Added a os_upper_case function

source/kernel/features/strings.asm

@@ -12,7 +12,7 @@ os_compare_strings:
 .compare:
 	lodsb
 	scasb			; Compare di to si
-	jne .unequal		; If they are no equal, jump to .unequal
+	jne .unequal		; If they are not equal, jump to .unequal
 	cmp al, 0		; Check if string is finished
 	je .equal		; If it has, return true
 	jmp .compare		; Finally, repeat
@@ -24,3 +24,26 @@ os_compare_strings:
 .equal:
 	mov cl, 1
 	ret
+
+
+; Convert a string to all upper case
+os_upper_case:
+    pusha
+    mov di, si
+.loop:
+    lodsb
+    inc di
+    cmp al, 0
+    je .finish
+    cmp al, 7Ah
+    jns .loop
+    cmp al, 61h
+    js .loop
+    sub al, 20h
+    dec di
+    stosb
+    jmp .loop
+.finish:
+    popa
+    ret
+