1 files changed, 41 insertions, 0 deletions
diff --git a/kernel/src/boot/multiboot2.c b/kernel/src/boot/multiboot2.c
new file mode 100644
index 0000000..e228ce1
--- /dev/null
+++ b/kernel/src/boot/multiboot2.c
@@ -0,0 +1,41 @@
+#include <stdint.h>
+#include <multiboot2.h>
+#include <graphics.h>
+
+fb_t fb;
+
+/* https://www.gnu.org/software/grub/manual/multiboot2/html_node/Boot-information-format.html */
+
+void init_fb(mb2_tag_header* multiboot_bootinfo, uint32_t multiboot_magic)
+{
+	if (multiboot_magic != MB2_MAGIC) {
+		// not loaded by multiboot2 bootloader
+		__asm__ volatile ("hlt;");
+	}
+
+	// we will store framebuffer information here
+	static mb2_tag_fb* tag_fb;
+
+	// skip first 8 bytes (total_size + reserved)
+	mb2_tag_header* tag_header = multiboot_bootinfo + 1;
+
+	while (tag_header->type != MB2_TAG_END) {
+		// process tag_type
+		switch(tag_header->type) {
+			case MB2_TAG_FB:
+				tag_fb = (mb2_tag_fb*)tag_header;
+				break;
+			default:
+				break;
+		}
+
+		// next mb2_tag
+		tag_header += tag_header->size / 8 + ((tag_header->size % 8) > 0);
+	}
+
+	fb.addr = tag_fb->framebuffer_addr;
+	fb.width = tag_fb->framebuffer_width;
+	fb.height = tag_fb->framebuffer_height;
+	fb.pitch = tag_fb->framebuffer_pitch;
+	fb.bpp = tag_fb->framebuffer_bpp;
+}