1 /* pb_encode.h: Functions to encode protocol buffers. Depends on pb_encode.c.
2 * The main function is pb_encode. You also need an output stream, and the
3 * field descriptions created by nanopb_generator.py.
15 /* Structure for defining custom output streams. You will need to provide
16 * a callback function to write the bytes to your storage, which can be
17 * for example a file or a network socket.
19 * The callback must conform to these rules:
21 * 1) Return false on IO errors. This will cause encoding to abort.
22 * 2) You can use state to store your own data (e.g. buffer pointer).
23 * 3) pb_write will update bytes_written after your callback runs.
24 * 4) Substreams will modify max_size and bytes_written. Don't use them
25 * to calculate any pointers.
30 /* Callback pointer is not used in buffer-only configuration.
31 * Having an int pointer here allows binary compatibility but
32 * gives an error if someone tries to assign callback function.
33 * Also, NULL pointer marks a 'sizing stream' that does not
38 bool (*callback)(pb_ostream_t *stream, const uint8_t *buf, size_t count);
40 void *state; /* Free field for use by callback implementation. */
41 size_t max_size; /* Limit number of output bytes written (or use SIZE_MAX). */
42 size_t bytes_written; /* Number of bytes written so far. */
49 /***************************
50 * Main encoding functions *
51 ***************************/
53 /* Encode a single protocol buffers message from C structure into a stream.
54 * Returns true on success, false on any failure.
55 * The actual struct pointed to by src_struct must match the description in fields.
56 * All required fields in the struct are assumed to have been filled in.
61 * pb_ostream_t stream;
64 * stream = pb_ostream_from_buffer(buffer, sizeof(buffer));
65 * pb_encode(&stream, MyMessage_fields, &msg);
67 bool pb_encode(pb_ostream_t *stream, const pb_field_t fields[], const void *src_struct);
69 /* Same as pb_encode, but prepends the length of the message as a varint.
70 * Corresponds to writeDelimitedTo() in Google's protobuf API.
72 bool pb_encode_delimited(pb_ostream_t *stream, const pb_field_t fields[], const void *src_struct);
74 /**************************************
75 * Functions for manipulating streams *
76 **************************************/
78 /* Create an output stream for writing into a memory buffer.
79 * The number of bytes written can be found in stream.bytes_written after
80 * encoding the message.
82 * Alternatively, you can use a custom stream that writes directly to e.g.
83 * a file or a network socket.
85 pb_ostream_t pb_ostream_from_buffer(uint8_t *buf, size_t bufsize);
87 /* Pseudo-stream for measuring the size of a message without actually storing
92 * pb_ostream_t stream = PB_OSTREAM_SIZING;
93 * pb_encode(&stream, MyMessage_fields, &msg);
94 * printf("Message size is %d\n", stream.bytes_written);
97 #define PB_OSTREAM_SIZING {0,0,0,0,0}
99 #define PB_OSTREAM_SIZING {0,0,0,0}
102 /* Function to write into a pb_ostream_t stream. You can use this if you need
103 * to append or prepend some custom headers to the message.
105 bool pb_write(pb_ostream_t *stream, const uint8_t *buf, size_t count);
108 /************************************************
109 * Helper functions for writing field callbacks *
110 ************************************************/
112 /* Encode field header based on type and field number defined in the field
113 * structure. Call this from the callback before writing out field contents. */
114 bool pb_encode_tag_for_field(pb_ostream_t *stream, const pb_field_t *field);
116 /* Encode field header by manually specifing wire type. You need to use this
117 * if you want to write out packed arrays from a callback field. */
118 bool pb_encode_tag(pb_ostream_t *stream, pb_wire_type_t wiretype, uint32_t field_number);
120 /* Encode an integer in the varint format.
121 * This works for bool, enum, int32, int64, uint32 and uint64 field types. */
122 bool pb_encode_varint(pb_ostream_t *stream, uint64_t value);
124 /* Encode an integer in the zig-zagged svarint format.
125 * This works for sint32 and sint64. */
126 bool pb_encode_svarint(pb_ostream_t *stream, int64_t value);
128 /* Encode a string or bytes type field. For strings, pass strlen(s) as size. */
129 bool pb_encode_string(pb_ostream_t *stream, const uint8_t *buffer, size_t size);
131 /* Encode a fixed32, sfixed32 or float value.
132 * You need to pass a pointer to a 4-byte wide C variable. */
133 bool pb_encode_fixed32(pb_ostream_t *stream, const void *value);
135 /* Encode a fixed64, sfixed64 or double value.
136 * You need to pass a pointer to a 8-byte wide C variable. */
137 bool pb_encode_fixed64(pb_ostream_t *stream, const void *value);
139 /* Encode a submessage field.
140 * You need to pass the pb_field_t array and pointer to struct, just like
141 * with pb_encode(). This internally encodes the submessage twice, first to
142 * calculate message size and then to actually write it out.
144 bool pb_encode_submessage(pb_ostream_t *stream, const pb_field_t fields[], const void *src_struct);
147 /*******************************
148 * Internal / legacy functions *
149 *******************************/
151 #ifdef NANOPB_INTERNALS
152 bool pb_enc_varint(pb_ostream_t *stream, const pb_field_t *field, const void *src);
153 bool pb_enc_svarint(pb_ostream_t *stream, const pb_field_t *field, const void *src);
154 bool pb_enc_fixed32(pb_ostream_t *stream, const pb_field_t *field, const void *src);
155 bool pb_enc_fixed64(pb_ostream_t *stream, const pb_field_t *field, const void *src);
156 bool pb_enc_bytes(pb_ostream_t *stream, const pb_field_t *field, const void *src);
157 bool pb_enc_string(pb_ostream_t *stream, const pb_field_t *field, const void *src);
160 /* This function is not recommended for new programs. Use pb_encode_submessage()
161 * instead, it has the same functionality with a less confusing interface. */
162 bool pb_enc_submessage(pb_ostream_t *stream, const pb_field_t *field, const void *src);