Changeset 34695 in vbox for trunk/src

Timestamp:

Dec 3, 2010 1:38:26 PM (14 years ago)

Author:

vboxsync

Message:

PIC: Reversed IRQ flip-flop polarity.

File:

• trunk/src/VBox/Devices/PC/DevPIC.cpp (modified) (1 diff)

trunk/src/VBox/Devices/PC/DevPIC.cpp

@@ -359 +359 @@
     DumpPICState(&pThis->aPics[1], "picSetIrq");
     STAM_COUNTER_INC(&pThis->CTXSUFF(StatSetIrq));
+    if ((iLevel & PDM_IRQ_LEVEL_FLIP_FLOP) == PDM_IRQ_LEVEL_FLIP_FLOP)
+    {
+        /* A flip-flop lowers the IRQ line and immediately raises it, so
+         * that a rising edge is guaranteed to occur. Note that the IRQ
+         * line must be held high for a while to avoid spurious interrupts.
+         */
+        pic_set_irq1(&pThis->aPics[iIrq >> 3], iIrq & 7, 0);
+        pic_update_irq(pThis);
+    }
     pic_set_irq1(&pThis->aPics[iIrq >> 3], iIrq & 7, iLevel & PDM_IRQ_LEVEL_HIGH);
     pic_update_irq(pThis);
-    if ((iLevel & PDM_IRQ_LEVEL_FLIP_FLOP) == PDM_IRQ_LEVEL_FLIP_FLOP)
-    {
-        pic_set_irq1(&pThis->aPics[iIrq >> 3], iIrq & 7, 0);
-        pic_update_irq(pThis);
-    }
 }