From 962f2407d2a3579b7125f937d93d04ccbeb9a453 Mon Sep 17 00:00:00 2001
From: Max Kellermann <max@duempel.org>
Date: Sat, 3 Jan 2009 14:51:47 +0100
Subject: pcm_utils: use the custom PRNG for volume dithering

Don't use libc's rand() function, because it is slow.  Our own trivial
linear congruential generator is good enough for dithering.
---
 src/pcm_utils.c | 8 +++++++-
 1 file changed, 7 insertions(+), 1 deletion(-)

(limited to 'src/pcm_utils.c')

diff --git a/src/pcm_utils.c b/src/pcm_utils.c
index 46c5f2884..a7e7a3990 100644
--- a/src/pcm_utils.c
+++ b/src/pcm_utils.c
@@ -18,6 +18,7 @@
 
 #include "pcm_utils.h"
 #include "pcm_channels.h"
+#include "pcm_prng.h"
 #include "utils.h"
 #include "conf.h"
 #include "audio_format.h"
@@ -33,7 +34,12 @@
 static inline int
 pcm_dither(void)
 {
-	return (rand() & 511) - (rand() & 511);
+	static unsigned long state;
+	uint32_t r;
+
+	r = state = prng(state);
+
+	return (r & 511) - ((r >> 9) & 511);
 }
 
 /**
-- 
cgit v1.2.3