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Rockbox mail archiveSubject: RE: Rockbox for the playerRE: Rockbox for the player
From: Lee Marlow <lmarlow_at_yahoo.com>
Date: Thu, 12 Sep 2002 09:40:07 -0700 (PDT) Since we know the seed used to shuffle, can we somehow backtrack through the shuffle process and find out what the original index was without storing all of the original indices? Basically have a function like this: int playlist_original_index(int seed, int shuffled_index); I think we would need to find the inverse of the seed used. I don't remember much from my number theory class and don't know much about the Mersenne twister we use, so I can't "show you the code" just yet. (Sorry, Linus :) -Lee --- Daniel Stenberg <daniel_at_haxx.se> wrote: > On Thu, 12 Sep 2002, Ed Wilson wrote: > > > 1) When showing the playlist number 4/1567 etc.. > the 4 is the current count > > of how many tracks have been played, but on the > old firmware it referred to > > the position of the song within the playlist which > was much easier to > > remember so that the song could be removed from > the playlist at a later > > date. > > The superb (if I may say so) efficiency of playlist > in Rockbox of course come > with a price. > > We only keep a single list in memory, and that list > is shuffled when you > select shuffle. When advancing down this list, we > have no knowledge at all > about what "original" position a particular index > has. > > To be able to know that, we'd have to store an > additional 16 bit number for > each playlist entry. Quite doable, but not done > today. > > -- > Daniel "Bagder" Stenberg -- http://rockbox.haxx.se/ > __________________________________________________ Do you Yahoo!? Yahoo! News - Today's headlines http://news.yahoo.com Received on 2002-09-12 Page template was last modified "Tue Sep 7 00:00:02 2021" The Rockbox Crew -- Privacy Policy |