Add option to prevent rewinding to the beginning of a track to prevent
loosing the current resume position.

Initially contributed by Dave Slusher
---
 apps/cuesheet.c            |   14 +++++++++++---
 apps/gui/wps.c             |    8 +++++++-
 apps/lang/english.lang     |   42 ++++++++++++++++++++++++++++++++++++++++++
 apps/menus/settings_menu.c |    4 +++-
 apps/metadata.c            |   10 ++++++++++
 apps/metadata.h            |    1 +
 apps/settings.h            |    5 +++++
 apps/settings_list.c       |    6 ++++++
 8 files changed, 85 insertions(+), 5 deletions(-)

diff --git a/apps/cuesheet.c b/apps/cuesheet.c
index a6831fa..aa16e64 100644
--- a/apps/cuesheet.c
+++ b/apps/cuesheet.c
@@ -319,7 +319,14 @@ bool display_cuesheet_content(char* filename)
 bool curr_cuesheet_skip(struct cuesheet *cue, int direction, unsigned long curr_pos)
 {
     int track = cue_find_current_track(cue, curr_pos);
-    
+    bool prevent_skipback = false;
+
+#if defined(HAVE_TAGCACHE) && CONFIG_CODEC == SWCODEC
+    /* Protect resume position by disallowing skipback to 00:00 of
+       current track? */
+    prevent_skipback = disallow_skipback(audio_current_track());
+#endif
+
     if (direction >= 0 && track == cue->track_count - 1)
     {
         /* we want to get out of the cuesheet */
@@ -334,8 +341,9 @@ bool curr_cuesheet_skip(struct cuesheet *cue, int direction, unsigned long curr_
             to previous cuesheet segment. If skipping backward after
             DEFAULT_SKIP_TRESH seconds have elapsed, skip to the start of the
             current cuesheet segment */
-            if (direction == 1 || 
-                  ((curr_pos - cue->tracks[track].offset) < DEFAULT_SKIP_TRESH))
+            if (direction == 1
+                || ((curr_pos - cue->tracks[track].offset) < DEFAULT_SKIP_TRESH)
+                || prevent_skipback)
             {
                 track += direction;
             }
diff --git a/apps/gui/wps.c b/apps/gui/wps.c
index 44e4adb..f83f8d2 100644
--- a/apps/gui/wps.c
+++ b/apps/gui/wps.c
@@ -458,7 +458,13 @@ static void change_dir(int direction)
 static void prev_track(unsigned long skip_thresh)
 {
     struct wps_state *state = skin_get_global_state();
-    if (state->id3->elapsed < skip_thresh)
+    bool prevent_skipback = false;
+
+#if defined(HAVE_TAGCACHE) && CONFIG_CODEC == SWCODEC
+    prevent_skipback = disallow_skipback(state->id3);
+#endif
+        
+    if (state->id3->elapsed < skip_thresh || prevent_skipback)
     {
         audio_prev();
         return;
diff --git a/apps/lang/english.lang b/apps/lang/english.lang
index 30fb003..d74e5b0 100644
--- a/apps/lang/english.lang
+++ b/apps/lang/english.lang
@@ -12744,3 +12744,45 @@
     *: "In custom directories only"
   </voice>
 </phrase>
+<phrase>
+  id: LANG_AUTORESUME_SKIPBACK
+  desc: Skipback settings menu to enable/disable resume
+  user: core
+  <source>
+    *: "Allow skip back to intro"
+  </source>
+  <dest>
+    *: "Allow skip back to intro"
+  </dest>
+  <voice>
+    *: "Allow skip back to intro"
+  </voice>
+</phrase>
+<phrase>
+  id: LANG_AUTORESUME_SKIPBACK_ALWAYS
+  desc: Skipback settings menu to enable/disable resume
+  user: core
+  <source>
+    *: "Always (may lose resume position)"
+  </source>
+  <dest>
+    *: "Always (may lose resume position)"
+  </dest>
+  <voice>
+    *: "Always. May lose resume position"
+  </voice>
+</phrase>
+<phrase>
+  id: LANG_AUTORESUME_SKIPBACK_NONRESUME
+  desc: Skipback settings menu to enable/disable resume
+  user: core
+  <source>
+    *: "Not when resumable on automatic track change"
+  </source>
+  <dest>
+    *: "Not when resumable on automatic track change"
+  </dest>
+  <voice>
+    *: "Not when resumable on automatic track change"
+  </voice>
+</phrase>
diff --git a/apps/menus/settings_menu.c b/apps/menus/settings_menu.c
index b3003bf..4c266b2 100644
--- a/apps/menus/settings_menu.c
+++ b/apps/menus/settings_menu.c
@@ -416,10 +416,12 @@ MENUITEM_SETTING(autoresume_enable, &global_settings.autoresume_enable,
                  autoresume_callback);
 MENUITEM_SETTING(autoresume_automatic, &global_settings.autoresume_automatic,
                  autoresume_nexttrack_callback);
+MENUITEM_SETTING(autoresume_skipback, &global_settings.autoresume_skipback,
+                 NULL);
 
 MAKE_MENU(autoresume_menu, ID2P(LANG_AUTORESUME),
           0, Icon_NOICON,
-          &autoresume_enable, &autoresume_automatic);
+          &autoresume_enable, &autoresume_automatic, &autoresume_skipback);
 
 #endif /* CONFIG_CODEC == SWCODEC */
 #endif /* HAVE_TAGCACHE */
diff --git a/apps/metadata.c b/apps/metadata.c
index 46b9482..22cb027 100644
--- a/apps/metadata.c
+++ b/apps/metadata.c
@@ -474,6 +474,16 @@ bool autoresumable(struct mp3entry *id3)
     return is_resumable;
 }
 
+bool disallow_skipback(struct mp3entry *id3)
+{
+    return global_settings.autoresume_enable
+        && global_settings.autoresume_skipback != AUTORESUME_SKIPBACK_ALWAYS
+        && (global_settings.autoresume_skipback == AUTORESUME_SKIPBACK_NEVER
+            || global_settings.autoresume_automatic == AUTORESUME_NEXTTRACK_ALWAYS
+            || (global_settings.autoresume_automatic == AUTORESUME_NEXTTRACK_CUSTOM
+                && autoresumable(id3)));
+}
+
 #endif  /* SWCODEC */
 #endif  /* HAVE_TAGCACHE */
 #endif  /* __PCTOOL__ */
diff --git a/apps/metadata.h b/apps/metadata.h
index 4c7e94f..d17478d 100644
--- a/apps/metadata.h
+++ b/apps/metadata.h
@@ -312,6 +312,7 @@ void strip_tags(int handle_id);
 
 #ifdef HAVE_TAGCACHE
 bool autoresumable(struct mp3entry *id3);
+bool disallow_skipback(struct mp3entry *id3);
 #endif
 
 #endif
diff --git a/apps/settings.h b/apps/settings.h
index 0734cf0..0723d30 100644
--- a/apps/settings.h
+++ b/apps/settings.h
@@ -129,6 +129,9 @@ enum { SCROLLBAR_OFF = 0, SCROLLBAR_LEFT, SCROLLBAR_RIGHT };
 enum { AUTORESUME_NEXTTRACK_NEVER = 0, AUTORESUME_NEXTTRACK_ALWAYS,
        AUTORESUME_NEXTTRACK_CUSTOM};
 
+enum { AUTORESUME_SKIPBACK_ALWAYS = 0, AUTORESUME_SKIPBACK_NONRESUME,
+       AUTORESUME_SKIPBACK_NEVER };
+
 /* Alarm settings */
 #ifdef HAVE_RTC_ALARM
 enum {  ALARM_START_WPS = 0,
@@ -584,6 +587,8 @@ struct user_settings
     int autoresume_automatic; /* resume next track? 0=never, 1=always,
                                  2=custom */
     unsigned char autoresume_paths[MAX_PATHNAME+1]; /* colon-separated list */
+    int autoresume_skipback;  /* skipback for resumable tracks? 0=do skip back,
+                                 1=only for nonresumable tracks, 2=always */
     bool runtimedb;           /* runtime database active? */
 #endif /* HAVE_TAGCACHE */
 
diff --git a/apps/settings_list.c b/apps/settings_list.c
index 2d73028..616b0c3 100644
--- a/apps/settings_list.c
+++ b/apps/settings_list.c
@@ -1270,6 +1270,12 @@ const struct settings_list settings[] = {
                    ID2P(LANG_AUTORESUME_CUSTOM)),
     TEXT_SETTING(0, autoresume_paths, "autoresume next track paths",
                  "/podcast:/podcasts", NULL, NULL),
+    CHOICE_SETTING(0, autoresume_skipback, LANG_AUTORESUME_SKIPBACK,
+                   AUTORESUME_SKIPBACK_NONRESUME,
+                   "autoresume skipback", "always,nonresumable,never", NULL, 3,
+                   ID2P(LANG_AUTORESUME_SKIPBACK_ALWAYS),
+                   ID2P(LANG_AUTORESUME_SKIPBACK_NONRESUME),
+                   ID2P(LANG_SET_BOOL_NO)),
 #endif                  
 
     OFFON_SETTING(0, runtimedb, LANG_RUNTIMEDB_ACTIVE, false,
-- 
1.7.1