VBox

Timestamp:

Dec 9, 2010 3:05:54 PM (14 years ago)

Author:

vboxsync

Message:

PIT: Avoid double calls of timer handler caused by integer truncation.

File:

trunk/src/VBox/Devices/PC/DevPit-i8254.cpp

-              r34692
+              r34896
     uint32_t period2;
+    d = ASMMultU64ByU32DivByU32(current_time - s->count_load_time, PIT_FREQ, TMTimerGetFreq(pTimer));
+    /* Add one to current_time; if we don't, integer truncation will cause
+     * the algorithm to think that at the end of each period, it's still
+     * within the first one instead of at the beginning of the next one.
+     */
+    d = ASMMultU64ByU32DivByU32(current_time + 1 - s->count_load_time, PIT_FREQ, TMTimerGetFreq(pTimer));
     switch(s->mode) {
     default:

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