pb_encode.h

00001 #ifndef _PB_ENCODE_H_
00002 #define _PB_ENCODE_H_
00003 
00004 /* pb_encode.h: Functions to encode protocol buffers. Depends on pb_encode.c.
00005  * The main function is pb_encode. You also need an output stream, structures
00006  * and their field descriptions (just like with pb_decode).
00007  */
00008 
00009 #include <stdbool.h>
00010 #include "pb.h"
00011 
00012 #ifdef __cplusplus
00013 extern "C" {
00014 #endif
00015 
00016 /* Lightweight output stream.
00017  * You can provide callback for writing or use pb_ostream_from_buffer.
00018  * 
00019  * Alternatively, callback can be NULL in which case the stream will just
00020  * count the number of bytes that would have been written. In this case
00021  * max_size is not checked.
00022  *
00023  * Rules for callback:
00024  * 1) Return false on IO errors. This will cause encoding to abort.
00025  * 
00026  * 2) You can use state to store your own data (e.g. buffer pointer).
00027  * 
00028  * 3) pb_write will update bytes_written after your callback runs.
00029  * 
00030  * 4) Substreams will modify max_size and bytes_written. Don't use them to
00031  * calculate any pointers.
00032  */
00033 struct _pb_ostream_t
00034 {
00035 #ifdef PB_BUFFER_ONLY
00036     /* Callback pointer is not used in buffer-only configuration.
00037      * Having an int pointer here allows binary compatibility but
00038      * gives an error if someone tries to assign callback function.
00039      * Also, NULL pointer marks a 'sizing stream' that does not
00040      * write anything.
00041      */
00042     int *callback;
00043 #else
00044     bool (*callback)(pb_ostream_t *stream, const uint8_t *buf, size_t count);
00045 #endif
00046     void *state; /* Free field for use by callback implementation */
00047     size_t max_size; /* Limit number of output bytes written (or use SIZE_MAX). */
00048     size_t bytes_written;
00049 };
00050 
00051 pb_ostream_t pb_ostream_from_buffer(uint8_t *buf, size_t bufsize);
00052 bool pb_write(pb_ostream_t *stream, const uint8_t *buf, size_t count);
00053 
00054 /* Encode struct to given output stream.
00055  * Returns true on success, false on any failure.
00056  * The actual struct pointed to by src_struct must match the description in fields.
00057  * All required fields in the struct are assumed to have been filled in.
00058  */
00059 bool pb_encode(pb_ostream_t *stream, const pb_field_t fields[], const void *src_struct);
00060 
00061 /* --- Helper functions ---
00062  * You may want to use these from your caller or callbacks.
00063  */
00064 
00065 /* Encode field header based on LTYPE and field number defined in the field structure.
00066  * Call this from the callback before writing out field contents. */
00067 bool pb_encode_tag_for_field(pb_ostream_t *stream, const pb_field_t *field);
00068 
00069 /* Encode field header by manually specifing wire type. You need to use this if
00070  * you want to write out packed arrays from a callback field. */
00071 bool pb_encode_tag(pb_ostream_t *stream, pb_wire_type_t wiretype, uint32_t field_number);
00072 
00073 /* Encode an integer in the varint format.
00074  * This works for bool, enum, int32, int64, uint32 and uint64 field types. */
00075 bool pb_encode_varint(pb_ostream_t *stream, uint64_t value);
00076 
00077 /* Encode an integer in the zig-zagged svarint format.
00078  * This works for sint32 and sint64. */
00079 bool pb_encode_svarint(pb_ostream_t *stream, int64_t value);
00080 
00081 /* Encode a string or bytes type field. For strings, pass strlen(s) as size. */
00082 bool pb_encode_string(pb_ostream_t *stream, const uint8_t *buffer, size_t size);
00083 
00084 /* Encode a fixed32, sfixed32 or float value.
00085  * You need to pass a pointer to a 4-byte wide C variable. */
00086 bool pb_encode_fixed32(pb_ostream_t *stream, const void *value);
00087 
00088 /* Encode a fixed64, sfixed64 or double value.
00089  * You need to pass a pointer to a 8-byte wide C variable. */
00090 bool pb_encode_fixed64(pb_ostream_t *stream, const void *value);
00091 
00092 /* Encode a submessage field.
00093  * You need to pass the pb_field_t array and pointer to struct, just like with pb_encode().
00094  * This internally encodes the submessage twice, first to calculate message size and then to actually write it out.
00095  */
00096 bool pb_encode_submessage(pb_ostream_t *stream, const pb_field_t fields[], const void *src_struct);
00097 
00098 /* --- Internal functions ---
00099  * These functions are not terribly useful for the average library user, but
00100  * are exported to make the unit testing and extending nanopb easier.
00101  */
00102 
00103 #ifdef NANOPB_INTERNALS
00104 bool pb_enc_varint(pb_ostream_t *stream, const pb_field_t *field, const void *src);
00105 bool pb_enc_svarint(pb_ostream_t *stream, const pb_field_t *field, const void *src);
00106 bool pb_enc_fixed32(pb_ostream_t *stream, const pb_field_t *field, const void *src);
00107 bool pb_enc_fixed64(pb_ostream_t *stream, const pb_field_t *field, const void *src);
00108 bool pb_enc_bytes(pb_ostream_t *stream, const pb_field_t *field, const void *src);
00109 bool pb_enc_string(pb_ostream_t *stream, const pb_field_t *field, const void *src);
00110 #endif
00111 
00112 /* This function is not recommended for new programs. Use pb_encode_submessage()
00113  * instead, it has the same functionality with a less confusing interface. */
00114 bool pb_enc_submessage(pb_ostream_t *stream, const pb_field_t *field, const void *src);
00115 
00116 #ifdef __cplusplus
00117 } /* extern "C" */
00118 #endif
00119 
00120 #endif