80X86 MULTI-TASKING OPERATION SYSTEM: timer.c Source File

00001 /*******************
00002 *Project: 80X86 32BIT MULTI TASKING OPERATING SYSTEM
00003 *Description:driver for 8254 programable interval timer (PIT)
00004 *
00005 *File:timer.c
00006 *Author: Book Chen
00007 *Date: 2010.01.01
00008 ********************
00009 */
00010 #include "includes.h"
00011 
00012 TIMER_CONTROL TimerCtrl;
00013  
00014 void TimerInit(void){
00015     PicIrqDisable(IRQ0_TIMER);
00016     TimerCtrl.Timer=0;
00017     OutByte(TIMER_MODE,RATE_GENERATOR);
00018     OutByte(TIMER0,(U8)(TIMER_FREQ/HZ));
00019     OutByte(TIMER0,(U8)((TIMER_FREQ/HZ)>>8));
00020     InterruptIrqHandlerSet(IRQ0_TIMER,TimerHandler);
00021     PicIrqEnable(IRQ0_TIMER);
00022 }
00023 
00024 void TimerHandler(void){
00025     if(TimerCtrl.Timer!=0) TimerCtrl.Timer--;
00026     if(KeyboardCtrl.Timer!=0) KeyboardCtrl.Timer--;
00027     if(ShellCtrl.Timer!=0) ShellCtrl.Timer--;
00028     if(XmodemCtrl.Timer!=0) XmodemCtrl.Timer--;
00029     if(Fdc1Ctrl.Timer!=0) Fdc1Ctrl.Timer--;
00030     if(TaskbCtrl.Timer!=0) TaskbCtrl.Timer--;
00031     if(TaskcCtrl.Timer!=0) TaskcCtrl.Timer--;
00032     if(OsSchedulerCtrl.TaskSwitchTimer!=0) OsSchedulerCtrl.TaskSwitchTimer--;
00033     if(OsRunning==true){
00034         #if(OS_TIME_EVENT_ENABLE==1)
00035             OsTimeEventHandler(); 
00036         #endif
00037         if(OsSchedulerCtrl.TaskSwitchTimer==0){
00038             #if(OS_INT_LEVEL_CSW_ENABLE==1)
00039                 OsSchedulerNextTaskFind();
00040             #endif
00041         }
00042     }
00043 }