Use crc32 of filename to resume tracks

As well as using an index, which breaks when a file is added or
removed, use the crc32 of the filename. When the crc32 check passes the
index is used directly. When it fails, the slow path is taken checking
each file name in the playlist until the right crc is found. If that fails
the playlist is started from the beginning.

See http://www.rockbox.org/tracker/6411

Bump plugin API and nvram version numbers

Change-Id: I156f61a9f1ac428b4a682bc680379cb6b60b1b10
Reviewed-on: http://gerrit.rockbox.org/372
Tested-by: Jonathan Gordon <rockbox@jdgordon.info>
Reviewed-by: Jonathan Gordon <rockbox@jdgordon.info>

1 files changed, 41 insertions, 0 deletions

diff --git a/apps/playlist.c b/apps/playlist.c
index c5e2e83462..35b7e35baa 100755
--- a/apps/playlist.c
+++ b/apps/playlist.c
@@ -2514,6 +2514,44 @@ int playlist_shuffle(int random_seed, int start_index)
     return playlist->index;
 }
 
+/* returns the crc32 of the filename of the track at the specified index */
+unsigned int playlist_get_filename_crc32(struct playlist_info *playlist,
+                                         int index)
+{
+    struct playlist_track_info track_info;
+    if (playlist_get_track_info(playlist, index, &track_info) == -1)
+        return -1;
+
+    return crc_32(track_info.filename, strlen(track_info.filename), -1);
+}
+
+/* resume a playlist track with the given crc_32 of the track name. */
+void playlist_resume_track(int start_index, unsigned int crc, int offset)
+{
+    int i;
+    unsigned int tmp_crc;
+    struct playlist_info* playlist = &current_playlist;
+    tmp_crc = playlist_get_filename_crc32(playlist, start_index);
+    if (tmp_crc == crc)
+    {
+        playlist_start(start_index, offset);
+        return;
+    }
+
+    for (i = 0 ; i < playlist->amount; i++)
+    {
+        tmp_crc = playlist_get_filename_crc32(playlist, i);
+        if (tmp_crc == crc)
+        {
+            playlist_start(i, offset);
+            return;
+        }
+    }
+
+    /* If we got here the file wasnt found, so start from the beginning */
+    playlist_start(0,0);
+}
+
 /* start playing current playlist at specified index/offset */
 void playlist_start(int start_index, int offset)
 {
@@ -2726,7 +2764,9 @@ int playlist_update_resume_info(const struct mp3entry* id3)
         if (global_status.resume_index  != playlist->index ||
             global_status.resume_offset != id3->offset)
         {
+            unsigned int crc = crc_32(id3->path, strlen(id3->path), -1);
             global_status.resume_index  = playlist->index;
+            global_status.resume_crc32 = crc;
             global_status.resume_offset = id3->offset;
             status_save();
         }
@@ -2734,6 +2774,7 @@ int playlist_update_resume_info(const struct mp3entry* id3)
     else
     {
         global_status.resume_index  = -1;
+        global_status.resume_crc32 = -1;
         global_status.resume_offset = -1;
         status_save();
     }