lesson 23, initial commit

23-fixes/boot/print.asm

@@ -0,0 +1,37 @@
+print:
+    pusha
+
+; keep this in mind:
+; while (string[i] != 0) { print string[i]; i++ }
+
+; the comparison for string end (null byte)
+start:
+    mov al, [bx] ; 'bx' is the base address for the string
+    cmp al, 0 
+    je done
+
+    ; the part where we print with the BIOS help
+    mov ah, 0x0e
+    int 0x10 ; 'al' already contains the char
+
+    ; increment pointer and do next loop
+    add bx, 1
+    jmp start
+
+done:
+    popa
+    ret
+
+
+
+print_nl:
+    pusha
+    
+    mov ah, 0x0e
+    mov al, 0x0a ; newline char
+    int 0x10
+    mov al, 0x0d ; carriage return
+    int 0x10
+    
+    popa
+    ret