From 909e181a497074c52e0be927c007cb6b6d66fc8c
From: Michael Forney <mforney@mforney.org>
Date: Mon, 15 Feb 2021 09:40:11 +0000
Subject: games/snes: use linear interpolation to resample


This is still not ideal, but noticably better than nearest-neighbor.

diff b78eaf915465b6d6d13f2dc36964c9aad9a2b76c 909e181a497074c52e0be927c007cb6b6d66fc8c
--- a/sys/src/games/snes/dsp.c	Mon Feb 15 01:38:22 2021
+++ b/sys/src/games/snes/dsp.c	Mon Feb 15 01:40:11 2021
@@ -64,13 +64,17 @@
 static void
 audiosample(s16int *s)
 {
+	static s16int s1[2];
+
 	stime -= 1<<16;
 	do {
-		sbufp[0] = s[0];
-		sbufp[1] = s[1];
+		sbufp[0] = s[0] + ((s[0] - s1[0]) * stime >> 16);
+		sbufp[1] = s[1] + ((s[1] - s1[1]) * stime >> 16);
 		sbufp += 2;
 		stime += (32000<<16)/Freq;
 	} while(stime < 0);
+	s1[0] = s[0];
+	s1[1] = s[1];
 }
 
 int