comment

lib/valtype.h

@@ -1,20 +1,25 @@
 #if !defined(_TOYWASM_VALTYPE_H)
 #define _TOYWASM_VALTYPE_H
 
+/*
+ * Note: these values are sN-encoded negative values so that
+ * they can be distinguished from typeidx in eg. block types.
+ */
+
 enum valtype {
         /* numtype */
-        TYPE_i32 = 0x7f,
-        TYPE_i64 = 0x7e,
-        TYPE_f32 = 0x7d,
-        TYPE_f64 = 0x7c,
+        TYPE_i32 = 0x7f, /* -0x01 */
+        TYPE_i64 = 0x7e, /* -0x02 */
+        TYPE_f32 = 0x7d, /* -0x03 */
+        TYPE_f64 = 0x7c, /* -0x04 */
 
         /* vectype */
-        TYPE_v128 = 0x7b,
+        TYPE_v128 = 0x7b, /* -0x05 */
 
         /* reftype */
-        TYPE_EXNREF = 0x69,
-        TYPE_FUNCREF = 0x70,
-        TYPE_EXTERNREF = 0x6f,
+        TYPE_EXNREF = 0x69,    /* -0x17 */
+        TYPE_FUNCREF = 0x70,   /* -0x10 */
+        TYPE_EXTERNREF = 0x6f, /* -0x11 */
 
         /* pseudo types for validation logic */
         TYPE_ANYREF = 0xfe, /* any reftype */