More documentation, small improvements

git-svn-id: https://svn.kapsi.fi/jpa/nanopb@955 e3a754e5-d11d-0410-8d38-ebb782a927b9

pb.h

@@ -1,6 +1,11 @@
 #ifndef _PB_H_
 #define _PB_H_
 
+/* pb.h: Common parts for nanopb library.
+ * Most of these are quite low-level stuff. For the high-level interface,
+ * see pb_encode.h or pb_decode.h
+ */
+
 #include <stdint.h>
 #include <stddef.h>
 #include <stdbool.h>
@@ -12,15 +17,7 @@
 #define pb_packed
 #endif
 
-/* Wire types. Library user needs these only in encoder callbacks. */
-typedef enum {
-    PB_WT_VARINT = 0,
-    PB_WT_64BIT  = 1,
-    PB_WT_STRING = 2,
-    PB_WT_32BIT  = 5
-} pb_wire_type_t;
-
-/* List of possible field types
+/* List of possible field types. These are used in the autogenerated code.
  * Least-significant 4 bits tell the scalar type
  * Most-significant 4 bits specify repeated/required/packed etc.
  * 
@@ -143,10 +140,19 @@ struct _pb_callback_t {
     void *arg;
 };
 
+/* Wire types. Library user needs these only in encoder callbacks. */
+typedef enum {
+    PB_WT_VARINT = 0,
+    PB_WT_64BIT  = 1,
+    PB_WT_STRING = 2,
+    PB_WT_32BIT  = 5
+} pb_wire_type_t;
+
 /* These macros are used to declare pb_field_t's in the constant array. */
 #define pb_membersize(st, m) (sizeof ((st*)0)->m)
 #define pb_arraysize(st, m) (pb_membersize(st, m) / pb_membersize(st, m[0]))
 #define pb_delta(st, m1, m2) ((int)offsetof(st, m1) - (int)offsetof(st, m2))
+#define pb_delta_end(st, m1, m2) (offsetof(st, m1) - offsetof(st, m2) - pb_membersize(st, m2))
 #define PB_LAST_FIELD {0,0,0,0}