X-Git-Url: https://gerrit.automotivelinux.org/gerrit/gitweb?a=blobdiff_plain;f=pb_decode.h;h=85efa212e0999eb2c346293b8ebbbbec7b59c78e;hb=314460c2a518bdfc4e5dfb87992d907461a7c0e6;hp=35de0a2264318984304938494f217296e05fcfa7;hpb=4ba6a3027d7a5d8c17abeb031622389f8be234fe;p=apps%2Fagl-service-can-low-level.git diff --git a/pb_decode.h b/pb_decode.h index 35de0a22..85efa212 100644 --- a/pb_decode.h +++ b/pb_decode.h @@ -1,34 +1,77 @@ -#ifndef _PB_DECODE_H_ -#define _PB_DECODE_H_ - /* pb_decode.h: Functions to decode protocol buffers. Depends on pb_decode.c. - * The main function is pb_decode. You will also need to create an input - * stream, which is easiest to do with pb_istream_from_buffer(). - * - * You also need structures and their corresponding pb_field_t descriptions. - * These are usually generated from .proto-files with a script. + * The main function is pb_decode. You also need an input stream, and the + * field descriptions created by nanopb_generator.py. */ -#include +#ifndef _PB_DECODE_H_ +#define _PB_DECODE_H_ + #include "pb.h" #ifdef __cplusplus extern "C" { #endif -/* Lightweight input stream. - * You can provide a callback function for reading or use - * pb_istream_from_buffer. +/*************************** + * Main decoding functions * + ***************************/ + +/* Decode a single protocol buffers message from input stream into a C structure. + * Returns true on success, false on any failure. + * The actual struct pointed to by dest must match the description in fields. + * Callback fields of the destination structure must be initialized by caller. + * All other fields will be initialized by this function. + * + * Example usage: + * MyMessage msg = {}; + * uint8_t buffer[64]; + * pb_istream_t stream; + * + * // ... read some data into buffer ... + * + * stream = pb_istream_from_buffer(buffer, count); + * pb_decode(&stream, MyMessage_fields, &msg); + */ +bool pb_decode(pb_istream_t *stream, const pb_field_t fields[], void *dest_struct); + +/* Same as pb_decode, except does not initialize the destination structure + * to default values. This is slightly faster if you need no default values + * and just do memset(struct, 0, sizeof(struct)) yourself. + * + * This can also be used for 'merging' two messages, i.e. update only the + * fields that exist in the new message. + */ +bool pb_decode_noinit(pb_istream_t *stream, const pb_field_t fields[], void *dest_struct); + + +/************************************** + * Functions for manipulating streams * + **************************************/ + +/* Create an input stream for reading from a memory buffer. + * + * Alternatively, you can use a custom stream that reads directly from e.g. + * a file or a network socket. + */ +pb_istream_t pb_istream_from_buffer(uint8_t *buf, size_t bufsize); + +/* Function to read from a pb_istream_t. You can use this if you need to + * read some custom header data, or to read data in field callbacks. + */ +bool pb_read(pb_istream_t *stream, uint8_t *buf, size_t count); + +/* Structure for defining custom input streams. You will need to provide + * a callback function to read the bytes from your storage, which can be + * for example a file or a network socket. * - * Rules for callback: + * The callback must conform to these rules: + * * 1) Return false on IO errors. This will cause decoding to abort. - * * 2) You can use state to store your own data (e.g. buffer pointer), - * and rely on pb_read to verify that no-body reads past bytes_left. - * + * and rely on pb_read to verify that no-body reads past bytes_left. * 3) Your callback may be used with substreams, in which case bytes_left - * is different than from the main stream. Don't use bytes_left to compute - * any pointers. + * is different than from the main stream. Don't use bytes_left to compute + * any pointers. */ struct _pb_istream_t { @@ -50,24 +93,10 @@ struct _pb_istream_t #endif }; -pb_istream_t pb_istream_from_buffer(uint8_t *buf, size_t bufsize); -bool pb_read(pb_istream_t *stream, uint8_t *buf, size_t count); - -/* Decode from stream to destination struct. - * Returns true on success, false on any failure. - * The actual struct pointed to by dest must match the description in fields. - */ -bool pb_decode(pb_istream_t *stream, const pb_field_t fields[], void *dest_struct); - -/* Same as pb_decode, except does not initialize the destination structure - * to default values. This is slightly faster if you need no default values - * and just do memset(struct, 0, sizeof(struct)) yourself. - */ -bool pb_decode_noinit(pb_istream_t *stream, const pb_field_t fields[], void *dest_struct); -/* --- Helper functions --- - * You may want to use these from your caller or callbacks. - */ +/************************************************ + * Helper functions for writing field callbacks * + ************************************************/ /* Decode the tag for the next field in the stream. Gives the wire type and * field tag. At end of the message, returns false and sets eof to true. */ @@ -96,10 +125,10 @@ bool pb_decode_fixed64(pb_istream_t *stream, void *dest); bool pb_make_string_substream(pb_istream_t *stream, pb_istream_t *substream); void pb_close_string_substream(pb_istream_t *stream, pb_istream_t *substream); -/* --- Internal functions --- - * These functions are not terribly useful for the average library user, but - * are exported to make the unit testing and extending nanopb easier. - */ + +/******************************* + * Internal / legacy functions * + *******************************/ #ifdef NANOPB_INTERNALS bool pb_dec_varint(pb_istream_t *stream, const pb_field_t *field, void *dest);