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Diffstat (limited to 'docs/encoding.rst')
| -rw-r--r-- | docs/encoding.rst | 31 |
1 files changed, 5 insertions, 26 deletions
diff --git a/docs/encoding.rst b/docs/encoding.rst index e4e0cd7..3f673f3 100644 --- a/docs/encoding.rst +++ b/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.
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