[BOOT] Multiboot compliant kernel which runs 64 bit code

kernel/boot/kmain.c

@@ -0,0 +1,34 @@
+#include <mem.h>
+
+#define VGA_MEMORY 0xb8000
+#define VGA_ROWS 24
+#define VGA_COLS 80
+
+void clear_screen()
+{
+  // Clear the video memory
+  unsigned char *m = (void *)P2V(VGA_MEMORY);
+  for(int i = 0; i < VGA_ROWS*VGA_COLS*2; i++)
+  {
+    *m++ = 0;
+  }
+}
+
+void prints(const char *s, unsigned int row, unsigned int col)
+{
+  // Very simple pure ascii string printing
+  unsigned char *m = (void *)P2V(VGA_MEMORY);
+  m += 2*VGA_COLS*row+2*col;
+  while(*s)
+  {
+    *m++ = *s++;
+    *m++ = 0x7;
+  }
+}
+
+int kmain(void)
+{
+  clear_screen();
+  prints("Hello, world!", 0, 0);
+  for(;;)asm("hlt");
+}