1 files changed, 54 insertions, 0 deletions
diff --git a/src/boot/multiboot.c b/src/boot/multiboot.c
new file mode 100644
index 0000000..0309eb0
--- /dev/null
+++ b/src/boot/multiboot.c
@@ -0,0 +1,54 @@
+#include "multiboot.h"
+#include "utils/mem.h"
+
+/// See boot.S
+extern u8* MB_INFO;
+
+char mb_load_tag(char **data, char type){
+    char *c_info_size=MB_INFO;
+    char *c_tag_type=c_info_size+8;
+    char *c_tag_size=c_info_size+12;
+
+    int max_size=*((int*)c_info_size);
+    while(((int)c_tag_type-(int)MB_INFO)<max_size){       
+        int tag_type=*((int*)c_tag_type);
+        int tag_size=*((int*)c_tag_size);
+        if(tag_type==type){
+            *data=c_tag_type;
+            return 0;
+        }
+
+        c_tag_type=c_tag_type+tag_size+4;
+        // Skip padding for 64 bits
+        int p=c_tag_type;
+        while((p & 0x7) != 0)
+            p++;
+        // Assign address after padding
+        c_tag_type=p;
+        c_tag_size=c_tag_type+4;
+
+    }
+    return 1;
+}
+char mb_load_bl_name(MBI_TAG_BL_NAME *data){
+    char *to_load;
+    if(!mb_load_tag(&to_load,2)){
+        memcpy(to_load,data,8);
+        to_load+=8;
+        data->name=to_load;
+        return 0;
+    }
+    return 1;
+}
+
+char mb_load_fb(MBI_TAG_FB *data){
+    char *to_load;
+    if(!mb_load_tag(&to_load,8)){
+        asm("mov %0, %%ecx;aa:;jmp aa;"::"r"(to_load));
+        memcpy(to_load,data,8);
+        to_load+=8;
+        memcpy(to_load,&(data->framebuffer_addr),8);
+        return 0;
+    }
+    return 1;
+}