buggy-sched.c

用于汇编领域的,运用于OS的MAIN函数.基于硬件基础的源代码

#include "hos.h"
struct task_struct * next_p(){
	// select next processor
	return (current->next_run);
}

#define switch_to(prev, next, last) do { \
	asm volatile("movl %%esp, %0\n\t" /*save esp*/ \
			"movl %4, %%esp\n\t" /*restore esp*/ \
			"movl $1f, %1\n\t" /*save eip*/ \
			"pushl %5\n\t" /*restore eip*/ \
			"movl %6, %%eax \n\t" \
			"movl %%eax, %3\n" \
			"1:\t" \
			"movl %%ebx, %2\n\t" \
			"cli\n\t" \
			:"=m"(prev->esp), "=m"(prev->eip), \
			 "=b"(last), "=m"(init_tss.esp0) \
			:"m"(next->esp), "m"(next->eip), \
			 "m"(next->esp0)); \
}while (0)
void schedule(void){
	unsigned long addr; float x=0.0; int i;
	if (!current->need_reschedule) return;
	//get next process and start it
	struct task_struct *prev, *next;
	prev=current;
	current->need_reschedule=0; // reset
	next=next_p();
	current=next;
	if (next!=prev){
		printk("about to switch. current is %x\n",current);
		for(i=0;i<100000000;i++)
			x=x+1.0;
		switch_to(prev,next,prev);
		asm("ret\n\t"::);
		/*
		asm("popl %%eax\n\t"
		    "movl %%eax, %0\n\t"
		    :"=m"(addr):);
		printk("p1_body is %x, return addr: %x\n", p1_body, addr);
		for(;;);
		*/
	}
}