操作系统课程设计 基于DOS的多任务系统的实现

内容要求：

（1）用C语言完成线程的创建和撤销，并按先来先服务方式对多个线程进行调度。

（2）将线程调度算法修改为时间轮转算法，实现时间片轮转调度。

（3）改变时间片的大小，观察结果的变化。

（4）假设两个线程共用一软件资源（如某一变量，或某一数据结构），请用记录型信号量来实现对它的互斥访问。

（5）假设有两个线程共享一个可存放5个整数的缓冲，其中一个线程不停地计算1至50的平方，并将结果放入缓冲，另一个线程不断地从缓冲中取出结果，并将它们打印出来，请用记录型信号量来实现这一生产者和消费者的同步问题。

（6）实现消息缓冲通信。

代码运行环境：Turbo C

#include <alloc.h>#include <stdio.h>#include <string.h>#include <stdlib.h>#include <dos.h>/* 状态码常量定义 */#define FINISHED0/* 表示线程处于终止态或者TCB是空白状态 */#define RUNNING1/* 表示线程处于运行态 */#define READY2/* 表示线程处于就绪态 */#define BLOCKED3/* 表示线程处于阻塞态 */#define NTCB10/* NTCB是系统允许的最多任务数 */#define NTEXT20/* 文本大小 */#define NBUF5/* 缓冲区大小 */#define NSTACK 1024/* 私有栈大小 */#define GET_INDOS 0x34#define GET_CRIT_ERR 0x5d06char far *indos_ptr = 0;/* 该指针变量存放INDOS标志的地址 */char far *crit_err_ptr = 0;/* 该指针变量存放严重错误标志的地址 */int timecount = 0;int TL;/* time slice时间片 */int current = -1;/* 当前进程的tcb下标 */int n = 0;typedef int (far *codeptr)(void);/* 定义一个函数指针类型 */void interrupt(*old_int8)(void);/* 记录型信号量 */typedef struct{int value;struct TCB *wq;}semaphore;semaphore mutex = {1, NULL};semaphore mutexfb = {1, NULL};/* 缓冲区互斥信号量 */semaphore sfb = {NBUF, NULL};/* 计算信号量 */semaphore empty = {NBUF, NULL};semaphore full = {0, NULL};/* 消息缓冲区 */struct buffer{int id;int size;char text[NTEXT];struct buffer *next;}buf[NBUF], *freebuf;struct TCB{unsigned char *stack;/* 线程堆栈的起始位置 */unsigned ss;/* 堆栈段址 */unsigned sp;/* 堆栈指针 */char state;/* 线程状态，取值可以是FINISHED, RUNNING, READY, BLOCKED */char name[NTEXT];/* 线程的外部标识符 */struct buffer *mq;/* 接收线程的消息队列首指针 */semaphore mutex;/* 接收线程的消息队列的互斥信号量 */semaphore sm;/* 接收线程的消息队列的计数信号量，用于实现同步 */struct TCB *next;} tcb[NTCB];struct int_regs{unsigned bp, di, si, ds, es, dx, cx, bx, ax, ip, cs, flags, off, seg;};int intbuf[NBUF], buftemp;int in = 0, out = 0;void over();void destroy(int id);void wait(semaphore *sem);void signal(semaphore *sem);void block(struct TCB **qp);void wakeupFirst(struct TCB **qp);void send(char *receiver, char *a, int size);int receive(char *sender, char *b);/* InitDos()函数：功能是获得INDOS标志地址和严重错误标志的地址 */void InitDos(void){union REGS regs;struct SREGS segregs;/* 获得INDOS标志的地址 */regs.h.ah = GET_INDOS;/* intdosx(): Turbo C的库函数，其功能是调用DOS的INT21H中断 */intdosx(®s, ®s, &segregs);/* MK_FP(): 不是一个函数，只是一个宏 *//* 其功能是做段基址加上偏移地址的运算，也就是取实际地址。 */indos_ptr = MK_FP(segregs.es, regs.x.bx);/* 获得严重错误标志的地址 *//* 代码中用到的_osmajor、_osminor是Turbo C的全程变量， 其中前者为DOS版本号的主要部分，后者为版本号的次要部分。 */if(_osmajor < 3)crit_err_ptr = indos_ptr + 1;else if(_osmajor == 3 && _osminor == 0)crit_err_ptr = indos_ptr - 1;else{regs.x.ax = GET_CRIT_ERR;intdosx(®s, ®s, &segregs);crit_err_ptr = MK_FP(segregs.ds, regs.x.si);}}/* DosBusy(): 函数功能是获得Indos标志及严重错误标志的值，判断是否dos忙； *//* 如果返回值是1，表示dos忙； *//* 如果返回值是0，表示dos不忙； *//* 如果返回值是-1，表示还没有调用InitDos() */int DosBusy(void){if(indos_ptr && crit_err_ptr)return (*indos_ptr || *crit_err_ptr);elsereturn -1;/* InitDos() hasn't been called */}/* 初始化tcb */void initTCB(){int i;for(i = 0; i < NTCB; i++){tcb[i].name[0] = '\0';tcb[i].stack = NULL;tcb[i].state = FINISHED;tcb[i].mq = NULL;tcb[i].mutex.value = 1;tcb[i].mutex.wq = NULL;tcb[i].sm.value = 0;tcb[i].sm.wq = NULL;tcb[i].next = NULL;}}void f1(void){long i,j,k;for(i=0;i<1000;i++){putchar('a');for(j=0;j<1000;j++)for(k=0;k<100;k++);}}void f2(void){long i,j,k;for(i=0;i<100;i++){putchar('b');for(j=0;j<1000;j++)for(k=0;k<100;k++);}}void f3(void){long i,j,k;for(i=0;i<1000;i++){putchar('c');for(j=0;j<1000;j++)for(k=0;k<100;k++);}}void f4(){int i;for(i = 0; i < 10; i++){wait(&mutex);n++;printf(" %d", n);signal(&mutex);sleep(1);}}void f5(){int i;for(i = 0; i < 5; i++){wait(&mutex);n--;printf(" %d ", n);signal(&mutex);sleep(1);}}void prdc(){int tmp, i;for(i = 1; i <= 10; i++){tmp = i * i;printf("prdc %d\n", tmp);wait(&empty);wait(&mutex);intbuf[in] = tmp;in = (in + 1) % NBUF;/*printf("in: %d\n", in);*/signal(&mutex);signal(&full);}}void cnsm(){int tmp, i;for(i = 1; i <= 10; i++){wait(&full);wait(&mutex);tmp = intbuf[out];out = (out + 1) % NBUF;/*printf("out: %d\n", out);*/signal(&mutex);signal(&empty);printf("Out %d: %d\n", i, tmp);sleep(2);}}void sender(void){int i,j;char a[10];loop:for(i=0;i<10;i++){strcpy(a,"message");a[7]='0'+n;a[8]=0;send("receiver",a,strlen(a));printf("sender:Message \"%s\"  has been sent\n",a);n++;}receive("receiver",a);if (strcmp(a,"ok")!=0){printf("Not be committed,Message should be resended!\n");/*接收进程没确认,需重新发送消息*/goto loop;}elseprintf("Committed,Communication is finished!\n");/*发送者得到接收者的确认,通信结束*/}void receiver(void){int i,j,size;char b[10];for(i=0;i<10;i++){b[0]=0;while((size=receive("sender",b))==-1);printf("receiver: Message is received--");for(j=0;j<size;j++)putchar(b[j]);printf("\n");}strcpy(b,"ok");send("sender",b,3);/* 发送确认消息 */}int create(char *name, codeptr code, int stck){struct int_regs far *r;int i, id = -1;for(i = 0; i < NTCB; i++){if(tcb[i].state == FINISHED){id = i;break;}}if(id == -1)return -1;disable();tcb[id].stack = (unsigned char *)malloc(stck);r = (struct int_regs *)(tcb[id].stack + stck);r--;tcb[id].ss=FP_SEG(r);tcb[id].sp=FP_OFF(r);r->cs = FP_SEG(code);r->ip = FP_OFF(code);r->es = _DS;r->ds = _DS;r->flags = 0x200;r->seg = FP_SEG(over);r->off = FP_OFF(over);tcb[id].state = READY;strcpy(tcb[id].name, name);enable();}void interrupt swtch(){int loop = 0;disable();tcb[current].ss = _SS;tcb[current].sp = _SP;if(tcb[current].state == RUNNING)tcb[current].state = READY;while(tcb[++current].state != READY && loop++ < NTCB - 1)if(current == NTCB)current = 0;if(tcb[current].state != READY)current = 0;_SS = tcb[current].ss;_SP = tcb[current].sp;tcb[current].state = RUNNING;timecount = 0;enable();}void destroy(int id){disable();free(tcb[id].stack);tcb[id].stack = NULL;tcb[id].state = FINISHED;printf("\nProcess %s terminated\n", tcb[id].name);tcb[id].name[0] = '\0';enable();}void over(){destroy(current);swtch();}int finished(){int i;for(i = 1; i < NTCB; i++)if(tcb[i].state != FINISHED)return 0;return 1;}void free_all(void){int i;for(i=0;i<NTCB;i++){if(tcb[i].stack){tcb[i].name[0]='\0';tcb[i].state=FINISHED;free(tcb[i].stack);tcb[i].stack=NULL;}}}void interrupt new_int8(){(*old_int8)();timecount++;if(timecount < TL)return ;if(DosBusy())return ;swtch();}void wait(semaphore *sem){struct TCB **qp;disable();sem->value--;if(sem->value < 0){qp = &(sem->wq);block(qp);}enable();}void signal(semaphore *sem){struct TCB **qp;disable();qp = &(sem->wq);sem->value++;if(sem->value <= 0){wakeupFirst(qp);}enable();}void block(struct TCB **qp){int id;struct TCB *tcbtmp;id = current;tcb[id].state = BLOCKED;if((*qp) == NULL)(*qp) = &tcb[id];else{tcbtmp = *qp;while(tcbtmp->next != NULL)tcbtmp = tcbtmp->next;tcbtmp->next = &tcb[id];}tcb[id].next = NULL;swtch();}void wakeupFirst(struct TCB **qp){struct TCB *tcbtmp;if((*qp) == NULL)return ;tcbtmp = *qp;*qp = (*qp)->next;tcbtmp->state = READY;tcbtmp->next = NULL;}void initBuf(){int i;for(i = 0; i < NBUF - 1; i++){buf[i].next = &buf[i+1];}buf[i].next = NULL;freebuf = &buf[0];}struct buffer *getbuf(){struct buffer *buff;buff = freebuf;freebuf = freebuf->next;return buff;}void insert(struct buffer **mq, struct buffer *buff){struct buffer *temp;if(buff == NULL)return ;buff->next = NULL;if(*mq == NULL)*mq = buff;else{temp = *mq;while(temp->next != NULL)temp = temp->next;temp->next = buff;}}void send(char *receiver, char *a, int size){struct buffer *buff;int i, id = -1;disable();for(i = 0; i < NTCB; i++){if(strcmp(receiver, tcb[i].name) == 0){id = i;break;}}if(id == -1){printf("Error: Receiver not exist.\n");enable();return ;}wait(&sfb);wait(&mutexfb);buff = getbuf();signal(&mutexfb);buff->id = current;buff->size = size;buff->next = NULL;strcpy(buff->text, a);wait(&tcb[id].mutex);insert(&tcb[id].mq, buff);signal(&tcb[id].mutex);signal(&tcb[id].sm);enable();}struct buffer *remov(struct buffer **mq, int sender){struct buffer *buff, *p, *q;q = NULL;p = *mq;while((p->next != NULL) && (p->id != sender)){q = p;p = p->next;}if(p->id == sender){buff = p;if(q == NULL)*mq = buff->next;elseq->next = buff->next;buff->next = NULL;return buff;}elsereturn NULL;}int receive(char *sender, char *b){int i, id = -1;struct buffer *buff;disable();for(i = 0; i < NBUF; i++){if(strcmp(sender, tcb[i].name) == 0){id = i;break;}}if(id == -1){enable();return -1;}wait(&tcb[current].sm);wait(&tcb[current].mutex);buff = remov(&(tcb[current].mq), id);signal(&tcb[current].mutex);if(buff == NULL){signal(&tcb[current].sm);enable();return -1;}strcpy(b, buff->text);wait(&mutexfb);insert(&freebuf, buff);signal(&mutexfb);signal(&sfb);enable();return buff->size;}void main(){int select = -1;InitDos();initTCB();old_int8 = getvect(8);strcpy(tcb[0].name, "main");tcb[0].state = RUNNING;current = 0;while(select != 0){do{clrscr();printf("0. Exit\n");printf("1. First come first serve\n");printf("2. Time slice\n");printf("3. Change TL, see what would change\n");printf("4. Exclusively assess\n");printf("5. Producer and consumer SYNC problem\n");printf("6. Message buffer communication\n");scanf("%d", &select);}while(select < 0 || select > 7);switch(select){case 1:create("f1", (codeptr)f1, NSTACK);create("f2", (codeptr)f2, NSTACK);clrscr();printf("\ncreate f1 and f2\n");printf("f1 prints 1000 a\n");printf("f2 prints 100 b\n");swtch();getch();break;case 2:TL = 1;printf("Time slice = 1\n\n");getch();create("f1", (codeptr)f1, NSTACK);create("f2", (codeptr)f2, NSTACK);create("f3", (codeptr)f3, NSTACK);clrscr();printf("\ncreate f1, f2, f3\n");printf("f1 prints 1000 a\n");printf("f2 prints 100 b\n");printf("f3 prints 1000 c\n");setvect(8, new_int8);swtch();getch();break;case 3:printf("Enter new time slice: ");scanf("%d", &TL);printf("Time slice = %d\n\n", TL);getch();create("f1", (codeptr)f1, NSTACK);create("f2", (codeptr)f2, NSTACK);create("f3", (codeptr)f3, NSTACK);clrscr();printf("\ncreate f1, f2, f3\n");printf("f1 prints 1000 a\n");printf("f2 prints 100 b\n");printf("f3 prints 1000 c\n");setvect(8, new_int8);swtch();getch();break;case 4:n = 0;TL = 1;create("f4", (codeptr)f4, NSTACK);create("f5", (codeptr)f5, NSTACK);printf("\ncreate f4, f5\n");printf("f4 increase n 1 each time\n");printf("f5 decrease n 1 each time\n");setvect(8, new_int8);swtch();getch();break;case 5:TL = 4;create("prdc", (codeptr)prdc, NSTACK);create("cnsm", (codeptr)cnsm, NSTACK);printf("prdc\n");printf("cnsm\n");getch();setvect(8, new_int8);swtch();getch();break;case 6:initBuf();create("sender",(codeptr)sender,NSTACK);create("receiver",(codeptr)receiver,NSTACK);printf("sending\n");getch();TL = 1;setvect(8, new_int8);swtch();getch();break;default: select = 0;}while(!finished());setvect(8, old_int8);}free_all();tcb[0].name[0] = '\0';tcb[0].state = FINISHED;printf("\nMulti task system terminated.\n");getch();}