Encoder

git-svn-id: https://svn.kapsi.fi/jpa/nanopb@951 e3a754e5-d11d-0410-8d38-ebb782a927b9

pb_encode.h

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+#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).
+ */
+
+#include <stdbool.h>
+#include "pb.h"
+
+/* 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.
+ *
+ * Rules for callback:
+ * 1) Return false on IO errors. This will cause decoding to abort.
+ * 
+ * 2) You can use state to store your own data (e.g. buffer pointer).
+ * 
+ * 3) pb_write will update bytes_written before your callback runs.
+ * 
+ * 4) Your callback will be always used with the same pb_ostream_t.
+ * There are no substreams when encoding.
+ */
+struct _pb_ostream_t
+{
+    bool (*callback)(pb_ostream_t *stream, const uint8_t *buf, size_t count);
+    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;
+};
+
+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);
+
+/* 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.
+ */
+bool pb_encode(pb_ostream_t *stream, const pb_field_t fields[], const void *src_struct);
+
+/* --- Helper functions ---
+ * You may want to use these from your caller or callbacks.
+ */
+
+bool pb_encode_varint(pb_ostream_t *stream, uint64_t value);
+bool pb_encode_tag(pb_ostream_t *stream, pb_wire_type_t wiretype, int field_number);
+bool pb_encode_tag_for_field(pb_ostream_t *stream, const pb_field_t *field);
+bool pb_encode_string(pb_ostream_t *stream, uint8_t *buffer, size_t size);
+
+/* --- Field encoders ---
+ * Each encoder writes the content for the field.
+ * The tag/wire type has been written already.
+ */
+
+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_fixed(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);
+bool pb_enc_submessage(pb_ostream_t *stream, const pb_field_t *field, const void *src);
+
+#endif