Move src/modules/main -> src/kernel

src/kernel/screen.cpp

@@ -0,0 +1,77 @@
+#include "screen.h"
+
+template <typename T>
+static int popcount(T x)
+{
+	int c = 0;
+	while (x) {
+		c += (x & 1);
+		x = x >> 1;
+	}
+	return c;
+}
+
+template <typename T>
+static int ctz(T x)
+{
+	int c = 0;
+	while ((x & 1) == 0) {
+		x = x >> 1;
+		++c;
+	}
+	return c;
+}
+
+screen::color_masks::color_masks(pixel_t r, pixel_t g, pixel_t b) :
+	r(r), g(g), b(b)
+{
+	rshift = static_cast<uint8_t>(ctz(r) - (8 - popcount(r)));
+	gshift = static_cast<uint8_t>(ctz(g) - (8 - popcount(g)));
+	bshift = static_cast<uint8_t>(ctz(b) - (8 - popcount(b)));
+}
+
+screen::color_masks::color_masks(const color_masks &o) :
+	rshift(o.rshift), gshift(o.gshift), bshift(o.bshift),
+	r(o.r), g(o.g), b(o.b)
+{
+}
+
+screen::screen(
+		void *framebuffer,
+		unsigned hres, unsigned vres,
+		pixel_t rmask, pixel_t gmask, pixel_t bmask) :
+	m_framebuffer(static_cast<pixel_t *>(framebuffer)),
+	m_masks(rmask, gmask, bmask),
+	m_resolution(hres, vres)
+{
+}
+
+screen::screen(const screen &other) :
+	m_framebuffer(other.m_framebuffer),
+	m_masks(other.m_masks),
+	m_resolution(other.m_resolution)
+{
+}
+
+screen::pixel_t
+screen::color(uint8_t r, uint8_t g, uint8_t b) const
+{
+	return
+		((static_cast<uint32_t>(r) << m_masks.rshift) & m_masks.r) |
+		((static_cast<uint32_t>(g) << m_masks.gshift) & m_masks.g) |
+		((static_cast<uint32_t>(b) << m_masks.bshift) & m_masks.b);
+}
+
+void
+screen::fill(pixel_t color)
+{
+	const size_t len = m_resolution.size();
+	for (size_t i = 0; i < len; ++i)
+		m_framebuffer[i] = color;
+}
+
+void
+screen::draw_pixel(unsigned x, unsigned y, pixel_t color)
+{
+	m_framebuffer[x + y * m_resolution.x] = color;
+}