Add a convenience function pb_get_encoded_size()

[apps/agl-service-can-low-level.git] / docs / reference.rst

diff --git a/docs/reference.rst b/docs/reference.rst
index 51556d3..ccbf0a4 100644 (file)
--- a/docs/reference.rst
+++ b/docs/reference.rst
@@ -24,8 +24,8 @@ __BIG_ENDIAN__                 Set this if your platform stores integers and
                                floats in big-endian format. Mixed-endian
                                systems (different layout for ints and floats)
                                are currently not supported.
                                floats in big-endian format. Mixed-endian
                                systems (different layout for ints and floats)
                                are currently not supported.

-NANOPB_INTERNALS               Set this to expose the field encoder functions
-                               that are hidden since nanopb-0.1.3.
+PB_ENABLE_MALLOC               Set this to enable dynamic allocation support
+                               in the decoder.

 PB_MAX_REQUIRED_FIELDS         Maximum number of required fields to check for
                                presence. Default value is 64. Increases stack
                                usage 1 byte per every 8 fields. Compiler
 PB_MAX_REQUIRED_FIELDS         Maximum number of required fields to check for
                                presence. Default value is 64. Increases stack
                                usage 1 byte per every 8 fields. Compiler


@@ -75,8 +75,9 @@ max_count                      Allocated number of entries in arrays
                                (*repeated* fields).
 type                           Type of the generated field. Default value
                                is *FT_DEFAULT*, which selects automatically.
                                (*repeated* fields).
 type                           Type of the generated field. Default value
                                is *FT_DEFAULT*, which selects automatically.

-                               You can use *FT_CALLBACK*, *FT_STATIC* or
-                               *FT_IGNORE* to force a callback field, a static
+                               You can use *FT_CALLBACK*, *FT_POINTER*,
+                               *FT_STATIC* or *FT_IGNORE* to force a callback
+                               field, a dynamically allocated field, a static

                                field or to completely ignore the field.
 long_names                     Prefix the enum name to the enum value in
                                definitions, i.e. *EnumName_EnumValue*. Enabled
                                field or to completely ignore the field.
 long_names                     Prefix the enum name to the enum value in
                                definitions, i.e. *EnumName_EnumValue*. Enabled


@@ -415,6 +416,17 @@ Encodes the contents of a structure as a protocol buffers message and writes it
 
 Normally pb_encode simply walks through the fields description array and serializes each field in turn. However, submessages must be serialized twice: first to calculate their size and then to actually write them to output. This causes some constraints for callback fields, which must return the same data on every call.
 
 
 Normally pb_encode simply walks through the fields description array and serializes each field in turn. However, submessages must be serialized twice: first to calculate their size and then to actually write them to output. This causes some constraints for callback fields, which must return the same data on every call.
 

+pb_encode_delimited
+-------------------
+Calculates the length of the message, encodes it as varint and then encodes the message. ::
+
+    bool pb_encode_delimited(pb_ostream_t *stream, const pb_field_t fields[], const void *src_struct);
+
+(parameters are the same as for `pb_encode`_.)
+
+A common way to indicate the message length in Protocol Buffers is to prefix it with a varint.
+This function does this, and it is compatible with *parseDelimitedFrom* in Google's protobuf library.
+

 .. sidebar:: Encoding fields manually
 
     The functions with names *pb_encode_\** are used when dealing with callback fields. The typical reason for using callbacks is to have an array of unlimited size. In that case, `pb_encode`_ will call your callback function, which in turn will call *pb_encode_\** functions repeatedly to write out values.
 .. sidebar:: Encoding fields manually
 
     The functions with names *pb_encode_\** are used when dealing with callback fields. The typical reason for using callbacks is to have an array of unlimited size. In that case, `pb_encode`_ will call your callback function, which in turn will call *pb_encode_\** functions repeatedly to write out values.


@@ -577,6 +589,10 @@ In addition to EOF, the pb_decode implementation supports terminating a message
 
 For optional fields, this function applies the default value and sets *has_<field>* to false if the field is not present.
 
 
 For optional fields, this function applies the default value and sets *has_<field>* to false if the field is not present.
 

+If *PB_ENABLE_MALLOC* is defined, this function may allocate storage for any pointer type fields.
+In this case, you have to call `pb_release`_ to release the memory after you are done with the message.
+On error return `pb_decode` will release the memory itself.
+

 pb_decode_noinit
 ----------------
 Same as `pb_decode`_, except does not apply the default values to fields. ::
 pb_decode_noinit
 ----------------
 Same as `pb_decode`_, except does not apply the default values to fields. ::


@@ -587,6 +603,35 @@ Same as `pb_decode`_, except does not apply the default values to fields. ::
 
 The destination structure should be filled with zeros before calling this function. Doing a *memset* manually can be slightly faster than using `pb_decode`_ if you don't need any default values.
 
 
 The destination structure should be filled with zeros before calling this function. Doing a *memset* manually can be slightly faster than using `pb_decode`_ if you don't need any default values.
 

+In addition to decoding a single message, this function can be used to merge two messages, so that
+values from previous message will remain if the new message does not contain a field.
+
+This function *will not* release the message even on error return. If you use *PB_ENABLE_MALLOC*,
+you will need to call `pb_release`_ yourself.
+
+pb_decode_delimited
+-------------------
+Same as `pb_decode`_, except that it first reads a varint with the length of the message. ::
+
+    bool pb_decode_delimited(pb_istream_t *stream, const pb_field_t fields[], void *dest_struct);
+
+(parameters are the same as for `pb_decode`_.)
+
+A common method to indicate message size in Protocol Buffers is to prefix it with a varint.
+This function is compatible with *writeDelimitedTo* in the Google's Protocol Buffers library.
+
+pb_release
+----------
+Releases any dynamically allocated fields.
+
+    void pb_release(const pb_field_t fields[], void *dest_struct);
+
+:fields:        A field description array. Usually autogenerated.
+:dest_struct:   Pointer to structure where data will be stored.
+
+This function is only available if *PB_ENABLE_MALLOC* is defined. It will release any
+pointer type fields in the structure and set the pointers to NULL.
+

 pb_skip_varint
 --------------
 Skip a varint_ encoded integer without decoding it. ::
 pb_skip_varint
 --------------
 Skip a varint_ encoded integer without decoding it. ::