Implement enough functionality to compile & match pokecrystal

src/gfx/rgba.cpp

@@ -0,0 +1,24 @@
+
+#include "gfx/rgba.hpp"
+
+#include <assert.h>
+#include <stdint.h>
+
+#include "gfx/main.hpp" // options
+
+uint16_t Rgba::cgbColor() const {
+	if (isTransparent()) {
+		return transparent;
+	}
+	if (options.useColorCurve) {
+		assert(!"TODO");
+	} else {
+		return (red >> 3) | (green >> 3) << 5 | (blue >> 3) << 10;
+	}
+}
+
+uint8_t Rgba::grayIndex() const {
+	assert(isGray());
+	// Convert from [0; 256[ to [0; maxPalSize[
+	return static_cast<uint16_t>(255 - red) * options.maxPalSize() / 256;
+}