added a buffer of 64 bytes for some easily accesible persistent storage accesable via p@ and p!

stdlib/stdlib.sl

@@ -1,3 +1,30 @@
+# Reserve 64 bytes in .bss
+# persistent: resb 64
+
+# : p@ ( offset -- n )
+:asm p@ {
+	mov rax, [r12]         ; offset
+	lea rbx, [rel persistent]
+	add rax, rbx           ; address = persistent + offset
+	mov rax, [rax]         ; load value
+	mov [r12], rax         ; store on stack
+	ret
+}
+;
+
+# : p! ( value offset -- )
+:asm p! {
+	mov rbx, [r12]         ; offset
+	add r12, 8
+	mov rax, [r12]         ; value
+	lea rcx, [rel persistent]
+	add rcx, rbx           ; address = persistent + offset
+	mov [rcx], rax         ; store value
+	add r12, 8             ; pop value
+	ret
+}
+;
+
 # : strlen ( addr -- len )
 # for null terminated strings