Expanding the tests to better cover decoding from memory buffer.

[apps/agl-service-can-low-level.git] / pb_decode.h

diff --git a/pb_decode.h b/pb_decode.h
index b71e20b..f12b190 100644 (file)
--- a/pb_decode.h
+++ b/pb_decode.h
@@ -1,55 +1,71 @@
 #ifndef _PB_DECODE_H_
 #define _PB_DECODE_H_
 
+/* pb_decode.h: Functions to decode protocol buffers. Depends on pb_decode.c.
+ * The main function is pb_decode. You will also need to create an input
+ * stream, which is easiest to do with pb_istream_t.
+ * 
+ * You also need structures and their corresponding pb_field_t descriptions.
+ * These are usually generated from .proto-files with a script.
+ */
+
 #include <stdbool.h>
 #include "pb.h"
 
-// Decode from stream to destination struct.
-// The actual struct pointed to by dest must match the description in fields.
-bool pb_decode(pb_istream_t *stream, const pb_field_t fields[], void *dest);
+/* Lightweight input stream.
+ * You can provide a callback function for reading or use
+ * pb_istream_from_buffer.
+ * 
+ * Rules for callback:
+ * 1) Return false on IO errors. This will cause decoding to abort.
+ * 
+ * 2) If buf is NULL, read but don't store bytes ("skip input").
+ * 
+ * 3) You can use state to store your own data (e.g. buffer pointer),
+ * and rely on pb_read to verify that no-body reads past bytes_left.
+ * 
+ * 4) Your callback may be used with substreams, in which case bytes_left
+ * is different than from the main stream. Don't use bytes_left to compute
+ * any pointers.
+ */
+struct _pb_istream_t
+{
+    bool (*callback)(pb_istream_t *stream, uint8_t *buf, size_t count);
+    void *state; /* Free field for use by callback implementation */
+    size_t bytes_left;
+};
+
+pb_istream_t pb_istream_from_buffer(uint8_t *buf, size_t bufsize);
+bool pb_read(pb_istream_t *stream, uint8_t *buf, size_t count);
+
+/* Decode from stream to destination struct.
+ * Returns true on success, false on any failure.
+ * The actual struct pointed to by dest must match the description in fields.
+ */
+bool pb_decode(pb_istream_t *stream, const pb_field_t fields[], void *dest_struct);
 
 /* --- Helper functions ---
- * You may want to use these from your callbacks.
+ * You may want to use these from your caller or callbacks.
  */
 
-bool pb_decode_varint32(pb_istream_t *stream, uint32_t *dest);
-bool pb_decode_varint64(pb_istream_t *stream, uint64_t *dest);
+bool pb_decode_varint(pb_istream_t *stream, uint64_t *dest);
 
 bool pb_skip_varint(pb_istream_t *stream);
 bool pb_skip_string(pb_istream_t *stream);
 
 /* --- Field decoders ---
  * Each decoder takes stream and field description, and a pointer to the field
- * in the destination struct (dest = struct_addr + field->offset).
+ * in the destination struct (dest = struct_addr + field->data_offset).
+ * For arrays, these functions are called repeatedly.
  */
 
-// Integer types.
-bool pb_dec_uint32(pb_istream_t *stream, const pb_field_t *field, void *dest);
-bool pb_dec_sint32(pb_istream_t *stream, const pb_field_t *field, void *dest);
+bool pb_dec_varint(pb_istream_t *stream, const pb_field_t *field, void *dest);
+bool pb_dec_svarint(pb_istream_t *stream, const pb_field_t *field, void *dest);
 bool pb_dec_fixed32(pb_istream_t *stream, const pb_field_t *field, void *dest);
-bool pb_dec_uint64(pb_istream_t *stream, const pb_field_t *field, void *dest);
-bool pb_dec_sint64(pb_istream_t *stream, const pb_field_t *field, void *dest);
 bool pb_dec_fixed64(pb_istream_t *stream, const pb_field_t *field, void *dest);
-bool pb_dec_bool(pb_istream_t *stream, const pb_field_t *field, void *dest);
 
-// Floating point types. Info is ignored.
-bool pb_dec_float(pb_istream_t *stream, const pb_field_t *field, void *dest);
-bool pb_dec_double(pb_istream_t *stream, const pb_field_t *field, void *dest);
-
-// Byte array. Dest is pointer to 
 bool pb_dec_bytes(pb_istream_t *stream, const pb_field_t *field, void *dest);
-
-// Null-terminated string.
 bool pb_dec_string(pb_istream_t *stream, const pb_field_t *field, void *dest);
-
-// Use callback. Dest is pointer to pb_callback_t struct.
 bool pb_dec_submessage(pb_istream_t *stream, const pb_field_t *field, void *dest);
 
-typedef bool (*pb_decoder_t)(pb_istream_t *stream, const pb_field_t *field, void *dest);
-
-/* --- Function pointers to field decoders ---
- * Order in the array must match pb_action_t numbering.
- */
-const pb_decoder_t PB_DECODERS[PB_LAST_ACT];
-
 #endif