From d8fc8ca7bac8f378c4ff7bbc02f22a37ac72a792 Mon Sep 17 00:00:00 2001
From: Max Kellermann <max@duempel.org>
Date: Tue, 13 Jan 2009 21:25:19 +0100
Subject: playlist: implement Fisher-Yates shuffle properly
MPD's shuffling algorithm was not implemented well: it considers songs
which were already swapped, making it somewhat non-random.
Fix the Fisher-Yates shuffle algorithm by passing the proper bounds to
the PRNG.
---
src/playlist.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
(limited to 'src/playlist.c')
diff --git a/src/playlist.c b/src/playlist.c
index 8cffefc5e..e680af1e6 100644
--- a/src/playlist.c
+++ b/src/playlist.c
@@ -1118,7 +1118,7 @@ static void randomizeOrder(int start, int end)
clearPlayerQueue();
for (i = start; i <= end; i++) {
- ri = g_rand_int_range(g_rand, start, end + 1);
+ ri = g_rand_int_range(g_rand, i, end + 1);
if (ri == playlist.current)
playlist.current = i;
else if (i == playlist.current)
@@ -1201,7 +1201,7 @@ void shufflePlaylist(void)
}
/* shuffle the rest of the list */
for (; i < playlist.length; i++) {
- ri = g_rand_int_range(g_rand, 1, playlist.length);
+ ri = g_rand_int_range(g_rand, i, playlist.length);
swapSongs(i, ri);
}
--
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