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/***********************************************************************
*
* Name: sys_sppt.c
*
* Purpose: Support Routines for Modules 3 and 4 of MPX-PC
*
* Sample Call:
* sys_init()
* sys_exit()
*
* Procedures In Module:
* sys_init - Sets up interrupt vector 60 for MPX-PC
* sys_exit - Resets interrupt vector 60 and exits to DOS
*
*
****************************************************************************/
#include <stdio.h>
#include <dos.h>
#include "mpx.h"
void interrupt (*vect60)(); /* Storage for DOS int 60h */
/* interrupt vector. */
void sys_init()
{
/* set up interrupt vector for MPX sys_calls */
vect60 = getvect(0x60);
setvect(0x60,&sys_call);
// set up the clock
clock_open();
// set up com
com_open(&com_eflag, 1200);
// set up printer
prt_open(&prt_eflag);
// set up con
con_open(&con_eflag);
}
void sys_exit()
{
disable();
// restore the clock
clock_close();
// close IO devices
com_close();
con_close();
prt_close();
/* restore interrupt vector 60 and exit */
setvect(0x60,vect60);
enable();
exit();
}
// dispatch the process at the head of the ready queue
void interrupt dispatch()
{
disable();
if (DEBUG_PRINTS) {printf("in dispatch \n ");}
cop = ready_queue_locked;
// kill zombie processes
while (cop->state == ZOMBIE) {
remove_pcb(&ready_queue_locked, cop);
freemem(cop->loadaddr);
free_pcb(pcb_list, cop);
cop = ready_queue_locked;
}
// skip over suspended processes
while (cop != NULL && cop->suspend == SUSPENDED) {
cop = cop -> next;
}
if (DEBUG_PRINTS){
if (cop == NULL) {
printf("!!cop null?!!!\n");
} else {
printf("cop - %s\n", cop->name);
}
}
remove_pcb(&ready_queue_locked, cop);
cop->state = RUNNING;
enable();
_SP = cop -> stack_ptr;
}
void interrupt sys_call()
{
static parm *parm_add;
if (DEBUG_PRINTS) {printf("in sys_call \n ");}
/* Save stack pointer for current process */
cop->stack_ptr = _SP;
/* Get address of sys_call parameters */
parm_add = _SP + 0x1c; // parameter offset = 0x1C
/* Note that you should save this parameter address
somewhere in the pcb as suggested below*/
cop->parm_add = parm_add;
_SP = &sys_stack[STACK_SIZE-1];
// find out if the process wants to die... and kill it
if (parm_add->op_number == EXIT_CODE) {
freemem(cop->loadaddr);
free_pcb(pcb_list, cop);
// NOTE: the process just made this sys_req so it cannot have any io
} else {
IO_sched(cop);
}
dispatch();
}
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