fbcon: Saner 16-color to 4-color conversion

Currently, the default linux 16-colors are converted to 4-colors by simply dividing the values by 4. However, this is not necessarily correct since the first 4 colors are converted to black, rendering them invisible.

So, for black, no conversion; for light colors, convert to gray, for normal text color, no conversion, and for bright colors, convert to intense white.

From: Antonino Daplas <[email protected]>

---

fbcon.c | 21 +++++++++++++++++++--

1 files changed, 19 insertions(+), 2 deletions(-)

@@ -247,9 +247,26 @@ static inline int get_color(struct vc_da

	case 2:
		/*
		 * Scale down 16-colors to 4 colors. Default 4-color palette

- * is grayscale.
+ * is grayscale. However, simply dividing the values by 4
+ * will not work, as colors 1, 2 and 3 will be scaled-down
+ * to zero rendering them invisible. So empirically convert
+ * colors to a sane 4-level grayscale.

		 */

- color /= 4;
+ switch (color) {
+ case 0:
+ color = 0; /* black */
+ break;
+ case 1 ... 6:
+ color = 2; /* white */
+ break;
+ case 7 ... 8:
+ color = 1; /* gray */
+ break;
+ default:
+ color = 3; /* intense white */
+ break;
+ }

+		break;
	case 3:
		/*
		 * Last 8 entries of default 16-color palette is a more intense

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