Function projectm_playlist_play_previous 

pub unsafe extern "C" fn projectm_playlist_play_previous(
    instance: projectm_playlist_handle,
    hard_cut: bool,
) -> u32

@brief Plays the previous playlist item and returns the index of the new preset.

If shuffle is on, it will select a random preset, otherwise the next in the playlist. If the end of the playlist is reached in continuous mode, it will wrap back to 0.

The old playlist item is added to the history.

@param instance The playlist manager instance. @param hard_cut If true, the preset transition is instant. If true, a smooth transition is played. @return The new playlist position. If the playlist is empty, 0 will be returned.