Call C function

.gitignore

@@ -2,4 +2,5 @@ boot.bin
 dittoOS.img
 **/*.o
 **/*.elf
-**/*.iso
+**/*.iso
+bochslog.txt

kmain.c

@@ -1,9 +1,27 @@
+void fb_write_cell(unsigned int i, char c, unsigned char fg, unsigned char bg);
+
+
 int main() {
+    fb_write_cell(0, 'A', 2, 8);
     return 0;
 }
 
-int sum_of_three(int arg1, int arg2, int arg3) {
-    return arg1 + arg2 + arg3;
+/** fb_write_cell:
+    *  Writes a character with the given foreground and background to position i
+    *  in the framebuffer.
+
+    * 
+    *  @param i  The location in the framebuffer
+    *  @param c  The character
+    *  @param fg The foreground color
+    *  @param bg The background color
+    *
+    *  @example fb_write_cell(0, 'A', 2, 8);
+    */
+void fb_write_cell(unsigned int i, char c, unsigned char fg, unsigned char bg) {
+    char *fb = (char *) 0x000B8000;
+    fb[i] = c;
+    fb[i + 1] = ((fg & 0x0F) << 4) | (bg & 0x0F);
 }
 
 struct example {

loader.s

@@ -1,5 +1,5 @@
 global loader                   ; the entry symbol for ELF
-extern sum_of_three
+extern main
 
 MAGIC_NUMBER equ 0x1BADB002     ; define the magic number constant
 FLAGS        equ 0x0            ; multiboot flags
@@ -24,10 +24,6 @@ loader:                         ; the loader label (defined as entry point in li
 
     mov esp, kernel_stack + KERNEL_STACK_SIZE   ; point esp to the start of the
                                                 ; stack (end of memory area)
-
-    push dword 3            ; arg3
-    push dword 2            ; arg2
-    push dword 1            ; arg1
-    call sum_of_three       ; call the function, the result will be in eax
+    call main
 .loop:
     jmp .loop                   ; loop forever