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Subject[PATCH]: 2.4.0-testx: ac97_codec
In the current ac97_codec, computation of attenuation values may overflow
the register width, thus resulting in maximum volume when minimum was requested.
This patch adds overflow checks and limitations.

Tom

--- ac97_codec.c.orig Thu Nov 23 13:13:13 2000
+++ ac97_codec.c Thu Nov 23 13:20:01 2000
@@ -284,6 +284,10 @@
if (oss_channel == SOUND_MIXER_IGAIN) {
right = (right * mh->scale) / 100;
left = (left * mh->scale) / 100;
+ if (right >= mh->scale)
+ right = mh->scale-1;
+ if (left >= mh->scale)
+ left = mh->scale-1;
} else {
/* these may have 5 or 6 bit resolution */
if (oss_channel == SOUND_MIXER_VOLUME ||
@@ -294,27 +298,49 @@

right = ((100 - right) * scale) / 100;
left = ((100 - left) * scale) / 100;
- }
+ if (right >= scale)
+ right = scale-1;
+ if (left >= scale)
+ left = scale-1;
+ }
val = (left << 8) | right;
}
} else if (oss_channel == SOUND_MIXER_BASS) {
val = codec->codec_read(codec , mh->offset) & ~0x0f00;
- val |= ((((100 - left) * mh->scale) / 100) << 8) & 0x0e00;
+ left = ((100 - left) * mh->scale) / 100;
+ if (left >= mh->scale)
+ left = mh->scale-1;
+ val |= (left << 8) & 0x0e00;
} else if (oss_channel == SOUND_MIXER_TREBLE) {
val = codec->codec_read(codec , mh->offset) & ~0x000f;
- val |= (((100 - left) * mh->scale) / 100) & 0x000e;
+ left = ((100 - left) * mh->scale) / 100;
+ if (left >= mh->scale)
+ left = mh->scale-1;
+ val |= left & 0x000e;
} else if(left == 0) {
val = AC97_MUTE;
} else if (oss_channel == SOUND_MIXER_SPEAKER) {
- val = (((100 - left) * mh->scale) / 100) << 1;
+ left = ((100 - left) * mh->scale) / 100;
+ if (left >= mh->scale)
+ left = mh->scale-1;
+ val = left << 1;
} else if (oss_channel == SOUND_MIXER_PHONEIN) {
- val = (((100 - left) * mh->scale) / 100);
+ left = ((100 - left) * mh->scale) / 100;
+ if (left >= mh->scale)
+ left = mh->scale-1;
+ val = left;
} else if (oss_channel == SOUND_MIXER_PHONEOUT) {
scale = (1 << codec->bit_resolution);
- val = (((100 - left) * scale) / 100);
+ left = ((100 - left) * scale) / 100;
+ if (left >= mh->scale)
+ left = mh->scale-1;
+ val = left;
} else if (oss_channel == SOUND_MIXER_MIC) {
val = codec->codec_read(codec , mh->offset) & ~0x801f;
- val |= (((100 - left) * mh->scale) / 100);
+ left = ((100 - left) * mh->scale) / 100;
+ if (left >= mh->scale)
+ left = mh->scale-1;
+ val |= left;
/* the low bit is optional in the tone sliders and masking
it lets us avoid the 0xf 'bypass'.. */
}
-
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