added neg and bitnot to the stdlib and made a fib.sl example

fib.sl

@@ -0,0 +1,16 @@
+import stdlib/stdlib.sl
+import stdlib/io.sl
+
+: main
+    1 1 2dup 2dup puti cr puti cr
+    +
+    dup puti cr
+    rot
+    22 dup >r for
+        2dup + dup puti cr
+        rot
+    next
+    "-------" puts
+    r> 3 + puti
+    " numbers printed from the fibonaci sequence" puts
+;

stdlib/stdlib.sl

@@ -413,3 +413,19 @@
 	mov [r12], rax         ; push value
 }
 ;
+
+# : neg ( x -- -x )
+:asm neg {
+    mov rax, [r12]   ; get value
+    neg rax          ; arithmetic negation
+    mov [r12], rax   ; store result
+}
+;
+
+# : bitnot ( 0|1 -- 1|0 )
+:asm bitnot {
+    mov rax, [r12]   ; get value
+    xor rax, 1       ; flip lowest bit
+    mov [r12], rax   ; store result
+}
+;