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author | Torbjörn Andersson | 2004-10-19 08:47:10 +0000 |
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committer | Torbjörn Andersson | 2004-10-19 08:47:10 +0000 |
commit | 61e438df2287d83dfe17e2497da0a41672e6df05 (patch) | |
tree | 4d8ea47afb53c9c05a6450fa437602b02f9d413f /backends | |
parent | 4d3913d1b21d00692b0f761a8ade9d8b506cd7e0 (diff) | |
download | scummvm-rg350-61e438df2287d83dfe17e2497da0a41672e6df05.tar.gz scummvm-rg350-61e438df2287d83dfe17e2497da0a41672e6df05.tar.bz2 scummvm-rg350-61e438df2287d83dfe17e2497da0a41672e6df05.zip |
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
Diffstat (limited to 'backends')
-rw-r--r-- | backends/midi/emumidi.h | 12 |
1 files changed, 10 insertions, 2 deletions
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; |