+ unsigned int count1, count2, status;
+ long offset;
+
+ ioc_writeb (0, IOC_T0LATCH);
+ barrier ();
+ count1 = ioc_readb(IOC_T0CNTL) | (ioc_readb(IOC_T0CNTH) << 8);
+ barrier ();
+ status = ioc_readb(IOC_IRQREQA);
+ barrier ();
+ ioc_writeb (0, IOC_T0LATCH);
+ barrier ();
+ count2 = ioc_readb(IOC_T0CNTL) | (ioc_readb(IOC_T0CNTH) << 8);
+
+ offset = count2;
+ if (count2 < count1) {
+ /*
+ * We have not had an interrupt between reading count1
+ * and count2.
+ */
+ if (status & (1 << 5))
+ offset -= LATCH;
+ } else if (count2 > count1) {
+ /*
+ * We have just had another interrupt between reading
+ * count1 and count2.
+ */
+ offset -= LATCH;
+ }
+
+ offset = (LATCH - offset) * (tick_nsec / 1000);
+ return (offset + LATCH/2) / LATCH;