Add some missing 'static' specifiers

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

diff --git a/docs/reference.rst b/docs/reference.rst
index 42f4864..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


@@ -49,6 +49,11 @@ PB_BUFFER_ONLY                 Disables the support for custom streams. Only
 PB_OLD_CALLBACK_STYLE          Use the old function signature (void\* instead
                                of void\*\*) for callback fields. This was the
                                default until nanopb-0.2.1.
 PB_OLD_CALLBACK_STYLE          Use the old function signature (void\* instead
                                of void\*\*) for callback fields. This was the
                                default until nanopb-0.2.1.

+PB_SYSTEM_HEADER               Replace the standard header files with a single
+                               header file. It should define all the required
+                               functions and typedefs listed on the
+                               `overview page`_. Value must include quotes,
+                               for example *#define PB_SYSTEM_HEADER "foo.h"*.

 ============================  ================================================
 
 The PB_MAX_REQUIRED_FIELDS, PB_FIELD_16BIT and PB_FIELD_32BIT settings allow
 ============================  ================================================
 
 The PB_MAX_REQUIRED_FIELDS, PB_FIELD_16BIT and PB_FIELD_32BIT settings allow


@@ -56,7 +61,7 @@ raising some datatype limits to suit larger messages. Their need is recognized
 automatically by C-preprocessor #if-directives in the generated .pb.h files.
 The default setting is to use the smallest datatypes (least resources used).
 
 automatically by C-preprocessor #if-directives in the generated .pb.h files.
 The default setting is to use the smallest datatypes (least resources used).
 

-
+.. _`overview page`: index.html#compiler-requirements

 
 
 Proto file options
 
 
 Proto file options


@@ -70,8 +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


@@ -299,6 +305,41 @@ Protocol Buffers wire types. These are used with `pb_encode_tag`_. ::
         PB_WT_32BIT  = 5
     } pb_wire_type_t;
 
         PB_WT_32BIT  = 5
     } pb_wire_type_t;
 

+pb_extension_type_t
+-------------------
+Defines the handler functions and auxiliary data for a field that extends
+another message. Usually autogenerated by *nanopb_generator.py*::
+
+    typedef struct {
+        bool (*decode)(pb_istream_t *stream, pb_extension_t *extension,
+                   uint32_t tag, pb_wire_type_t wire_type);
+        bool (*encode)(pb_ostream_t *stream, const pb_extension_t *extension);
+        const void *arg;
+    } pb_extension_type_t;
+
+In the normal case, the function pointers are *NULL* and the decoder and
+encoder use their internal implementations. The internal implementations
+assume that *arg* points to a *pb_field_t* that describes the field in question.
+
+To implement custom processing of unknown fields, you can provide pointers
+to your own functions. Their functionality is mostly the same as for normal
+callback fields, except that they get called for any unknown field when decoding.
+
+pb_extension_t
+--------------
+Ties together the extension field type and the storage for the field value::
+
+    typedef struct {
+        const pb_extension_type_t *type;
+        void *dest;
+        pb_extension_t *next;
+    } pb_extension_t;
+
+:type:      Pointer to the structure that defines the callback functions.
+:dest:      Pointer to the variable that stores the field value
+            (as used by the default extension callback functions.)
+:next:      Pointer to the next extension handler, or *NULL*.
+

 PB_GET_ERROR
 ------------
 Get the current error message from a stream, or a placeholder string if
 PB_GET_ERROR
 ------------
 Get the current error message from a stream, or a placeholder string if


@@ -375,6 +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.


@@ -537,6 +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. ::


@@ -547,6 +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. ::