shithub: opusfile

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Abstract position indicator tracking slightly.

There are now a couple of places where we need to know the actual
 stream position indicator, not just the offset of the data we've
 read out of the ogg_sync_state.
Make a function to compute this, document it, and use it.

--- a/src/opusfile.c

+++ b/src/opusfile.c

@@ -132,6 +132,8 @@

   return err;

 }

+/*The read/seek functions track absolute position within the stream.*/

+

 /*Read a little more data from the file/pipe into the ogg_sync framer.*/

 static int op_get_data(OggOpusFile *_of){

   char *buffer;

@@ -158,7 +160,13 @@

   return 0;

 }

-/*The read/seek functions track absolute position within the stream.*/

+/*Get the current position indicator of the underlying source.

+  This should be the same as the value reported by tell().*/

+static opus_int64 op_position(OggOpusFile *_of){

+  /*The current position indicator is _not_ simply offset.

+    We may also have unprocessed, buffered data in the sync state.*/

+  return _of->offset+_of->oy.fill-_of->oy.returned;

+}

 /*From the head of the stream, get the next page.

   _boundary specifies if the function is allowed to fetch more data from the

@@ -190,7 +198,7 @@

            including buffered sync data, then treat this as EOF.

           Otherwise treat it as a read error.*/

         if(_boundary<0)_boundary=_of->end;

-        read_offset=_of->offset+_of->oy.fill-_of->oy.returned;

+        read_offset=op_position(_of);

         return read_offset>=_boundary?OP_FALSE:ret;

       }

     }

@@ -1247,8 +1255,7 @@

   *&os_start=_of->os;

   start_offset=_of->offset;

   memcpy(op_start,_of->op,sizeof(*op_start)*start_op_count);

-  OP_ASSERT((*_of->callbacks.tell)(_of->source)==

-   start_offset+oy_start.fill-oy_start.returned);

+  OP_ASSERT((*_of->callbacks.tell)(_of->source)==op_position(_of));

   ogg_sync_init(&_of->oy);

   ogg_stream_init(&_of->os,-1);

   ret=op_open_seekable2_impl(_of);

@@ -1264,9 +1271,8 @@

   _of->prev_packet_gp=_of->links[0].pcm_start;

   _of->cur_discard_count=_of->links[0].head.pre_skip;

   if(OP_UNLIKELY(ret<0))return ret;

-  /*And seek back to the start of the first link.*/

-  ret=(*_of->callbacks.seek)(_of->source,

-   start_offset+oy_start.fill-oy_start.returned,SEEK_SET);

+  /*And restore the position indicator.*/

+  ret=(*_of->callbacks.seek)(_of->source,op_position(_of),SEEK_SET);

   return OP_UNLIKELY(ret<0)?OP_EREAD:0;

 }