X-Git-Url: https://gerrit.automotivelinux.org/gerrit/gitweb?a=blobdiff_plain;f=pb_encode.h;h=e992c8dca18a1a0dad29ad1b6450f95e83ceb501;hb=7c00b90910d4e14e23e027eb951e6f2a8dcfae29;hp=773b7178c7a91d29e25ffc8b39754b1be871e9c9;hpb=a968233777e0781cfd3dd7b9566b631dc576fed1;p=apps%2Fagl-service-can-low-level.git diff --git a/pb_encode.h b/pb_encode.h index 773b7178..e992c8dc 100644 --- a/pb_encode.h +++ b/pb_encode.h @@ -1,35 +1,30 @@ -#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. */ +#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. @@ -42,42 +37,88 @@ struct _pb_ostream_t #else bool (*callback)(pb_ostream_t *stream, const uint8_t *buf, size_t count); #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; + 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 }; +/*************************** + * Main encoding functions * + ***************************/ + +/* 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); + +/* 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 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); -bool pb_write(pb_ostream_t *stream, const uint8_t *buf, size_t count); -/* Stream type for use in computing message sizes */ +/* 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 -/* Encode struct to given output 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. +/* 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_encode(pb_ostream_t *stream, const pb_field_t fields[], const void *src_struct); +bool pb_write(pb_ostream_t *stream, const uint8_t *buf, size_t count); -/* --- Helper functions --- - * You may want to use these from your caller or callbacks. - */ -/* Encode field header based on LTYPE and field number defined in the field structure. - * Call this from the callback before writing out field contents. */ +/************************************************ + * 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. @@ -100,29 +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