xinu: Desktop/xinu_mips-1.0.2.tar/xinu_mips-1.0.2/system/clockintr.c Source File

00001 
00007 /* Embedded XINU, Copyright (C) 2007.  All rights reserved. */
00008 
00009 #include <kernel.h>
00010 #include <clock.h>
00011 
00012 extern void wakeup(void);
00013 extern syscall resched(void);
00014 extern void restore_intr(void *);
00015 
00020 interrupt clockintr(void)
00021 {
00022         clock_update(time_intr_freq);
00023 
00024         /* Another millisecond has passed. */
00025         ctr_mS--;
00026 
00027         /* Update global second counter. */
00028         if (0 == ctr_mS) 
00029         {
00030                 clocktime++;
00031                 ctr_mS = 1000;
00032         }
00033 
00034         /* If sleepq is not empty, decrement first key.   */
00035         /* If key reaches zero, call wakeup.              */
00036         if (nonempty(sleepq))
00037         {
00038                 if (--firstkey(sleepq) <= 0)
00039                 restore_intr(&wakeup);
00040         }
00041 
00042         /* Check to see if this proc should be preempted. */
00043         if (--preempt <= 0)
00044         {  
00045                 restore_intr(&resched);
00046         }
00047 }