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 /***************************
16 * Main encoding functions *
17 ***************************/
19 /* Encode a single protocol buffers message from C structure into a stream.
20 * Returns true on success, false on any failure.
21 * The actual struct pointed to by src_struct must match the description in fields.
22 * All required fields in the struct are assumed to have been filled in.
27 * pb_ostream_t stream;
30 * stream = pb_ostream_from_buffer(buffer, sizeof(buffer));
31 * pb_encode(&stream, MyMessage_fields, &msg);
33 bool pb_encode(pb_ostream_t *stream, const pb_field_t fields[], const void *src_struct);
36 /**************************************
37 * Functions for manipulating streams *
38 **************************************/
40 /* Create an output stream for writing into a memory buffer.
41 * The number of bytes written can be found in stream.bytes_written after
42 * encoding the message.
44 * Alternatively, you can use a custom stream that writes directly to e.g.
45 * a file or a network socket.
47 pb_ostream_t pb_ostream_from_buffer(uint8_t *buf, size_t bufsize);
49 /* Pseudo-stream for measuring the size of a message without actually storing
54 * pb_ostream_t stream = PB_OSTREAM_SIZING;
55 * pb_encode(&stream, MyMessage_fields, &msg);
56 * printf("Message size is %d\n", stream.bytes_written);
59 #define PB_OSTREAM_SIZING {0,0,0,0,0}
61 #define PB_OSTREAM_SIZING {0,0,0,0}
64 /* Function to write into a pb_ostream_t stream. You can use this if you need
65 * to append or prepend some custom headers to the message.
67 bool pb_write(pb_ostream_t *stream, const uint8_t *buf, size_t count);
69 /* Structure for defining custom output streams. You will need to provide
70 * a callback function to write the bytes to your storage, which can be
71 * for example a file or a network socket.
73 * The callback must conform to these rules:
75 * 1) Return false on IO errors. This will cause encoding to abort.
76 * 2) You can use state to store your own data (e.g. buffer pointer).
77 * 3) pb_write will update bytes_written after your callback runs.
78 * 4) Substreams will modify max_size and bytes_written. Don't use them
79 * to calculate any pointers.
84 /* Callback pointer is not used in buffer-only configuration.
85 * Having an int pointer here allows binary compatibility but
86 * gives an error if someone tries to assign callback function.
87 * Also, NULL pointer marks a 'sizing stream' that does not
92 bool (*callback)(pb_ostream_t *stream, const uint8_t *buf, size_t count);
94 void *state; /* Free field for use by callback implementation. */
95 size_t max_size; /* Limit number of output bytes written (or use SIZE_MAX). */
96 size_t bytes_written; /* Number of bytes written so far. */
104 /************************************************
105 * Helper functions for writing field callbacks *
106 ************************************************/
108 /* Encode field header based on type and field number defined in the field
109 * structure. Call this from the callback before writing out field contents. */
110 bool pb_encode_tag_for_field(pb_ostream_t *stream, const pb_field_t *field);
112 /* Encode field header by manually specifing wire type. You need to use this
113 * if you want to write out packed arrays from a callback field. */
114 bool pb_encode_tag(pb_ostream_t *stream, pb_wire_type_t wiretype, uint32_t field_number);
116 /* Encode an integer in the varint format.
117 * This works for bool, enum, int32, int64, uint32 and uint64 field types. */
118 bool pb_encode_varint(pb_ostream_t *stream, uint64_t value);
120 /* Encode an integer in the zig-zagged svarint format.
121 * This works for sint32 and sint64. */
122 bool pb_encode_svarint(pb_ostream_t *stream, int64_t value);
124 /* Encode a string or bytes type field. For strings, pass strlen(s) as size. */
125 bool pb_encode_string(pb_ostream_t *stream, const uint8_t *buffer, size_t size);
127 /* Encode a fixed32, sfixed32 or float value.
128 * You need to pass a pointer to a 4-byte wide C variable. */
129 bool pb_encode_fixed32(pb_ostream_t *stream, const void *value);
131 /* Encode a fixed64, sfixed64 or double value.
132 * You need to pass a pointer to a 8-byte wide C variable. */
133 bool pb_encode_fixed64(pb_ostream_t *stream, const void *value);
135 /* Encode a submessage field.
136 * You need to pass the pb_field_t array and pointer to struct, just like
137 * with pb_encode(). This internally encodes the submessage twice, first to
138 * calculate message size and then to actually write it out.
140 bool pb_encode_submessage(pb_ostream_t *stream, const pb_field_t fields[], const void *src_struct);
143 /*******************************
144 * Internal / legacy functions *
145 *******************************/
147 #ifdef NANOPB_INTERNALS
148 bool pb_enc_varint(pb_ostream_t *stream, const pb_field_t *field, const void *src);
149 bool pb_enc_svarint(pb_ostream_t *stream, const pb_field_t *field, const void *src);
150 bool pb_enc_fixed32(pb_ostream_t *stream, const pb_field_t *field, const void *src);
151 bool pb_enc_fixed64(pb_ostream_t *stream, const pb_field_t *field, const void *src);
152 bool pb_enc_bytes(pb_ostream_t *stream, const pb_field_t *field, const void *src);
153 bool pb_enc_string(pb_ostream_t *stream, const pb_field_t *field, const void *src);
156 /* This function is not recommended for new programs. Use pb_encode_submessage()
157 * instead, it has the same functionality with a less confusing interface. */
158 bool pb_enc_submessage(pb_ostream_t *stream, const pb_field_t *field, const void *src);