More documentation, small improvements

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

docs/encoding.rst

@@ -4,36 +4,15 @@ Nanopb: Encoding messages
 
 The basic way to encode messages is to:
 
-1) Write a callback function for whatever stream you want to write the message to.
+1) Create an `output stream`_.
 2) Fill a structure with your data.
-3) Call pb_encode with the stream, a pointer to *const pb_field_t* array and a pointer to your structure.
+3) Call *pb_encode* with the stream, a pointer to *const pb_field_t* array and a pointer to your structure.
 
 A few extra steps are necessary if you need to know the size of the message beforehand, or if you have dynamically sized fields.
 
-Output streams
-==============
+.. _`output stream`: concepts.html#output-streams
 
-This is the contents of *pb_ostream_t* structure::
+Function: pb_encode
+===================
 
- typedef struct _pb_ostream_t pb_ostream_t;
- struct _pb_ostream_t
- {
-    bool (*callback)(pb_ostream_t *stream, const uint8_t *buf, size_t count);
-    void *state;
-    size_t max_size;
-    size_t bytes_written;
- };
 
-This, combined with the pb_write function, provides a light-weight abstraction
-for whatever destination you want to write data to.
-
-*callback* should be a pointer to your callback function. These are the rules for it:
-
-1) Return false on IO errors. This will cause encoding to abort.
- * 
- * 2) You can use state to store your own data (e.g. buffer pointer).
- * 
- * 3) pb_write will update bytes_written after your callback runs.
- * 
- * 4) Substreams will modify max_size and bytes_written. Don't use them to
- * calculate any pointers.