proc.c

这是《自己动手写操作系统》的原文件和代码

/*++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
                               proc.c
++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
                                                    Forrest Yu, 2005
++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++*/

#include "type.h"
#include "const.h"
#include "protect.h"
#include "string.h"
#include "proc.h"
#include "tty.h"
#include "console.h"
#include "global.h"
#include "proto.h"


/*======================================================================*
                              schedule
 *======================================================================*/
PUBLIC void schedule()
{
	PROCESS*	p;
	int		greatest_ticks = 0;

	while (!greatest_ticks) {
		for (p=proc_table; p<proc_table+NR_TASKS; p++) {
			if (p->ticks > greatest_ticks) {
				greatest_ticks = p->ticks;
				p_proc_ready = p;
			}
		}

		if (!greatest_ticks) {
			for (p=proc_table; p<proc_table+NR_TASKS; p++) {
				p->ticks = p->priority;
			}
		}
	}
}


/*======================================================================*
                           sys_get_ticks
 *======================================================================*/
PUBLIC int sys_get_ticks()
{
	return ticks;
}