Signed int print

main.asm

@@ -5,8 +5,15 @@
 section KERNEL follows=BOOTSECTOR vstart=1000h
 
 main:
-    mov bx, 65535
-    call print_uint
+    mov bx, 156
+    call print_sint
+    
+    ;mov ax, -20
+    ;mov dx, 0x0003
+    ;mov cx, 10
+    ;idiv cx
+    ;mov bx, ax
+    ;call print_uint
     
 jmp $ ; Halt
     

print_util.asm

@@ -1,3 +1,19 @@
+%macro print_ch 1
+       push ax
+       mov al, %1
+       mov ah, 0x0e
+       int 0x10
+       pop ax
+%endmacro
+
+%macro cls 0
+    mov ax, 0x0600 ; AH=06 Scroll screen, AL=0 Clear screen
+    mov bh, 0x0F ; black bg, white fg
+    mov cx, 0x0000 ; x1=y1=0
+    mov dx, 0x5019 ; 89x25
+    int 0x10 ; Graphics services
+%endmacro
+
 print:
     pusha
     
@@ -128,7 +144,7 @@ print_uint:
     
     .loop:
         mov cx, 10
-        mov dx, 0   ; IMPORTANT: Division will not work unless the remainder register is set to 0 beforehand
+        mov dx, 0   ; IMPORTANT: Division will not work unless the higher register is in a usable length
         div cx      ; Divide ax by cx (10), -> ax, rem -> dx
         
         add dx, 0x30 ; Add ascii '0'
@@ -152,20 +168,20 @@ print_uint:
     popa
     ret
     
-_print_dec_buff: resb 6
 
-%macro print_ch 1
-       push ax
-       mov al, [%1]
-       mov ah, 0x0e
-       int 0x10
-       pop ax
-%endmacro
+print_sint:
+    pusha
     
-%macro cls 0
-    mov ax, 0x0600 ; AH=06 Scroll screen, AL=0 Clear screen
-    mov bh, 0x0F ; black bg, white fg
-    mov cx, 0x0000 ; x1=y1=0
-    mov dx, 0x5019 ; 89x25
-    int 0x10 ; Graphics services
-%endmacro
+    ; Old (non-working method) used a copy of above with idiv. I think this way is smarter
+    
+    test bx, 0x8000 ; Check sign-bit
+    jz .positive
+    
+    print_ch '-'
+    neg bx
+    
+    .positive:
+    call print_uint
+        
+    popa
+    ret