Fixed some bugs with inputs

source/kernel/features/strings.asm

@@ -107,7 +107,7 @@ string_join:
 
 ; ------------------------------------------------------------------------
 ; TODO
-; Converts a null terminated string to an integer
+; Converts a string to an integer
 ; IN: SI = string location (max 5 chars, up to '65536')
 ; OUT: AX = number
 string_cast_to_int:
@@ -116,8 +116,12 @@ string_cast_to_int:
 	.loop:
 		xor ax,ax
 		lodsb
-		cmp al, 0
-		je .finish
+
+		cmp al, 30h
+		jl .finish
+		cmp al, 39h
+		jg .finish
+
 		sub al, 30h
 		mov bx, ax
 		mov ax, 10