/* 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, 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 /* 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: * * 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. */ 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 pb_byte_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; /* 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); /* Same as pb_encode, but appends a null byte to the message for termination. * NOTE: This behaviour is not supported in most other protobuf implementations, so pb_encode_delimited() * is a better option for compatibility. */ bool pb_encode_nullterminated(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(pb_byte_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 pb_byte_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 specifying 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. * This works for bool, enum, int32, int64, uint32 and uint64 field types. */ #ifndef PB_WITHOUT_64BIT bool pb_encode_varint(pb_ostream_t *stream, uint64_t value); #else bool pb_encode_varint(pb_ostream_t *stream, uint32_t value); #endif /* Encode an integer in the zig-zagged svarint format. * This works for sint32 and sint64. */ #ifndef PB_WITHOUT_64BIT bool pb_encode_svarint(pb_ostream_t *stream, int64_t value); #else bool pb_encode_svarint(pb_ostream_t *stream, int32_t value); #endif /* Encode a string or bytes type field. For strings, pass strlen(s) as size. */ bool pb_encode_string(pb_ostream_t *stream, const pb_byte_t *buffer, size_t size); /* Encode a fixed32, sfixed32 or float value. * You need to pass a pointer to a 4-byte wide C variable. */ bool pb_encode_fixed32(pb_ostream_t *stream, const void *value); #ifndef PB_WITHOUT_64BIT /* Encode a fixed64, sfixed64 or double value. * You need to pass a pointer to a 8-byte wide C variable. */ bool pb_encode_fixed64(pb_ostream_t *stream, const void *value); #endif /* 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. */ bool pb_encode_submessage(pb_ostream_t *stream, const pb_field_t fields[], const void *src_struct); #ifdef __cplusplus } /* extern "C" */ #endif #endif