make symbols and add nil

stage2/include/lisp.h

@@ -3,7 +3,7 @@
 
 #define     SYMBOL_TABLE_SIZE       2048
 
-typedef char *  symbol_t;
+typedef unsigned int  symbol_t;
 
 #define     TYPE_SYMBOL     1
 #define     TYPE_NUMBER     2
@@ -18,7 +18,6 @@ typedef char *  symbol_t;
 #define     floatp(x)       (x->type == TYPE_FLOAT)
 #define     listp(x)        (x->type == TYPE_LIST)
 
-
 typedef struct cell {
     uint8_t                 type;
     union {
@@ -35,5 +34,14 @@ typedef struct cell {
             };
         };
     };
-} cell_t;
+};
 
+
+symbol_t     intern_symbol(const char *s);
+symbol_t     make_symbol(const char *s);
+
+static auto NIL = make_symbol("nil");
+
+
+cell  head(cell x);
+cell  tail(cell x);

stage2/include/neopixel.h

@@ -3,6 +3,7 @@
 namespace neopxl {
 
 void        start();
-bool        blink(bool);
+void        blink();
+void        stop();
 
 } // namespace neopxl