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Made the calculation of _samples_per_tick a bit less prone to arithmetic

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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
This commit is contained in:
Torbjörn Andersson 2004-10-19 08:47:10 +00:00
parent 4d3913d1b2
commit 61e438df22
1 changed files with 10 additions and 2 deletions
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12
backends/midi/emumidi.h
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@ -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;