From 61e438df2287d83dfe17e2497da0a41672e6df05 Mon Sep 17 00:00:00 2001
From: Torbjörn Andersson
Date: Tue, 19 Oct 2004 08:47:10 +0000
Subject: Made the calculation of _samples_per_tick a bit less prone to
 arithmetic overflow. It failed if the output rate was 44100 Hz. (It didn't
 use to, but somewhere along the line an unsigned value was changed to a
 signed. This seemed like a better fix, though.)

svn-id: r15610
---
 backends/midi/emumidi.h | 12 ++++++++++--
 1 file changed, 10 insertions(+), 2 deletions(-)

(limited to 'backends/midi')

diff --git a/backends/midi/emumidi.h b/backends/midi/emumidi.h
index 787d8912f7..529662b7ee 100644
--- a/backends/midi/emumidi.h
+++ b/backends/midi/emumidi.h
@@ -54,7 +54,14 @@ public:
 
 	int open() {
 		_isOpen = true;
-		_samples_per_tick = (getRate() << FIXP_SHIFT) / BASE_FREQ;
+
+		int d = getRate() / BASE_FREQ;
+		int r = getRate() % BASE_FREQ;
+
+		// This is equivalent to (getRate() << FIXP_SHIFT) / BASE_FREQ
+		// but less prone to arithmetic overflow.
+
+		_samples_per_tick = (d << FIXP_SHIFT) + (r << FIXP_SHIFT) / BASE_FREQ;
 		return 0;
 	}
 
@@ -71,11 +78,12 @@ public:
 		const int stereoFactor = isStereo() ? 2 : 1;
 		int len = numSamples / stereoFactor;
 		int step;
-	
+
 		do {
 			step = len;
 			if (step > (_next_tick >> FIXP_SHIFT))
 				step = (_next_tick >> FIXP_SHIFT);
+
 			generate_samples(data, step);
 	
 			_next_tick -= step << FIXP_SHIFT;
-- 
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