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diff --git a/CAN-binder/libs/nanopb/docs/reference.rst b/CAN-binder/libs/nanopb/docs/reference.rst deleted file mode 100644 index e59a0c9..0000000 --- a/CAN-binder/libs/nanopb/docs/reference.rst +++ /dev/null @@ -1,770 +0,0 @@ -===================== -Nanopb: API reference -===================== - -.. include :: menu.rst - -.. 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. -anonymous_oneof Generate 'oneof' fields as anonymous unions. -fixed_length Generate 'bytes' fields with constant length. -============================ ================================================ - -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 -==== - -pb_byte_t ---------- -Type used for storing byte-sized data, such as raw binary input and bytes-type fields. :: - - typedef uint_least8_t pb_byte_t; - -For most platforms this is equivalent to `uint8_t`. Some platforms however do not support -8-bit variables, and on those platforms 16 or 32 bits need to be used for each byte. - -pb_type_t ---------- -Type used to store the type of each field, to control the encoder/decoder behaviour. :: - - typedef uint_least8_t pb_type_t; - -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_UVARINT 0x01 Unsigned integer. -PB_LTYPE_SVARINT 0x02 Integer, zigzag encoded. -PB_LTYPE_FIXED32 0x03 32-bit integer or floating point. -PB_LTYPE_FIXED64 0x04 64-bit integer or floating point. -PB_LTYPE_BYTES 0x05 Structure with *size_t* field and byte array. -PB_LTYPE_STRING 0x06 Null-terminated string. -PB_LTYPE_SUBMESSAGE 0x07 Submessage structure. -PB_LTYPE_EXTENSION 0x08 Point to *pb_extension_t*. -PB_LTYPE_FIXED_LENGTH_BYTES 0x09 Inline *pb_byte_t* array of fixed size. -=========================== ===== ================================================ - -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. - (Unless it is a callback) -PB_HTYPE_REPEATED 0x20 A repeated field with preallocated array. - Separate *<field>_count* for number of items. - (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. :: - - typedef struct pb_field_s pb_field_t; - struct pb_field_s { - pb_size_t tag; - pb_type_t type; - pb_size_t data_offset; - pb_ssize_t size_offset; - pb_size_t data_size; - pb_size_t array_size; - const void *ptr; - } pb_packed; - -:tag: Tag number of the field or 0 to terminate a list of fields. -: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 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 ----------------- -An byte array with a field for storing the length:: - - typedef struct { - pb_size_t size; - pb_byte_t bytes[1]; - } pb_bytes_array_t; - -In an actual array, the length of *bytes* may be different. - -pb_callback_t -------------- -Part of a message structure, for fields with type PB_HTYPE_CALLBACK:: - - 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, void * const *arg); - } funcs; - - void *arg; - }; - -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_wire_type_t --------------- -Protocol Buffers wire types. These are used with `pb_encode_tag`_. :: - - typedef enum { - PB_WT_VARINT = 0, - PB_WT_64BIT = 1, - PB_WT_STRING = 2, - 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; - bool found; - } 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*. -:found: Decoder sets this to true if the extension was found. - -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 -=========== - -pb_ostream_from_buffer ----------------------- -Constructs an output stream for writing into a memory buffer. This is just a helper function, it doesn't do anything you couldn't do yourself in a callback function. It uses an internal callback that stores the pointer in stream *state* field. :: - - pb_ostream_t pb_ostream_from_buffer(pb_byte_t *buf, size_t bufsize); - -:buf: Memory buffer to write into. -:bufsize: Maximum number of bytes to write. -:returns: An output stream. - -After writing, you can check *stream.bytes_written* to find out how much valid data there is in the buffer. - -pb_write --------- -Writes data to an output stream. Always use this function, instead of trying to call stream callback manually. :: - - bool pb_write(pb_ostream_t *stream, const pb_byte_t *buf, size_t count); - -:stream: Output stream to write to. -:buf: Pointer to buffer with the data to be written. -:count: Number of bytes to write. -:returns: True on success, false if maximum length is exceeded or an IO error happens. - -If an error happens, *bytes_written* is not incremented. Depending on the callback used, calling pb_write again after it has failed once may be dangerous. Nanopb itself never does this, instead it returns the error to user application. The builtin pb_ostream_from_buffer is safe to call again after failed write. - -pb_encode ---------- -Encodes the contents of a structure as a protocol buffers message and writes it to output stream. :: - - bool pb_encode(pb_ostream_t *stream, const pb_field_t fields[], const void *src_struct); - -:stream: Output stream to write to. -:fields: A field description array, usually autogenerated. -:src_struct: Pointer to the data that will be serialized. -:returns: True on success, false on IO error, on detectable errors in field description, or if a field encoder returns false. - -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. - - 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_get_encoded_size -------------------- -Calculates the length of the encoded message. :: - - bool pb_get_encoded_size(size_t *size, const pb_field_t fields[], const void *src_struct); - -:size: Calculated size of the encoded message. -:fields: A field description array, usually autogenerated. -:src_struct: Pointer to the data that will be serialized. -:returns: True on success, false on detectable errors in field description or if a field encoder returns false. - -pb_encode_tag -------------- -Starts a field in the Protocol Buffers binary format: encodes the field number and the wire type of the data. :: - - bool pb_encode_tag(pb_ostream_t *stream, pb_wire_type_t wiretype, uint32_t field_number); - -: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. You can get it from field->tag. -:returns: True on success, false on IO error. - -pb_encode_tag_for_field ------------------------ -Same as `pb_encode_tag`_, except takes the parameters from a *pb_field_t* structure. :: - - bool pb_encode_tag_for_field(pb_ostream_t *stream, const pb_field_t *field); - -:stream: Output stream to write to. 1-5 bytes will be written. -:field: Field description structure. Usually autogenerated. -:returns: True on success, false on IO error or unknown field type. - -This function only considers the LTYPE of the field. You can use it from your field callbacks, because the source generator writes correct LTYPE also for callback type fields. - -Wire type mapping is as follows: - -============================================= ============ -LTYPEs Wire type -============================================= ============ -VARINT, UVARINT, SVARINT PB_WT_VARINT -FIXED64 PB_WT_64BIT -STRING, BYTES, SUBMESSAGE, FIXED_LENGTH_BYTES PB_WT_STRING -FIXED32 PB_WT_32BIT -============================================= ============ - -pb_encode_varint ----------------- -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_varint(pb_ostream_t *stream, uint64_t value); - -: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. - -.. _varint: http://code.google.com/apis/protocolbuffers/docs/encoding.html#varints - -pb_encode_svarint ------------------ -Encodes a signed integer in the 'zig-zagged' format. Works for fields of type `sint32` and `sint64`:: - - bool pb_encode_svarint(pb_ostream_t *stream, int64_t value); - -(parameters are the same as for `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_encode_string(pb_ostream_t *stream, const pb_byte_t *buffer, size_t size); - -:stream: Output stream to write to. -: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_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_encode_fixed32(pb_ostream_t *stream, const void *value); - -: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. - -pb_encode_fixed64 ------------------ -Writes 8 bytes to stream and swaps bytes on big-endian architecture. Works for fields of type `fixed64`, `sfixed64` and `double`:: - - bool pb_encode_fixed64(pb_ostream_t *stream, const void *value); - -: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. - -pb_encode_submessage --------------------- -Encodes a submessage field, including the size header for it. Works for fields of any message type:: - - bool pb_encode_submessage(pb_ostream_t *stream, const pb_field_t fields[], const void *src_struct); - -: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. - -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 garbage will be written to the output before the problem is detected. - - - - - - - - - - - - -pb_decode.h -=========== - -pb_istream_from_buffer ----------------------- -Helper function for creating an input stream that reads data from a memory buffer. :: - - pb_istream_t pb_istream_from_buffer(const pb_byte_t *buf, size_t bufsize); - -:buf: Pointer to byte array to read from. -:bufsize: Size of the byte array. -:returns: An input stream ready to use. - -pb_read -------- -Read data from input stream. Always use this function, don't try to call the stream callback directly. :: - - bool pb_read(pb_istream_t *stream, pb_byte_t *buf, size_t count); - -:stream: Input stream to read from. -:buf: Buffer to store the data to, or NULL to just read data without storing it anywhere. -:count: Number of bytes to read. -:returns: True on success, false if *stream->bytes_left* is less than *count* or if an IO error occurs. - -End of file is signalled by *stream->bytes_left* being zero after pb_read returns false. - -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 ----------------- -Same as `pb_decode`_, except does not apply the default values to fields. :: - - bool pb_decode_noinit(pb_istream_t *stream, const pb_field_t fields[], void *dest_struct); - -(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 is stored. If NULL, function does nothing. - -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_decode_tag -------------- -Decode the tag that comes before field in the protobuf encoding:: - - bool pb_decode_tag(pb_istream_t *stream, pb_wire_type_t *wire_type, uint32_t *tag, bool *eof); - -:stream: Input stream to read from. -: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. - -When the message (stream) ends, this function will return false and set *eof* to true. On other -errors, *eof* will be set to false. - -pb_skip_field -------------- -Remove the data for a field from the stream, without actually decoding it:: - - bool pb_skip_field(pb_istream_t *stream, pb_wire_type_t wire_type); - -:stream: Input stream to read from. -:wire_type: Type of field to skip. -:returns: True on success, false on IO error. - -.. sidebar:: Decoding fields manually - - 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. - - 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. - - 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`_. - - Finally, for decoding submessages in a callback, simply use `pb_decode`_ and pass it the *SubMessage_fields* descriptor array. - -pb_decode_varint ----------------- -Read and decode a varint_ encoded integer. :: - - bool pb_decode_varint(pb_istream_t *stream, uint64_t *dest); - -: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_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_decode_svarint(pb_istream_t *stream, int64_t *dest); - -(parameters are the same as `pb_decode_varint`_) - -pb_decode_fixed32 ------------------ -Decode a *fixed32*, *sfixed32* or *float* value. :: - - bool pb_decode_fixed32(pb_istream_t *stream, void *dest); - -: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_decode_fixed64 ------------------ -Decode a *fixed64*, *sfixed64* or *double* value. :: - - bool pb_decode_fixed64(pb_istream_t *stream, void *dest); - -:stream: Input stream to read from. 8 bytes will be read. -:dest: Pointer to destination *int64_t*, *uint64_t* or *double*. -:returns: True on success, false on IO errors. - -Same as `pb_decode_fixed32`_, except this reads 8 bytes. - -pb_make_string_substream ------------------------- -Decode the length for a field with wire type *PB_WT_STRING* and create a substream for reading the data. :: - - bool pb_make_string_substream(pb_istream_t *stream, pb_istream_t *substream); - -: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. - -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. - -pb_close_string_substream -------------------------- -Close the substream created with `pb_make_string_substream`_. :: - - void pb_close_string_substream(pb_istream_t *stream, pb_istream_t *substream); - -: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. |