X-Git-Url: https://gerrit.automotivelinux.org/gerrit/gitweb?a=blobdiff_plain;f=pb_decode.h;h=85efa212e0999eb2c346293b8ebbbbec7b59c78e;hb=314460c2a518bdfc4e5dfb87992d907461a7c0e6;hp=7045c5d6736d4f8354b906f0ba6eb99fde2ba706;hpb=8524de39ce2e4c369ed1051c7ed2e4cd43ad321d;p=apps%2Fagl-service-can-low-level.git diff --git a/pb_decode.h b/pb_decode.h index 7045c5d6..85efa212 100644 --- a/pb_decode.h +++ b/pb_decode.h @@ -1,67 +1,136 @@ +/* pb_decode.h: Functions to decode protocol buffers. Depends on pb_decode.c. + * The main function is pb_decode. You also need an input stream, and the + * field descriptions created by nanopb_generator.py. + */ + #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_t. - * - * You also need structures and their corresponding pb_field_t descriptions. - * These are usually generated from .proto-files with a script. +#include "pb.h" + +#ifdef __cplusplus +extern "C" { +#endif + +/*************************** + * 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); -#include -#include "pb.h" +/* 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); -/* Lightweight input stream. - * You can provide a callback function for reading or use - * pb_istream_from_buffer. +/* 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) If buf is NULL, read but don't store bytes ("skip input"). - * - * 3) 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. - * - * 4) 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. + * 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. + * 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. */ struct _pb_istream_t { +#ifdef PB_BUFFER_ONLY + /* Callback pointer is not used in buffer-only configuration. + * Having an int pointer here allows binary compatibility but + * gives an error if someone tries to assign callback function. + */ + int *callback; +#else bool (*callback)(pb_istream_t *stream, uint8_t *buf, size_t count); +#endif + void *state; /* Free field for use by callback implementation */ size_t bytes_left; + +#ifndef PB_NO_ERRMSG + const char *errmsg; +#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); - -/* --- 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. */ bool pb_decode_tag(pb_istream_t *stream, pb_wire_type_t *wire_type, uint32_t *tag, bool *eof); + +/* Skip the field payload data, given the wire type. */ bool pb_skip_field(pb_istream_t *stream, pb_wire_type_t wire_type); +/* Decode an integer in the varint format. This works for bool, enum, int32, + * int64, uint32 and uint64 field types. */ bool pb_decode_varint(pb_istream_t *stream, uint64_t *dest); -bool pb_skip_varint(pb_istream_t *stream); -bool pb_skip_string(pb_istream_t *stream); +/* Decode an integer in the zig-zagged svarint format. This works for sint32 + * and sint64. */ +bool pb_decode_svarint(pb_istream_t *stream, int64_t *dest); -/* --- Field decoders --- - * Each decoder takes stream and field description, and a pointer to the field - * in the destination struct (dest = struct_addr + field->data_offset). - * For arrays, these functions are called repeatedly. - */ +/* Decode a fixed32, sfixed32 or float value. You need to pass a pointer to + * a 4-byte wide C variable. */ +bool pb_decode_fixed32(pb_istream_t *stream, void *dest); + +/* Decode a fixed64, sfixed64 or double value. You need to pass a pointer to + * a 8-byte wide C variable. */ +bool pb_decode_fixed64(pb_istream_t *stream, void *dest); + +/* Make a limited-length substream for reading a PB_WT_STRING field. */ +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 / legacy functions * + *******************************/ +#ifdef NANOPB_INTERNALS bool pb_dec_varint(pb_istream_t *stream, const pb_field_t *field, void *dest); bool pb_dec_svarint(pb_istream_t *stream, const pb_field_t *field, void *dest); bool pb_dec_fixed32(pb_istream_t *stream, const pb_field_t *field, void *dest); @@ -71,4 +140,12 @@ bool pb_dec_bytes(pb_istream_t *stream, const pb_field_t *field, void *dest); bool pb_dec_string(pb_istream_t *stream, const pb_field_t *field, void *dest); bool pb_dec_submessage(pb_istream_t *stream, const pb_field_t *field, void *dest); +bool pb_skip_varint(pb_istream_t *stream); +bool pb_skip_string(pb_istream_t *stream); +#endif + +#ifdef __cplusplus +} /* extern "C" */ +#endif + #endif