sys.c

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/*
 *	ApOS (Another Project software for s3c2410)
 *	
 *	This program is free software; you can redistribute it and/or modify
 *	it under the terms of the GNU General Public License version 2 as
 *	published by the Free Software Foundation.
 *			
 *						Copyright caiyuqing
 *
 */
#include "../include/s3c2410/cpu.h"
#include "../include/kernel/sys.h"
#include "../include/kernel/sched.h"
#include "../include/kernel/signal.h"
#include "../include/kernel/task.h"
#include "../include/kernel/gui.h"

extern struct lcd_control_obj lcd_control_obj;
extern struct task_struct* current;
struct task_struct* task[NR_TASKS];
/*
 *	系统调用函数表
 */
fn_ptr sys_call_table[] = { 
	sys_enter_super,sys_fork,sys_singal,sys_sigaction,sys_free_process
	};
/*
 *	software interrupt处理函数
 *	所有的系统呼叫处理函数的形式参数都皆是 struct cpu_registers *regs
 *	
 *	其中：
 *		regs->r0 为系统呼叫号
 *		regs->r1 为系统呼叫参数1
 *		regs->r2 为系统呼叫参数2
 *		regs->r3 为系统呼叫参数3
 *
 *
 */
void do_system_call(struct cpu_registers *regs)
{
	unsigned int res;
	unsigned int signum;
	
	//从r0得到系统呼叫号
	fn_ptr fun;
	fun=sys_call_table[regs->r0];

	regs->r0=(*fun)(regs);
}

//0号系统调用使系统进入system模式
int sys_enter_super(struct cpu_registers *regs)
{
	unsigned int reg=read_spsr();
	reg|=SystemMode;
	write_spsr(reg);
}

/*
 *	1号系统调用
 */
int sys_fork(struct cpu_registers *regs)
{
	int nr=find_empty_process();
	if(nr==-1)
		return -1;
	else
	{
		copy_process(nr,regs);
	}
	return nr;
}

/*
 *	2号系统调用
 *	不可靠的信号设置函数
 */
int sys_singal(struct cpu_registers *regs)
{
	int 	signum=regs->r1;
	unsigned int handler=regs->r2;
	unsigned int restorer=regs->r3;
	
	struct sigaction tmp;

	/*
	 *	若信号不在定义的范围之内或信号是SIGKILL
	 *	则以失败返回
	 */
	if(signum<1||signum>32||signum==SIGKILL)
	{
		return -1;
	}

	tmp.sa_handler=(void (*)(int))handler;//sa_handler设置为用户指定的句柄
	tmp.sa_mask=0;//不对该信号进行屏蔽(信号触发时该信号处理函数将被调用)

	/*
	 *	SA_NOMASK置位，不阻止在指定的信号处理函数中再收到该信号
	 *	SA_ONESHOT置位，当指定的信号句柄被调用后则马上恢复成默认句柄
	 *
	 */
	tmp.sa_flags=SA_ONESHOT|SA_NOMASK;

	/*
	 *	restorer为信号句柄处理完毕后调用函数，该函数作用
	 *	是将用户堆栈恢复成调用信号句柄之前的状态
	 */
	tmp.sa_restorer=(void (*)(void))restorer;

	handler=(unsigned int)current->sigaction[signum].sa_handler;
	current->sigaction[signum]=tmp;

	return handler;//返回原信号句柄
}

/*
 *	可靠的信号设置函数
 */
int sys_sigaction(struct cpu_registers *regs)
{
	int 	signum=regs->r1;
	struct sigaction *action=regs->r2;
	struct sigaction *oldaction=regs->r3;
	struct sigaction tmp;
	
	if(signum<1||signum>32||signum==SIGKILL)
	{
		return -1;
	}
	
	tmp=current->sigaction[signum];
	
	current->sigaction[signum]=*action;
	*oldaction=tmp;
		
	if(current->sigaction[signum].sa_flags&SA_NOMASK)
	{
		current->sigaction[signum].sa_mask=0;
	}
	else
	{
		//对该信号进行屏蔽(信号触发时该信号处理函数不被调用)
		current->sigaction[signum].sa_mask|=(1<<signum);
	}
	
	return 0;
}
/*
 *	3号系统调用
 *	用于撤消进程
 */
int sys_free_process(struct cpu_registers *regs)
{
	return free_task(regs->r1);

}