X-Git-Url: https://gerrit.automotivelinux.org/gerrit/gitweb?a=blobdiff_plain;f=pb_encode.h;h=e992c8dca18a1a0dad29ad1b6450f95e83ceb501;hb=b836ac29dd212f173b0607c826d23b3e3da3d61a;hp=85a829739c923c13bd39407d39ed3637334d5a91;hpb=3aaa4ad8c290af87d9bb9e24447f9cd6f9a79eab;p=apps%2Fagl-service-can-low-level.git diff --git a/pb_encode.h b/pb_encode.h index 85a82973..e992c8dc 100644 --- a/pb_encode.h +++ b/pb_encode.h @@ -1,63 +1,124 @@ -#ifndef _PB_ENCODE_H_ -#define _PB_ENCODE_H_ - /* pb_encode.h: Functions to encode protocol buffers. Depends on pb_encode.c. - * The main function is pb_encode. You also need an output stream, structures - * and their field descriptions (just like with pb_decode). + * The main function is pb_encode. You also need an output stream, and the + * field descriptions created by nanopb_generator.py. */ -#include +#ifndef PB_ENCODE_H_INCLUDED +#define PB_ENCODE_H_INCLUDED + #include "pb.h" #ifdef __cplusplus extern "C" { #endif -/* Lightweight output stream. - * You can provide callback for writing or use pb_ostream_from_buffer. - * - * Alternatively, callback can be NULL in which case the stream will just - * count the number of bytes that would have been written. In this case - * max_size is not checked. +/* Structure for defining custom output streams. You will need to provide + * a callback function to write the bytes to your storage, which can be + * for example a file or a network socket. + * + * The callback must conform to these rules: * - * Rules for callback: * 1) Return false on IO errors. This will cause encoding to abort. - * * 2) You can use state to store your own data (e.g. buffer pointer). - * * 3) pb_write will update bytes_written after your callback runs. - * - * 4) Substreams will modify max_size and bytes_written. Don't use them to - * calculate any pointers. + * 4) Substreams will modify max_size and bytes_written. Don't use them + * to calculate any pointers. */ -struct _pb_ostream_t +struct pb_ostream_s { +#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. + * Also, NULL pointer marks a 'sizing stream' that does not + * write anything. + */ + int *callback; +#else bool (*callback)(pb_ostream_t *stream, const uint8_t *buf, size_t count); - void *state; /* Free field for use by callback implementation */ - size_t max_size; /* Limit number of output bytes written (or use SIZE_MAX). */ - size_t bytes_written; +#endif + void *state; /* Free field for use by callback implementation. */ + size_t max_size; /* Limit number of output bytes written (or use SIZE_MAX). */ + size_t bytes_written; /* Number of bytes written so far. */ + +#ifndef PB_NO_ERRMSG + const char *errmsg; +#endif }; -pb_ostream_t pb_ostream_from_buffer(uint8_t *buf, size_t bufsize); -bool pb_write(pb_ostream_t *stream, const uint8_t *buf, size_t count); +/*************************** + * Main encoding functions * + ***************************/ -/* Encode struct to given output stream. +/* Encode a single protocol buffers message from C structure into a stream. * Returns true on success, false on any failure. * The actual struct pointed to by src_struct must match the description in fields. * All required fields in the struct are assumed to have been filled in. + * + * Example usage: + * MyMessage msg = {}; + * uint8_t buffer[64]; + * pb_ostream_t stream; + * + * msg.field1 = 42; + * stream = pb_ostream_from_buffer(buffer, sizeof(buffer)); + * pb_encode(&stream, MyMessage_fields, &msg); */ bool pb_encode(pb_ostream_t *stream, const pb_field_t fields[], const void *src_struct); -/* --- Helper functions --- - * You may want to use these from your caller or callbacks. +/* Same as pb_encode, but prepends the length of the message as a varint. + * Corresponds to writeDelimitedTo() in Google's protobuf API. */ +bool pb_encode_delimited(pb_ostream_t *stream, const pb_field_t fields[], const void *src_struct); -/* Encode field header based on LTYPE and field number defined in the field structure. - * Call this from the callback before writing out field contents. */ +/* Encode the message to get the size of the encoded data, but do not store + * the data. */ +bool pb_get_encoded_size(size_t *size, const pb_field_t fields[], const void *src_struct); + +/************************************** + * Functions for manipulating streams * + **************************************/ + +/* Create an output stream for writing into a memory buffer. + * The number of bytes written can be found in stream.bytes_written after + * encoding the message. + * + * Alternatively, you can use a custom stream that writes directly to e.g. + * a file or a network socket. + */ +pb_ostream_t pb_ostream_from_buffer(uint8_t *buf, size_t bufsize); + +/* Pseudo-stream for measuring the size of a message without actually storing + * the encoded data. + * + * Example usage: + * MyMessage msg = {}; + * pb_ostream_t stream = PB_OSTREAM_SIZING; + * pb_encode(&stream, MyMessage_fields, &msg); + * printf("Message size is %d\n", stream.bytes_written); + */ +#ifndef PB_NO_ERRMSG +#define PB_OSTREAM_SIZING {0,0,0,0,0} +#else +#define PB_OSTREAM_SIZING {0,0,0,0} +#endif + +/* Function to write into a pb_ostream_t stream. You can use this if you need + * to append or prepend some custom headers to the message. + */ +bool pb_write(pb_ostream_t *stream, const uint8_t *buf, size_t count); + + +/************************************************ + * Helper functions for writing field callbacks * + ************************************************/ + +/* Encode field header based on type and field number defined in the field + * structure. Call this from the callback before writing out field contents. */ bool pb_encode_tag_for_field(pb_ostream_t *stream, const pb_field_t *field); -/* Encode field header by manually specifing wire type. You need to use this if - * you want to write out packed arrays from a callback field. */ +/* Encode field header by manually specifing wire type. You need to use this + * if you want to write out packed arrays from a callback field. */ bool pb_encode_tag(pb_ostream_t *stream, pb_wire_type_t wiretype, uint32_t field_number); /* Encode an integer in the varint format. @@ -80,29 +141,12 @@ bool pb_encode_fixed32(pb_ostream_t *stream, const void *value); bool pb_encode_fixed64(pb_ostream_t *stream, const void *value); /* Encode a submessage field. - * You need to pass the pb_field_t array and pointer to struct, just like with pb_encode(). - * This internally encodes the submessage twice, first to calculate message size and then to actually write it out. + * You need to pass the pb_field_t array and pointer to struct, just like + * with pb_encode(). This internally encodes the submessage twice, first to + * calculate message size and then to actually write it out. */ bool pb_encode_submessage(pb_ostream_t *stream, const pb_field_t fields[], const void *src_struct); -/* --- 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. - */ - -#ifdef NANOPB_INTERNALS -bool pb_enc_varint(pb_ostream_t *stream, const pb_field_t *field, const void *src); -bool pb_enc_svarint(pb_ostream_t *stream, const pb_field_t *field, const void *src); -bool pb_enc_fixed32(pb_ostream_t *stream, const pb_field_t *field, const void *src); -bool pb_enc_fixed64(pb_ostream_t *stream, const pb_field_t *field, const void *src); -bool pb_enc_bytes(pb_ostream_t *stream, const pb_field_t *field, const void *src); -bool pb_enc_string(pb_ostream_t *stream, const pb_field_t *field, const void *src); -#endif - -/* This function is not recommended for new programs. Use pb_encode_submessage() - * instead, it has the same functionality with a less confusing interface. */ -bool pb_enc_submessage(pb_ostream_t *stream, const pb_field_t *field, const void *src); - #ifdef __cplusplus } /* extern "C" */ #endif