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Xext: Fix edge case with {Positive, Negative}Transition triggers. 

The {Positive,Negative}Transition triggers only fire when the counter
goes from strictly {below,above} the threshold.  If
SyncComputeBracketValues gets called exactly at this threshold we may update
the bracket values so that the counter is not updated past the threshold.

Signed-off-by: Christopher James Halse Rogers <christopher.halse.rogers@canonical.com>
Reviewed-by: Adam Jackson <ajax@redhat.com>
Signed-off-by: Keith Packard <keithp@keithp.com>
This commit is contained in:
Christopher James Halse Rogers 2010-12-06 11:24:00 +11:00 committed by Keith Packard
parent f1542f1d71
commit b55bf24858
1 changed files with 22 additions and 0 deletions
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22
Xext/sync.c
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@ -1059,6 +1059,17 @@ SyncComputeBracketValues(SyncCounter *pCounter)
{ {
psci->bracket_less = pTrigger->test_value; psci->bracket_less = pTrigger->test_value;
pnewltval = &psci->bracket_less; pnewltval = &psci->bracket_less;
} else if (XSyncValueEqual(pCounter->value, pTrigger->test_value) &&
XSyncValueLessThan(pTrigger->test_value,
psci->bracket_greater))
{
/*
* The value is exactly equal to our threshold. We want one
* more event in the positive direction to ensure we pick up
* when the value *exceeds* this threshold.
*/
psci->bracket_greater = pTrigger->test_value;
pnewgtval = &psci->bracket_greater;
} }
} }
else if (pTrigger->test_type == XSyncPositiveTransition && else if (pTrigger->test_type == XSyncPositiveTransition &&
@ -1069,6 +1080,17 @@ SyncComputeBracketValues(SyncCounter *pCounter)
{ {
psci->bracket_greater = pTrigger->test_value; psci->bracket_greater = pTrigger->test_value;
pnewgtval = &psci->bracket_greater; pnewgtval = &psci->bracket_greater;
} else if (XSyncValueEqual(pCounter->value, pTrigger->test_value) &&
XSyncValueGreaterThan(pTrigger->test_value,
psci->bracket_less))
{
/*
* The value is exactly equal to our threshold. We want one
* more event in the negative direction to ensure we pick up
* when the value is less than this threshold.
*/
psci->bracket_less = pTrigger->test_value;
pnewltval = &psci->bracket_less;
} }
} }
} /* end for each trigger */ } /* end for each trigger */