diff --git a/sys.c b/sys.c
new file mode 100644
index 0000000..8f2d99f
--- /dev/null
+++ b/sys.c
@@ -0,0 +1,572 @@
+/*
+ *  linux/kernel/sys.c
+ *
+ *  (C) 1991  Linus Torvalds
+ */
+
+#include <errno.h>
+
+#include <linux/sched.h>	//调度程序头文件。定义了任务结构task_struct,任务0的数据,
+							//还有一些有关描述符参数设置和获取的嵌入式汇编函数宏语言
+#include <linux/tty.h>
+#include <linux/kernel.h>	//内核头文件
+#include <asm/segment.h>
+#include <sys/times.h>
+#include <sys/utsname.h>	//系统名称结构头文件
+
+#include <asm/io.h>
+#include <fcntl.h>
+int sys_ftime()
+{
+	return -ENOSYS;
+}
+
+int sys_break()
+{
+	return -ENOSYS;
+}
+
+int sys_ptrace()
+{
+	return -ENOSYS;
+}
+
+int sys_stty()
+{
+	return -ENOSYS;
+}
+
+int sys_gtty()
+{
+	return -ENOSYS;
+}
+
+int sys_rename()
+{
+	return -ENOSYS;
+}
+
+int sys_prof()
+{
+	return -ENOSYS;
+}
+
+int sys_setregid(int rgid, int egid)
+{
+	if (rgid>0) {
+		if ((current->gid == rgid) || 
+		    suser())
+			current->gid = rgid;
+		else
+			return(-EPERM);
+	}
+	if (egid>0) {
+		if ((current->gid == egid) ||
+		    (current->egid == egid) ||
+		    suser()) {
+			current->egid = egid;
+			current->sgid = egid;
+		} else
+			return(-EPERM);
+	}
+	return 0;
+}
+//设置进程组号
+int sys_setgid(int gid)
+{
+/*	return(sys_setregid(gid, gid)); */
+	if (suser())
+		current->gid = current->egid = current->sgid = gid;
+	else if ((gid == current->gid) || (gid == current->sgid))
+		current->egid = gid;
+	else
+		return -EPERM;
+	return 0;
+}
+
+int sys_acct()
+{
+	return -ENOSYS;
+}
+
+int sys_phys()
+{
+	return -ENOSYS;
+}
+
+int sys_lock()
+{
+	return -ENOSYS;
+}
+
+int sys_mpx()
+{
+	return -ENOSYS;
+}
+
+int sys_ulimit()
+{
+	return -ENOSYS;
+}
+//返回从1970年1月1号 开始记时的时间值(s)
+int sys_time(long * tloc)
+{
+	int i;
+
+	i = CURRENT_TIME;
+	if (tloc) {
+		verify_area(tloc,4);
+		put_fs_long(i,(unsigned long *)tloc);	//把时间值存储到用户空间
+		//段寄存器fs被默认地指向用户数据空间，因此此函数可利用fs段寄存器来访问用户空间中的值
+	}
+	return i;
+}
+
+/*
+ * Unprivileged users may change the real user id to the effective uid
+ * or vice versa.
+ */
+int sys_setreuid(int ruid, int euid)
+{
+	int old_ruid = current->uid;
+	
+	if (ruid>0) {
+		if ((current->euid==ruid) ||
+                    (old_ruid == ruid) ||
+		    suser())
+			current->uid = ruid;
+		else
+			return(-EPERM);
+	}
+	if (euid>0) {
+		if ((old_ruid == euid) ||
+                    (current->euid == euid) ||
+		    suser()) {
+			current->euid = euid;
+			current->suid = euid;
+		} else {
+			current->uid = old_ruid;
+			return(-EPERM);
+		}
+	}
+	return 0;
+}
+
+int sys_setuid(int uid)
+{
+/*	return(sys_setreuid(uid, uid)); */
+	if (suser())
+		current->uid = current->euid = current->suid = uid;
+	else if ((uid == current->uid) || (uid == current->suid))
+		current->euid = uid;
+	else
+		return -EPERM;
+	return(0);
+}
+
+int sys_stime(long * tptr)
+{
+	if (!suser())
+		return -EPERM;
+	startup_time = get_fs_long((unsigned long *)tptr) - jiffies/HZ;
+	return 0;
+}
+//获取当前任务运行时间统计值
+int sys_times(struct tms * tbuf)
+{
+	if (tbuf) {
+		verify_area(tbuf,sizeof *tbuf);
+		put_fs_long(current->utime,(unsigned long *)&tbuf->tms_utime);
+		put_fs_long(current->stime,(unsigned long *)&tbuf->tms_stime);
+		put_fs_long(current->cutime,(unsigned long *)&tbuf->tms_cutime);
+		put_fs_long(current->cstime,(unsigned long *)&tbuf->tms_cstime);
+	}
+	return jiffies;
+}
+//设置程序在内存中的末端位置
+int sys_brk(unsigned long end_data_seg)
+{
+	//如果参数值大于代码结尾，并且小于（堆栈-16kb），则设置新数据段结尾值
+	if (end_data_seg >= current->end_code &&
+	    end_data_seg < current->start_stack - 16384)
+		current->brk = end_data_seg;
+	return current->brk;
+}
+
+/*
+ * This needs some heave checking ...
+ * I just haven't get the stomach for it. I also don't fully
+ * understand sessions/pgrp etc. Let somebody who does explain it.
+ */
+int sys_setpgid(int pid, int pgid)
+{
+	int i;
+
+	if (!pid)
+		pid = current->pid;
+	if (!pgid)
+		pgid = current->pid;
+	for (i=0 ; i<NR_TASKS ; i++)
+		if (task[i] && task[i]->pid==pid) {
+			if (task[i]->leader)
+				return -EPERM;
+			if (task[i]->session != current->session)
+				return -EPERM;
+			task[i]->pgrp = pgid;
+			return 0;
+		}
+	return -ESRCH;
+}
+
+int sys_getpgrp(void)
+{
+	return current->pgrp;
+}
+
+int sys_setsid(void)
+{
+	if (current->leader && !suser())
+		return -EPERM;
+	current->leader = 1;
+	current->session = current->pgrp = current->pid;
+	current->tty = -1;
+	return current->pgrp;
+}
+
+int sys_getgroups()
+{
+	return -ENOSYS;
+}
+
+int sys_setgroups()
+{
+	return -ENOSYS;
+}
+
+int sys_uname(struct utsname * name)
+{
+	static struct utsname thisname = {
+		"linux .0","nodename","release ","version ","machine "
+	};
+	int i;
+
+	if (!name) return -ERROR;
+	verify_area(name,sizeof *name);
+	for(i=0;i<sizeof *name;i++)
+		put_fs_byte(((char *) &thisname)[i],i+(char *) name);	//用来访问用户程序的数据
+	return 0;
+}
+
+int sys_sethostname()
+{
+	return -ENOSYS;
+}
+
+int sys_getrlimit()
+{
+	return -ENOSYS;
+}
+
+int sys_setrlimit()
+{
+	return -ENOSYS;
+}
+
+int sys_getrusage()
+{
+	return -ENOSYS;
+}
+
+int sys_gettimeofday()
+{
+	return -ENOSYS;
+}
+
+int sys_settimeofday()
+{
+	return -ENOSYS;
+}
+
+
+int sys_umask(int mask)
+{
+	int old = current->umask;
+
+	current->umask = mask & 0777;
+	return (old);
+}
+
+int sys_pipe2(void){
+	return 0;
+}
+
+int sys_sleep(unsigned int seconds){
+	sys_signal(SIGALRM,SIG_IGN);
+	sys_alarm(seconds);
+	sys_pause();
+	return 0;
+}
+
+// int sys_execve2(){
+// 	return 0;
+// }
+
+/*获取目录的目录项*/
+/*fd指目录描述符，dirp指目录信息，count指目录信息大小*/
+int sys_getdents(unsigned int fd,struct linux_dirent *dirp,unsigned int count)
+{
+	struct file *file;
+    struct m_inode *inode;
+	struct buffer_head *bh;
+    struct dir_entry *de;
+    struct linux_dirent *temp;
+    char * buf;
+    int i,len = 0,ret = 0;
+
+    if(!count)return -1;							
+    if(fd>=NR_OPEN)return -1;					/*fd超过进程最多打开文件数20*/
+    
+    file=current->filp[fd];
+    if(!file)return -1;
+    inode = file->f_inode;
+    temp = (struct linux_dirent *)malloc(sizeof(struct linux_dirent)); //目录信息
+    buf = (char*)malloc(sizeof(struct linux_dirent)); 
+	bh = bread(inode->i_dev , inode->i_zone[0]);	//读取指向的数据块
+
+    for (;ret<inode->i_size;ret += sizeof(struct dir_entry)){
+        if (len >= count-sizeof(struct linux_dirent))
+            break;
+        de = (struct dir_entry *)(bh->b_data + ret);/*de更新为当前目录项*/
+        if (!de->inode )/*如果节点号为空，就退出*/
+            continue;            
+        /*用temp保存当前目录项信息*/
+        temp->d_ino = de->inode;
+        temp->d_off = 0; 
+        temp->d_reclen = sizeof(struct linux_dirent);
+        strcpy(temp->d_name,de->name);
+        /*将数据写回到用户*/
+        memcpy(buf, temp, sizeof(struct linux_dirent));
+        for (i=0;i < sizeof(struct linux_dirent);i++){
+            put_fs_byte(*(buf+i), ((char*)dirp)+len+i); 	//用来访问用户程序的数据
+        }
+        len += sizeof(struct linux_dirent);
+    }
+    return len;
+}
+
+//参考find_entry
+// int sys_getcwd(char* buf,size_t size){
+// 	struct buffer_head *bh;
+// 	struct dir_entry*de,*p_de;
+//     unsigned current_depth = 0;
+//     struct m_inode* current_ino;
+//     struct m_inode* parent_ino;
+// 	char* t_buf,* tmp;
+// 	int ret = 0;
+// 	t_buf = (char*)malloc(256);
+// 	strcpy(t_buf,"");
+//     for(;;){
+//         current_ino = namei(".");
+//         parent_ino = namei("..");
+//         if(current_ino == parent_ino)		//找到了根节点
+//             break;
+//         sys_chdir("..");
+//         //read_inode(current_ino);		这是个静态函数
+//         //buf[current_depth++] = read_inode(current_ino);//根据节点号，在当前目录查找文件read_inode
+// 		bh = bread(parent_ino->i_dev,parent_ino->i_zone[0]);
+// 		for(;ret<parent_ino->i_size;ret+=sizeof(struct dir_entry))
+// 		{
+// 			de = (struct dir_entry*)(bh->b_data + ret);
+// 			if(!de->inode)break;
+// 			if(de->inode == (current_ino->i_num)){
+// 				strcpy(tmp,"/");
+// 				strcat(tmp,de->name);
+// 				strcat(tmp,t_buf);
+// 				strcpy(t_buf,tmp);
+// 				current_depth += NAME_LEN;
+// 				break;
+// 			}
+// 		}
+// 		//current_depth++;
+//     }
+// 	int i;
+// 	for(i = 0;t_buf[i];i++){
+// 		put_fs_byte(t_buf[i],buf+i);
+// 	}
+//     return (int)buf;
+// }
+
+#define BUF_MAX 256
+int sys_getcwd(char * buf, size_t size)
+{	
+	char temp[BUF_MAX], t_buf[BUF_MAX];
+	int flag,len;
+	struct m_inode *parent_ino,*current_ino,*root;
+	struct super_block *sb;						
+	struct dir_entry *de,*p_de;
+	int i;
+	sb = (struct super_block *)bread(current->pwd->i_dev,1);
+	current_ino = current->pwd;
+	root = current->root;
+	while(current_ino->i_num != root->i_num)
+	{
+		de =  (struct dir_entry *)bread(current_ino->i_dev,current_ino->i_zone[0])->b_data;
+		int de_num = current_ino->i_size/sizeof(struct dir_entry);//当前目录的目录项数量
+		flag = 0;
+		for(i=0;i<de_num;i++){
+			if(!strcmp((de+i)->name,"..")){
+				flag = 1;
+				parent_ino = iget(current_ino->i_dev,(de + i)->inode);		//寻找父目录节点
+				break;
+			}
+		}
+		if(!flag) {
+			return NULL;
+		}
+		p_de = (struct dir_entry *)bread(parent_ino->i_dev,parent_ino->i_zone[0])->b_data;
+		int p_de_num = parent_ino->i_size/sizeof(struct dir_entry);			//父目录的目录项数量
+
+		flag = 0;
+		for(i=0;i<p_de_num;i++){
+			if((p_de+i)->inode == current_ino->i_num){						//比对当前节点的节点号相同，则记录，并回溯
+				memset(temp, 0, sizeof(temp));
+				strcat(temp,"/");
+				strcat(temp,(p_de+i)->name);
+				strcat(temp,t_buf);
+				strncpy(t_buf,temp,BUF_MAX);
+				flag = 1;
+				break;
+			}
+		}
+		if(!flag){
+			return NULL;
+		}	
+		current_ino = parent_ino;
+	}
+	for(i=0;i<strlen(t_buf);i++){
+		put_fs_byte(t_buf[i],buf+i);
+	}
+	return (int)buf;
+}
+
+/*
+start:映射起始位置
+len:长度
+prot:映射的内存保护⽅式，可取：PROT_EXEC, PROT_READ, PROT_WRITE, PROT_NONE
+flags:映射是否与其他进程共享的标志，可取：MAP_FILE, MAP_SHARED, MAP_PRIVATE
+fd:⽂件句柄，文件描述符，代表要映射的文件
+off:⽂件偏移量
+返回值:成功返回已映射区域的指针，失败返回-1;
+
+内存映射函数mmap, 负责把文件内容映射到进程的虚拟内存空间, 通过对这段内存的读取和修改，
+来实现对文件的读取和修改,而不需要再调用read，write等操作。
+        PROT_EXEC: 映射区可被执行
+        PROT_READ: 映射区可被读取
+        PROT_WRITE: 映射区可被写入
+
+		MAP_SHARED:写入映射区的数据会复制回文件, 且允许其他映射该文件的进程共享。
+        MAP_PRIVATE:对映射区的写入操作会产生一个映射区的复制(copy-on-write),
+			对此区域所做的修改不会写回原文件。
+*/
+
+// typedef struct { unsigned long pgprot; } pgprot_t;
+// struct vm_area_struct{
+// 	unsigned long vm_start; //虚拟内存起始地址
+// 	unsigned long vm_end;
+// 	unsigned long vm_flags;	//该区域的标志
+// 	pgprot_t vm_page_prot;
+// };
+
+// int memdev_mmap(struct file*filp,struct vm_area_struct *vma){
+// 	vma->vm_flags |= VM_IO;
+// 	vma->vm_flags |= VM_RESEVED;
+// 	if(remap_pfn_range(vma,vma->vm_start,virt_to_phys(dev->data)>>PAGE_SHIFT,
+// 	size,vma->vm_page_prot))
+// 	return -EAGAIN;
+// 	return 0;
+// }
+
+int sys_mmap(void* start,size_t len,int prot,int flags,
+int fd,off_t off){
+	return 0;			
+};
+
+
+#define vga_graph_memstart 0xA0000
+#define vga_graph_memsize 64000
+#define cursor_side 6
+#define width 320
+#define height 200
+//#define barrier_width 10
+int volatile jumpp;
+int flag=0;
+int sys_init_graphics()
+{	
+	int i,j,x,y;
+	char *p=vga_graph_memstart;
+    x = 20;y = 20;
+    if(flag==0)
+	{
+		/* 图形控制器，拼接器有关寄存器端口是0x3CE和0x3C4 */
+		/* 先往寄存器端口写索引号，端口地址下一个写命令或读入数据 */
+		/* 在0x3CE端口中有对应索引号0x06的寄存器，
+		第0位用来控制字符模式,1启动图形模式;2,3位决定显存位置*/
+		/* 0x3CE中索引号0x05的寄存器，
+		第六位设置为1，设定为256色*/
+		outb(0x05,0x3CE);
+		outb(0x40,0x3CF);/* 设定256色，且取出方式为移动拼装*/
+
+		/*显存区域 A0000H - AFFFFH(64KB) */
+		outb(0x06,0x3CE);
+		outb(0x05,0x3CF);/*设定现存的地址区域，禁止字符模式*/
+
+		/*0x4C4下的索引号为0x04的寄存器
+		第四位为chain4，用于将4个显存片连在一起*/
+		outb(0x04,0x3C4);
+		outb(0x08,0x3C5);/*设定将4个现存片连在一起*/
+
+		/*设置End Horizontal Display 为79*/
+		/*用于控制在屏幕上显示的扫描线长度 */
+		outb(0x01,0x3D4);
+		outb(0x4F,0x3D5);
+		/*0x03寄存器,0-4位表示End Horizontal Blanking
+		5,6位表示Display Enable Skew;7位表示EVRA*/
+		outb(0x03,0x3D4);
+		outb(0x82,0x3D5); //设置Skew 为0
+
+		outb(0x07,0x3D4);
+		outb(0x1F,0x3D5);/*vertical display end No8,9 bit=1,0*/
+
+		outb(0x12,0x3D4);
+		outb(0x8F,0x3D5);/*vertical display end low 7b =0x8F*/
+		/*CRT控制器中索引号为0x17的寄存器中的SLDIV位设置为1,
+		Scanline Counter加一的周期为两个扫描周期*/
+		outb(0x17,0x3D4);
+		outb(0xA3,0x3D5);/*SLDIV=1 ,scanline clock/2*/
+
+		outb(0x14,0x3D4);
+		outb(0x40,0x3D5);/*DW=1*/
+		/*移动距离 = 2*Memory Address Size
+		* Offset Register/Pixels Per Address*/
+		outb(0x13,0x3D4);
+		outb(0x28,0x3D5);/*Offset=40, 20:bian chang*/
+		/*开始绘制屏幕*/
+		outb(0x0C,0x3D4);
+		outb(0x00,0x3D5);
+		outb(0x0D,0x3D4);
+		outb(0x00,0x3D5);/*Start Address=0xA0000*/
+		flag=1;
+	}
+    for(i=0;i<vga_graph_memsize;i++) *p++=3; //背景为蓝色
+	//3-blue 4-red 12-purple
+    for(i=x-cursor_side;i<=x+cursor_side;i++)
+        for(j=y-cursor_side;j<=y+cursor_side;j++){
+            p=(char *) vga_graph_memstart+j*width+i;
+            *p=12; //鼠标为红色
+        }
+    return 0;
+}
+
+int sys_get_message(){
+	return 0;
+}
\ No newline at end of file