *src, unsigned int pixels)
>> +{
>> + unsigned int x;
>> +
>> + for (x = 0; x < pixels; x++) {
>> + u8 r = (*src & 0x00ff0000) >> 16;
>> + u8 g = (*src & 0x0000ff00) >> 8;
>> + u8 b = *src & 0x000000ff;
>> +
>> + /* ITU BT.601: Y = 0.299 R + 0.587 G + 0.114 B */
>> + *dst++ = (3 * r + 6 * g + b) / 10;
>> + src++;
>> + }
>
> Can be done as
>
> while (pixels--) {
> ...
> }
>
> or
>
> do {
> ...
> } while (--pixels);
>
I don't see why a while loop would be an improvement here TBH.
In any case, I just pulled the line conversion logic as a separate
function with minimal code changes since doing that should be in a
separate patch.
Feel free to post a patch if you want to change that while loop.
Best regards,
--
Javier Martinez Canillas
Linux Engineering
Red Hat
