Diff: pb_encode.h

Revision:

0:c7beea49fc91

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/pb_encode.h	Tue Feb 19 20:03:29 2013 +0000
@@ -0,0 +1,120 @@
+#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"
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+/* 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 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_t
+{
+#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 uint8_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;
+};
+
+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.
+ */
+
+/* Encode field header based on LTYPE 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 specifing 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. */
+bool pb_encode_varint(pb_ostream_t *stream, uint64_t value);
+
+/* Encode an integer in the zig-zagged svarint format.
+ * This works for sint32 and sint64. */
+bool pb_encode_svarint(pb_ostream_t *stream, int64_t value);
+
+/* Encode a string or bytes type field. For strings, pass strlen(s) as size. */
+bool pb_encode_string(pb_ostream_t *stream, const uint8_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);
+
+/* 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);
+
+/* 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);
+
+/* --- Internal functions ---
+ * These functions are not terribly useful for the average library user, but
+ * are exported to make the unit testing and extending nanopb easier.
+ */
+
+#ifdef NANOPB_INTERNALS
+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_fixed32(pb_ostream_t *stream, const pb_field_t *field, const void *src);
+bool pb_enc_fixed64(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);
+#endif
+
+/* This function is not recommended for new programs. Use pb_encode_submessage()
+ * instead, it has the same functionality with a less confusing interface. */
+bool pb_enc_submessage(pb_ostream_t *stream, const pb_field_t *field, const void *src);
+
+#ifdef __cplusplus
+} /* extern "C" */
+#endif
+
+#endif