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ALSA: fix incorrect rounding direction in snd_interval_ratnum()

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The direction of rounding is incorrect in the snd_interval_ratnum()
It was detected with following parameters (sb8 driver playing
8kHz stereo file):
 - num is always 1000000
 - requested frequency rate is from 7999 to 7999 (single frequency)

The first loop calculates div_down(num, freq->min) which is 125.
Thus, a frequency range's minimum value is 1000000 / 125 = 8000 Hz.
The second loop calculates div_up(num, freq->max) which is 126
The frequency range's maximum value is 1000000 / 126 = 7936 Hz.
The range maximum is lower than the range minimum so the function
fails due to empty result range.

Signed-off-by: Krzysztof Helt <krzysztof.h1@wp.pl>
Signed-off-by: Takashi Iwai <tiwai@suse.de>
This commit is contained in:
Krzysztof Helt 2009-12-19 18:31:04 +01:00 committed by Takashi Iwai
parent ef86f581f7
commit 40962d7c74
1 changed files with 2 additions and 2 deletions
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4
sound/core/pcm_lib.c
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@ -758,7 +758,7 @@ int snd_interval_ratnum(struct snd_interval *i,
int diff;
if (q == 0)
q = 1;
den = div_down(num, q);
den = div_up(num, q);
if (den < rats[k].den_min)
continue;
if (den > rats[k].den_max)
@ -794,7 +794,7 @@ int snd_interval_ratnum(struct snd_interval *i,
i->empty = 1;
return -EINVAL;
}
den = div_up(num, q);
den = div_down(num, q);
if (den > rats[k].den_max)
continue;
if (den < rats[k].den_min)