.. contents ::
+
+
+
+Compilation options
+===================
+The following options can be specified in one of two ways:
+
+1. Using the -D switch on the C compiler command line.
+2. By #defining them at the top of pb.h.
+
+You must have the same settings for the nanopb library and all code that
+includes pb.h.
+
+============================ ================================================
+PB_NO_PACKED_STRUCTS Disable packed structs. Increases RAM usage but
+ is necessary on some platforms that do not
+ support unaligned memory access.
+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
+ warning will tell if you need this.
+PB_FIELD_16BIT Add support for tag numbers > 255 and fields
+ larger than 255 bytes or 255 array entries.
+ Increases code size 3 bytes per each field.
+ Compiler error will tell if you need this.
+PB_FIELD_32BIT Add support for tag numbers > 65535 and fields
+ larger than 65535 bytes or 65535 array entries.
+ Increases code size 9 bytes per each field.
+ Compiler error will tell if you need this.
+PB_NO_ERRMSG Disables the support for error messages; only
+ error information is the true/false return
+ value. Decreases the code size by a few hundred
+ bytes.
+PB_BUFFER_ONLY Disables the support for custom streams. Only
+ supports encoding and decoding with memory
+ buffers. Speeds up execution and decreases code
+ size slightly.
+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
+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).
+
+.. _`overview page`: index.html#compiler-requirements
+
+
+Proto file options
+==================
+The generator behaviour can be adjusted using these options, defined in the
+'nanopb.proto' file in the generator folder:
+
+============================ ================================================
+max_size Allocated size for *bytes* and *string* fields.
+max_count Allocated number of entries in arrays
+ (*repeated* fields).
+int_size Override the integer type of a field.
+ (To use e.g. uint8_t to save RAM.)
+type Type of the generated field. Default value
+ is *FT_DEFAULT*, which selects automatically.
+ 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
+ by default.
+packed_struct Make the generated structures packed.
+ NOTE: This cannot be used on CPUs that break
+ on unaligned accesses to variables.
+skip_message Skip the whole message from generation.
+no_unions Generate 'oneof' fields as optional fields
+ instead of C unions.
+msgid Specifies a unique id for this message type.
+ Can be used by user code as an identifier.
+============================ ================================================
+
+These options can be defined for the .proto files before they are converted
+using the nanopb-generatory.py. There are three ways to define the options:
+
+1. Using a separate .options file.
+ This is the preferred way as of nanopb-0.2.1, because it has the best
+ compatibility with other protobuf libraries.
+2. Defining the options on the command line of nanopb_generator.py.
+ This only makes sense for settings that apply to a whole file.
+3. Defining the options in the .proto file using the nanopb extensions.
+ This is the way used in nanopb-0.1, and will remain supported in the
+ future. It however sometimes causes trouble when using the .proto file
+ with other protobuf libraries.
+
+The effect of the options is the same no matter how they are given. The most
+common purpose is to define maximum size for string fields in order to
+statically allocate them.
+
+Defining the options in a .options file
+---------------------------------------
+The preferred way to define options is to have a separate file
+'myproto.options' in the same directory as the 'myproto.proto'. ::
+
+ # myproto.proto
+ message MyMessage {
+ required string name = 1;
+ repeated int32 ids = 4;
+ }
+
+::
+
+ # myproto.options
+ MyMessage.name max_size:40
+ MyMessage.ids max_count:5
+
+The generator will automatically search for this file and read the
+options from it. The file format is as follows:
+
+* Lines starting with '#' or '//' are regarded as comments.
+* Blank lines are ignored.
+* All other lines should start with a field name pattern, followed by one or
+ more options. For example: *"MyMessage.myfield max_size:5 max_count:10"*.
+* The field name pattern is matched against a string of form *'Message.field'*.
+ For nested messages, the string is *'Message.SubMessage.field'*.
+* The field name pattern may use the notation recognized by Python fnmatch():
+
+ - *\** matches any part of string, like 'Message.\*' for all fields
+ - *\?* matches any single character
+ - *[seq]* matches any of characters 's', 'e' and 'q'
+ - *[!seq]* matches any other character
+
+* The options are written as *'option_name:option_value'* and several options
+ can be defined on same line, separated by whitespace.
+* Options defined later in the file override the ones specified earlier, so
+ it makes sense to define wildcard options first in the file and more specific
+ ones later.
+
+If preferred, the name of the options file can be set using the command line
+switch *-f* to nanopb_generator.py.
+
+Defining the options on command line
+------------------------------------
+The nanopb_generator.py has a simple command line option *-s OPTION:VALUE*.
+The setting applies to the whole file that is being processed.
+
+Defining the options in the .proto file
+---------------------------------------
+The .proto file format allows defining custom options for the fields.
+The nanopb library comes with *nanopb.proto* which does exactly that, allowing
+you do define the options directly in the .proto file::
+
+ import "nanopb.proto";
+
+ message MyMessage {
+ required string name = 1 [(nanopb).max_size = 40];
+ repeated int32 ids = 4 [(nanopb).max_count = 5];
+ }
+
+A small complication is that you have to set the include path of protoc so that
+nanopb.proto can be found. This file, in turn, requires the file
+*google/protobuf/descriptor.proto*. This is usually installed under
+*/usr/include*. Therefore, to compile a .proto file which uses options, use a
+protoc command similar to::
+
+ protoc -I/usr/include -Inanopb/generator -I. -omessage.pb message.proto
+
+The options can be defined in file, message and field scopes::
+
+ option (nanopb_fileopt).max_size = 20; // File scope
+ message Message
+ {
+ option (nanopb_msgopt).max_size = 30; // Message scope
+ required string fieldsize = 1 [(nanopb).max_size = 40]; // Field scope
+ }
+
+
+
+
+
+
+
+
+
pb.h
====
---------
Defines the encoder/decoder behaviour that should be used for a field. ::
- typedef enum { ... } pb_type_t;
+ typedef uint8_t pb_type_t;
-The low-order byte of the enumeration values defines the function that can be used for encoding and decoding the field data:
+The low-order nibble of the enumeration values defines the function that can be used for encoding and decoding the field data:
==================== ===== ================================================
LTYPE identifier Value Storage format
==================== ===== ================================================
PB_LTYPE_VARINT 0x00 Integer.
PB_LTYPE_SVARINT 0x01 Integer, zigzag encoded.
-PB_LTYPE_FIXED 0x02 Integer or floating point.
-PB_LTYPE_BYTES 0x03 Structure with *size_t* field and byte array.
-PB_LTYPE_STRING 0x04 Null-terminated string.
-PB_LTYPE_SUBMESSAGE 0x05 Submessage structure.
+PB_LTYPE_FIXED32 0x02 32-bit integer or floating point.
+PB_LTYPE_FIXED64 0x03 64-bit integer or floating point.
+PB_LTYPE_BYTES 0x04 Structure with *size_t* field and byte array.
+PB_LTYPE_STRING 0x05 Null-terminated string.
+PB_LTYPE_SUBMESSAGE 0x06 Submessage structure.
==================== ===== ================================================
-The high-order byte defines whether the field is required, optional, repeated or callback:
+The bits 4-5 define whether the field is required, optional or repeated:
==================== ===== ================================================
HTYPE identifier Value Field handling
PB_HTYPE_REQUIRED 0x00 Verify that field exists in decoded message.
PB_HTYPE_OPTIONAL 0x10 Use separate *has_<field>* boolean to specify
whether the field is present.
-PB_HTYPE_ARRAY 0x20 A repeated field with preallocated array.
+ (Unless it is a callback)
+PB_HTYPE_REPEATED 0x20 A repeated field with preallocated array.
Separate *<field>_count* for number of items.
-PB_HTYPE_CALLBACK 0x30 A field with dynamic storage size, data is
- actually a pointer to a structure containing a
- callback function.
+ (Unless it is a callback)
==================== ===== ================================================
+The bits 6-7 define the how the storage for the field is allocated:
+
+==================== ===== ================================================
+ATYPE identifier Value Allocation method
+==================== ===== ================================================
+PB_ATYPE_STATIC 0x00 Statically allocated storage in the structure.
+PB_ATYPE_CALLBACK 0x40 A field with dynamic storage size. Struct field
+ actually contains a pointer to a callback
+ function.
+==================== ===== ================================================
+
+
pb_field_t
----------
Describes a single structure field with memory position in relation to others. The descriptions are usually autogenerated. ::
} pb_packed;
:tag: Tag number of the field or 0 to terminate a list of fields.
-:type: LTYPE and HTYPE of the field.
+:type: LTYPE, HTYPE and ATYPE of the field.
:data_offset: Offset of field data, relative to the end of the previous field.
:size_offset: Offset of *bool* flag for optional fields or *size_t* count for arrays, relative to field data.
:data_size: Size of a single data entry, in bytes. For PB_LTYPE_BYTES, the size of the byte array inside the containing structure. For PB_HTYPE_CALLBACK, size of the C data type if known.
:array_size: Maximum number of entries in an array, if it is an array type.
:ptr: Pointer to default value for optional fields, or to submessage description for PB_LTYPE_SUBMESSAGE.
-The *uint8_t* datatypes limit the maximum size of a single item to 255 bytes and arrays to 255 items. Compiler will warn "Initializer too large for type" if the limits are exceeded. The types can be changed to larger ones if necessary.
+The *uint8_t* datatypes limit the maximum size of a single item to 255 bytes and arrays to 255 items. Compiler will give error if the values are too large. The types can be changed to larger ones by defining *PB_FIELD_16BIT*.
pb_bytes_array_t
----------------
typedef struct _pb_callback_t pb_callback_t;
struct _pb_callback_t {
union {
- bool (*decode)(pb_istream_t *stream, const pb_field_t *field, void *arg);
- bool (*encode)(pb_ostream_t *stream, const pb_field_t *field, const void *arg);
+ bool (*decode)(pb_istream_t *stream, const pb_field_t *field, void **arg);
+ bool (*encode)(pb_ostream_t *stream, const pb_field_t *field, void * const *arg);
} funcs;
void *arg;
};
-The *arg* is passed to the callback when calling. It can be used to store any information that the callback might need.
+A pointer to the *arg* is passed to the callback when calling. It can be used to store any information that the callback might need.
+
+Previously the function received just the value of *arg* instead of a pointer to it. This old behaviour can be enabled by defining *PB_OLD_CALLBACK_STYLE*.
When calling `pb_encode`_, *funcs.encode* is used, and similarly when calling `pb_decode`_, *funcs.decode* is used. The function pointers are stored in the same memory location but are of incompatible types. You can set the function pointer to NULL to skip the field.
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
+there is no error message::
+
+ #define PB_GET_ERROR(stream) (string expression)
+
+This should be used for printing errors, for example::
+
+ if (!pb_decode(...))
+ {
+ printf("Decode failed: %s\n", PB_GET_ERROR(stream));
+ }
+
+The macro only returns pointers to constant strings (in code memory),
+so that there is no need to release the returned pointer.
+
+PB_RETURN_ERROR
+---------------
+Set the error message and return false::
+
+ #define PB_RETURN_ERROR(stream,msg) (sets error and returns false)
+
+This should be used to handle error conditions inside nanopb functions
+and user callback functions::
+
+ if (error_condition)
+ {
+ PB_RETURN_ERROR(stream, "something went wrong");
+ }
+
+The *msg* parameter must be a constant string.
+
+
+
pb_encode.h
===========
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_varint
-----------------
-Encodes an unsigned integer in the varint_ format. ::
+pb_encode_delimited
+-------------------
+Calculates the length of the message, encodes it as varint and then encodes the message. ::
- bool pb_encode_varint(pb_ostream_t *stream, uint64_t value);
+ bool pb_encode_delimited(pb_ostream_t *stream, const pb_field_t fields[], const void *src_struct);
-:stream: Output stream to write to. 1-10 bytes will be written.
-:value: Value to encode.
-:returns: True on success, false on IO error.
+(parameters are the same as for `pb_encode`_.)
-.. _varint: http://code.google.com/apis/protocolbuffers/docs/encoding.html#varints
+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.
+
+ The tag of a field must be encoded separately with `pb_encode_tag_for_field`_. After that, you can call exactly one of the content-writing functions to encode the payload of the field. For repeated fields, you can repeat this process multiple times.
+
+ Writing packed arrays is a little bit more involved: you need to use `pb_encode_tag` and specify `PB_WT_STRING` as the wire type. Then you need to know exactly how much data you are going to write, and use `pb_encode_varint`_ to write out the number of bytes before writing the actual data. Substreams can be used to determine the number of bytes beforehand; see `pb_encode_submessage`_ source code for an example.
pb_encode_tag
-------------
:stream: Output stream to write to. 1-5 bytes will be written.
:wiretype: PB_WT_VARINT, PB_WT_64BIT, PB_WT_STRING or PB_WT_32BIT
-:field_number: Identifier for the field, defined in the .proto file.
+:field_number: Identifier for the field, defined in the .proto file. You can get it from field->tag.
:returns: True on success, false on IO error.
pb_encode_tag_for_field
FIXED32 PB_WT_32BIT
========================= ============
-pb_encode_string
+pb_encode_varint
----------------
-Writes the length of a string as varint and then contents of the string. Used for writing fields with wire type PB_WT_STRING. ::
+Encodes a signed or unsigned integer in the varint_ format. Works for fields of type `bool`, `enum`, `int32`, `int64`, `uint32` and `uint64`::
- bool pb_encode_string(pb_ostream_t *stream, const uint8_t *buffer, size_t size);
+ bool pb_encode_varint(pb_ostream_t *stream, uint64_t value);
-:stream: Output stream to write to.
-:buffer: Pointer to string data.
-:size: Number of bytes in the string.
+:stream: Output stream to write to. 1-10 bytes will be written.
+:value: Value to encode. Just cast e.g. int32_t directly to uint64_t.
:returns: True on success, false on IO error.
-.. sidebar:: Field encoders
-
- The functions with names beginning with *pb_enc_* are called field encoders. Each PB_LTYPE has an own field encoder, which handles translating from C data into Protocol Buffers data.
+.. _varint: http://code.google.com/apis/protocolbuffers/docs/encoding.html#varints
- By using the *data_size* in the field description and by taking advantage of C casting rules, it has been possible to combine many data types to a single LTYPE. For example, *int32*, *uint32*, *int64*, *uint64*, *bool* and *enum* are all handled by *pb_enc_varint*.
+pb_encode_svarint
+-----------------
+Encodes a signed integer in the 'zig-zagged' format. Works for fields of type `sint32` and `sint64`::
- Each field encoder only encodes the contents of the field. The tag must be encoded separately with `pb_encode_tag_for_field`_.
+ bool pb_encode_svarint(pb_ostream_t *stream, int64_t value);
- You can use the field encoders from your callbacks. Just be aware that the pb_field_t passed to the callback is not directly compatible with most of the encoders. Instead, you must create a new pb_field_t structure and set the data_size according to the data type you pass to *src.
+(parameters are the same as for `pb_encode_varint`_
-pb_enc_varint
--------------
-Field encoder for PB_LTYPE_VARINT. Takes the first *field->data_size* bytes from src, casts them as *uint64_t* and calls `pb_encode_varint`_. ::
+pb_encode_string
+----------------
+Writes the length of a string as varint and then contents of the string. Works for fields of type `bytes` and `string`::
- bool pb_enc_varint(pb_ostream_t *stream, const pb_field_t *field, const void *src);
+ bool pb_encode_string(pb_ostream_t *stream, const uint8_t *buffer, size_t size);
:stream: Output stream to write to.
-:field: Field description structure. Only *data_size* matters.
-:src: Pointer to start of the field data.
+:buffer: Pointer to string data.
+:size: Number of bytes in the string. Pass `strlen(s)` for strings.
:returns: True on success, false on IO error.
-pb_enc_svarint
---------------
-Field encoder for PB_LTYPE_SVARINT. Similar to `pb_enc_varint`_, except first zig-zag encodes the value for more efficient negative number encoding. ::
+pb_encode_fixed32
+-----------------
+Writes 4 bytes to stream and swaps bytes on big-endian architectures. Works for fields of type `fixed32`, `sfixed32` and `float`::
- bool pb_enc_svarint(pb_ostream_t *stream, const pb_field_t *field, const void *src);
+ bool pb_encode_fixed32(pb_ostream_t *stream, const void *value);
-(parameters are the same as for `pb_enc_varint`_)
+:stream: Output stream to write to.
+:value: Pointer to a 4-bytes large C variable, for example `uint32_t foo;`.
+:returns: True on success, false on IO error.
-The number is considered negative if the high-order bit of the value is set. On big endian computers, it is the highest bit of *\*src*. On little endian computers, it is the highest bit of *\*(src + field->data_size - 1)*.
+pb_encode_fixed64
+-----------------
+Writes 8 bytes to stream and swaps bytes on big-endian architecture. Works for fields of type `fixed64`, `sfixed64` and `double`::
-pb_enc_fixed32
---------------
-Field encoder for PB_LTYPE_FIXED32. Writes the data in little endian order. On big endian computers, reverses the order of bytes. ::
+ bool pb_encode_fixed64(pb_ostream_t *stream, const void *value);
- bool pb_enc_fixed32(pb_ostream_t *stream, const pb_field_t *field, const void *src);
+:stream: Output stream to write to.
+:value: Pointer to a 8-bytes large C variable, for example `uint64_t foo;`.
+:returns: True on success, false on IO error.
-:stream: Output stream to write to.
-:field: Not used.
-:src: Pointer to start of the field data.
-:returns: True on success, false on IO error.
+pb_encode_submessage
+--------------------
+Encodes a submessage field, including the size header for it. Works for fields of any message type::
-pb_enc_fixed64
---------------
-Field encoder for PB_LTYPE_FIXED64. Writes the data in little endian order. On big endian computers, reverses the order of bytes. ::
+ bool pb_encode_submessage(pb_ostream_t *stream, const pb_field_t fields[], const void *src_struct);
- bool pb_enc_fixed64(pb_ostream_t *stream, const pb_field_t *field, const void *src);
+:stream: Output stream to write to.
+:fields: Pointer to the autogenerated field description array for the submessage type, e.g. `MyMessage_fields`.
+:src: Pointer to the structure where submessage data is.
+:returns: True on success, false on IO errors, pb_encode errors or if submessage size changes between calls.
-(parameters are the same as for `pb_enc_fixed32`_)
+In Protocol Buffers format, the submessage size must be written before the submessage contents. Therefore, this function has to encode the submessage twice in order to know the size beforehand.
-The same function is used for both integers and doubles. This breaks encoding of double values on architectures where they are mixed endian (primarily some arm processors with hardware FPU).
+If the submessage contains callback fields, the callback function might misbehave and write out a different amount of data on the second call. This situation is recognized and *false* is returned, but garbage will be written to the output before the problem is detected.
-pb_enc_bytes
-------------
-Field encoder for PB_LTYPE_BYTES. Just calls `pb_encode_string`_. ::
- bool pb_enc_bytes(pb_ostream_t *stream, const pb_field_t *field, const void *src);
-:stream: Output stream to write to.
-:field: Not used.
-:src: Pointer to a structure similar to pb_bytes_array_t.
-:returns: True on success, false on IO error.
-This function expects a pointer to a structure with a *size_t* field at start, and a variable sized byte array after it. The platform-specific field offset is inferred from *pb_bytes_array_t*, which has a byte array of size 1.
-pb_enc_string
--------------
-Field encoder for PB_LTYPE_STRING. Determines size of string with strlen() and then calls `pb_encode_string`_. ::
- bool pb_enc_string(pb_ostream_t *stream, const pb_field_t *field, const void *src);
-:stream: Output stream to write to.
-:field: Not used.
-:src: Pointer to a null-terminated string.
-:returns: True on success, false on IO error.
-
-pb_enc_submessage
------------------
-Field encoder for PB_LTYPE_SUBMESSAGE. Calls `pb_encode`_ to perform the actual encoding. ::
- bool pb_enc_submessage(pb_ostream_t *stream, const pb_field_t *field, const void *src);
-:stream: Output stream to write to.
-:field: Field description structure. The *ptr* field must be a pointer to a field description array for the submessage.
-:src: Pointer to the structure where submessage data is.
-:returns: True on success, false on IO errors, pb_encode errors or if submessage size changes between calls.
-In Protocol Buffers format, the submessage size must be written before the submessage contents. Therefore, this function has to encode the submessage twice in order to know the size beforehand.
-If the submessage contains callback fields, the callback function might misbehave and write out a different amount of data on the second call. This situation is recognized and *false* is returned, but it is up to the caller to ensure that the receiver of the message does not interpret it as valid data.
pb_decode.h
===========
End of file is signalled by *stream->bytes_left* being zero after pb_read returns false.
-pb_decode_varint
+pb_decode
+---------
+Read and decode all fields of a structure. Reads until EOF on input stream. ::
+
+ bool pb_decode(pb_istream_t *stream, const pb_field_t fields[], void *dest_struct);
+
+:stream: Input stream to read from.
+:fields: A field description array. Usually autogenerated.
+:dest_struct: Pointer to structure where data will be stored.
+:returns: True on success, false on IO error, on detectable errors in field description, if a field encoder returns false or if a required field is missing.
+
+In Protocol Buffers binary format, EOF is only allowed between fields. If it happens anywhere else, pb_decode will return *false*. If pb_decode returns false, you cannot trust any of the data in the structure.
+
+In addition to EOF, the pb_decode implementation supports terminating a message with a 0 byte. This is compatible with the official Protocol Buffers because 0 is never a valid field tag.
+
+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
----------------
-Read and decode a varint_ encoded integer. ::
+Same as `pb_decode`_, except does not apply the default values to fields. ::
- bool pb_decode_varint(pb_istream_t *stream, uint64_t *dest);
+ bool pb_decode_noinit(pb_istream_t *stream, const pb_field_t fields[], void *dest_struct);
-:stream: Input stream to read from. 1-10 bytes will be read.
-:dest: Storage for the decoded integer. Value is undefined on error.
-:returns: True on success, false if value exceeds uint64_t range or an IO error happens.
+(parameters are the same as for `pb_decode`_.)
+
+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
--------------
:stream: Input stream to read from.
:returns: True on success, false on IO error or length exceeding uint32_t.
-pb_decode
----------
-Read and decode all fields of a structure. Reads until EOF on input stream. ::
+pb_decode_tag
+-------------
+Decode the tag that comes before field in the protobuf encoding::
- bool pb_decode(pb_istream_t *stream, const pb_field_t fields[], void *dest_struct);
+ bool pb_decode_tag(pb_istream_t *stream, pb_wire_type_t *wire_type, int *tag, bool *eof);
:stream: Input stream to read from.
-:fields: A field description array. Usually autogenerated.
-:dest_struct: Pointer to structure where data will be stored.
-:returns: True on success, false on IO error, on detectable errors in field description, if a field encoder returns false or if a required field is missing.
+:wire_type: Pointer to variable where to store the wire type of the field.
+:tag: Pointer to variable where to store the tag of the field.
+:eof: Pointer to variable where to store end-of-file status.
+:returns: True on success, false on error or EOF.
-In Protocol Buffers binary format, EOF is only allowed between fields. If it happens anywhere else, pb_decode will return *false*. If pb_decode returns false, you cannot trust any of the data in the structure.
+When the message (stream) ends, this function will return false and set *eof* to true. On other
+errors, *eof* will be set to false.
-In addition to EOF, the pb_decode implementation supports terminating a message with a 0 byte. This is compatible with the official Protocol Buffers because 0 is never a valid field tag.
+pb_skip_field
+-------------
+Remove the data for a field from the stream, without actually decoding it::
-For optional fields, this function applies the default value and sets *has_<field>* to false if the field is not present.
+ bool pb_skip_field(pb_istream_t *stream, pb_wire_type_t wire_type);
-Because of memory concerns, the detection of missing required fields is not perfect if the structure contains more than 32 fields.
+:stream: Input stream to read from.
+:wire_type: Type of field to skip.
+:returns: True on success, false on IO error.
-.. sidebar:: Field decoders
+.. sidebar:: Decoding fields manually
- The functions with names beginning with *pb_dec_* are called field decoders. Each PB_LTYPE has an own field decoder, which handles translating from Protocol Buffers data to C data.
+ The functions with names beginning with *pb_decode_* 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_decode`_ will call your callback function repeatedly, which can then store the values into e.g. filesystem in the order received in.
- Each field decoder reads and decodes a single value. For arrays, the decoder is called repeatedly.
+ For decoding numeric (including enumerated and boolean) values, use `pb_decode_varint`_, `pb_decode_svarint`_, `pb_decode_fixed32`_ and `pb_decode_fixed64`_. They take a pointer to a 32- or 64-bit C variable, which you may then cast to smaller datatype for storage.
- You can use the decoders from your callbacks. Just be aware that the pb_field_t passed to the callback is not directly compatible with most of the field decoders. Instead, you must create a new pb_field_t structure and set the data_size according to the data type you pass to *dest.
+ For decoding strings and bytes fields, the length has already been decoded. You can therefore check the total length in *stream->bytes_left* and read the data using `pb_read`_.
-pb_dec_varint
--------------
-Field decoder for PB_LTYPE_VARINT. ::
+ Finally, for decoding submessages in a callback, simply use `pb_decode`_ and pass it the *SubMessage_fields* descriptor array.
- bool pb_dec_varint(pb_istream_t *stream, const pb_field_t *field, void *dest)
+pb_decode_varint
+----------------
+Read and decode a varint_ encoded integer. ::
-:stream: Input stream to read from. 1-10 bytes will be read.
-:field: Field description structure. Only *field->data_size* matters.
-:dest: Pointer to destination integer. Must have size of *field->data_size* bytes.
-:returns: True on success, false on IO errors or if `pb_decode_varint`_ fails.
+ bool pb_decode_varint(pb_istream_t *stream, uint64_t *dest);
-This function first calls `pb_decode_varint`_. It then copies the first bytes of the 64-bit result value to *dest*, or on big endian architectures, the last bytes.
+:stream: Input stream to read from. 1-10 bytes will be read.
+:dest: Storage for the decoded integer. Value is undefined on error.
+:returns: True on success, false if value exceeds uint64_t range or an IO error happens.
-pb_dec_svarint
---------------
-Field decoder for PB_LTYPE_SVARINT. Similar to `pb_dec_varint`_, except that it performs zigzag-decoding on the value. ::
+pb_decode_svarint
+-----------------
+Similar to `pb_decode_varint`_, except that it performs zigzag-decoding on the value. This corresponds to the Protocol Buffers *sint32* and *sint64* datatypes. ::
- bool pb_dec_svarint(pb_istream_t *stream, const pb_field_t *field, void *dest);
+ bool pb_decode_svarint(pb_istream_t *stream, int64_t *dest);
-(parameters are the same as `pb_dec_varint`_)
+(parameters are the same as `pb_decode_varint`_)
-pb_dec_fixed32
---------------
-Field decoder for PB_LTYPE_FIXED32. ::
+pb_decode_fixed32
+-----------------
+Decode a *fixed32*, *sfixed32* or *float* value. ::
- bool pb_dec_fixed(pb_istream_t *stream, const pb_field_t *field, void *dest);
+ bool pb_decode_fixed32(pb_istream_t *stream, void *dest);
-:stream: Input stream to read from. 1-10 bytes will be read.
-:field: Not used.
-:dest: Pointer to destination integer. Must have size of *field->data_size* bytes.
-:returns: True on success, false on IO errors or if `pb_decode_varint`_ fails.
+:stream: Input stream to read from. 4 bytes will be read.
+:dest: Pointer to destination *int32_t*, *uint32_t* or *float*.
+:returns: True on success, false on IO errors.
This function reads 4 bytes from the input stream.
On big endian architectures, it then reverses the order of the bytes.
Finally, it writes the bytes to *dest*.
-pb_dec_fixed64
---------------
-Field decoder for PB_LTYPE_FIXED64. ::
+pb_decode_fixed64
+-----------------
+Decode a *fixed64*, *sfixed64* or *double* value. ::
bool pb_dec_fixed(pb_istream_t *stream, const pb_field_t *field, void *dest);
-Same as `pb_dec_fixed32`_, except this reads 8 bytes.
-
-pb_dec_bytes
-------------
-Field decoder for PB_LTYPE_BYTES. Reads a length-prefixed block of bytes. ::
-
- bool pb_dec_bytes(pb_istream_t *stream, const pb_field_t *field, void *dest);
-
-:stream: Input stream to read from.
-:field: Field description structure. Only *field->data_size* matters.
-:dest: Pointer to a structure similar to pb_bytes_array_t.
-:returns: True on success, false on IO error or if length exceeds the array size.
-
-This function expects a pointer to a structure with a *size_t* field at start, and a variable sized byte array after it. It will deduce the maximum size of the array from *field->data_size*.
+:stream: Input stream to read from. 8 bytes will be read.
+:field: Not used.
+:dest: Pointer to destination *int64_t*, *uint64_t* or *double*.
+:returns: True on success, false on IO errors.
-pb_dec_string
--------------
-Field decoder for PB_LTYPE_STRING. Reads a length-prefixed string. ::
+Same as `pb_decode_fixed32`_, except this reads 8 bytes.
- bool pb_dec_string(pb_istream_t *stream, const pb_field_t *field, void *dest);
+pb_make_string_substream
+------------------------
+Decode the length for a field with wire type *PB_WT_STRING* and create a substream for reading the data. ::
-:stream: Input stream to read from.
-:field: Field description structure. Only *field->data_size* matters.
-:dest: Pointer to a character array of size *field->data_size*.
-:returns: True on success, false on IO error or if length exceeds the array size.
+ bool pb_make_string_substream(pb_istream_t *stream, pb_istream_t *substream);
-This function null-terminates the string when successful. On error, the contents of the destination array is undefined.
+:stream: Original input stream to read the length and data from.
+:substream: New substream that has limited length. Filled in by the function.
+:returns: True on success, false if reading the length fails.
-pb_dec_submessage
------------------
-Field decoder for PB_LTYPE_SUBMESSAGE. Calls `pb_decode`_ to perform the actual decoding. ::
+This function uses `pb_decode_varint`_ to read an integer from the stream. This is interpreted as a number of bytes, and the substream is set up so that its `bytes_left` is initially the same as the length, and its callback function and state the same as the parent stream.
- bool pb_dec_submessage(pb_istream_t *stream, const pb_field_t *field, void *dest)
+pb_close_string_substream
+-------------------------
+Close the substream created with `pb_make_string_substream`_. ::
-:stream: Input stream to read from.
-:field: Field description structure. Only *field->ptr* matters.
-:dest: Pointer to the destination structure.
-:returns: True on success, false on IO error or if `pb_decode`_ fails.
+ void pb_close_string_substream(pb_istream_t *stream, pb_istream_t *substream);
-The *field->ptr* should be a pointer to *pb_field_t* array describing the submessage.
+:stream: Original input stream to read the length and data from.
+:substream: Substream to close
+This function copies back the state from the substream to the parent stream.
+It must be called after done with the substream.
Code Review / apps / agl-service-can-low-level.git / blobdiff