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loader: comment on rgb_to_color_index()

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Add small comment block about rgb_to_color_index().
This commit is contained in:
Toomas Soome 2021-01-13 18:38:08 +02:00
parent 52e3a7300d
commit 4bbfe4bf08
1 changed files with 9 additions and 1 deletions
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10
stand/common/gfx_fb.c
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@ -303,7 +303,13 @@ gfx_fb_color_map(uint8_t index)
return (rgb_color_map(index, rmask, 16, gmask, 8, bmask, 0));
}
/* Get indexed color */
/*
* Get indexed color from RGB. This function is used to write data to video
* memory when the adapter is set to use indexed colors.
* Since UEFI does only support 32-bit colors, we do not implement it for
* UEFI because there is no need for it and we do not have palette array
* for UEFI.
*/
static uint8_t
rgb_to_color_index(uint8_t r, uint8_t g, uint8_t b)
{
@ -321,8 +327,10 @@ rgb_to_color_index(uint8_t r, uint8_t g, uint8_t b)
diff = b - pe8[k].Blue;
dist += diff * diff;
/* Exact match, exit the loop */
if (dist == 0)
break;
if (dist < best) {
color = k;
best = dist;