操作系统随机分配代码c语言
时间: 2023-08-15 13:06:43 浏览: 51
操作系统通常会使用进程调度算法来分配CPU时间片,从而实现代码的随机分配。在C语言中,可以通过随机数生成函数来实现一定程度上的随机分配。例如,可以使用rand()函数生成随机数,并根据生成的随机数来执行不同的代码分支。具体实现方法可以参考以下示例代码:
```
#include <stdio.h>
#include <stdlib.h>
#include <time.h>
int main() {
srand(time(NULL)); // 初始化随机数生成器
int r = rand() % 2; // 生成0或1的随机数
if (r == 0) {
printf("执行代码分支1\n");
} else {
printf("执行代码分支2\n");
}
return 0;
}
```
上述代码中,使用srand()函数初始化随机数生成器,并使用rand()函数生成0或1的随机数。根据生成的随机数来执行不同的代码分支,从而实现了一定程度上的随机分配。
相关问题
操作系统 电梯调c语言
电梯调度是一个典型的操作系统问题,具体实现可以借助C语言来完成。以下是一个简单的电梯调度C语言代码示例:
```c
#include <stdio.h>
#include <stdlib.h>
#include <pthread.h>
#include <unistd.h>
#define FLOOR_NUM 20
#define ELEVATOR_NUM 3
#define MAX_PEOPLE 10
enum Direction {
UP,
DOWN
};
struct Person {
int id;
int start_floor;
int end_floor;
};
struct Elevator {
int id;
int cur_floor;
int num_people;
struct Person people[MAX_PEOPLE];
enum Direction direction;
pthread_mutex_t mutex;
pthread_cond_t cond;
pthread_t thread;
};
struct Building {
struct Elevator elevators[ELEVATOR_NUM];
pthread_mutex_t mutex;
};
void person_init(struct Person *person, int id, int start_floor, int end_floor) {
person->id = id;
person->start_floor = start_floor;
person->end_floor = end_floor;
}
void elevator_init(struct Elevator *elevator, int id) {
elevator->id = id;
elevator->cur_floor = 1;
elevator->num_people = 0;
elevator->direction = UP;
pthread_mutex_init(&elevator->mutex, NULL);
pthread_cond_init(&elevator->cond, NULL);
}
void building_init(struct Building *building) {
for (int i = 0; i < ELEVATOR_NUM; i++) {
elevator_init(&building->elevators[i], i);
}
pthread_mutex_init(&building->mutex, NULL);
}
void elevator_add_person(struct Elevator *elevator, struct Person *person) {
pthread_mutex_lock(&elevator->mutex);
while (elevator->num_people >= MAX_PEOPLE) { // 电梯已满
pthread_cond_wait(&elevator->cond, &elevator->mutex); // 等待
}
elevator->people[elevator->num_people++] = *person;
pthread_cond_signal(&elevator->cond); // 通知电梯已有人
pthread_mutex_unlock(&elevator->mutex);
}
void elevator_remove_person(struct Elevator *elevator, int index) {
pthread_mutex_lock(&elevator->mutex);
for (int i = index; i < elevator->num_people - 1; i++) {
elevator->people[i] = elevator->people[i + 1];
}
elevator->num_people--;
pthread_cond_signal(&elevator->cond); // 通知电梯已有空位
pthread_mutex_unlock(&elevator->mutex);
}
void elevator_move(struct Elevator *elevator) {
pthread_mutex_lock(&elevator->mutex);
if (elevator->direction == UP) {
for (int i = 0; i < FLOOR_NUM; i++) {
if (i < elevator->cur_floor) { // 已经经过的楼层
continue;
}
elevator->cur_floor = i;
printf("电梯%d上行到%d楼\n", elevator->id, elevator->cur_floor);
for (int j = 0; j < elevator->num_people; j++) { // 检查每个人是否到达目的地
if (elevator->people[j].end_floor == elevator->cur_floor) {
printf("电梯%d有人在%d楼下电梯\n", elevator->id, elevator->cur_floor);
elevator_remove_person(elevator, j);
j--;
}
}
if (elevator->cur_floor == FLOOR_NUM - 1) { // 到达顶层,改为下行
elevator->direction = DOWN;
break;
}
}
} else {
for (int i = FLOOR_NUM - 1; i >= 0; i--) {
if (i > elevator->cur_floor) { // 已经经过的楼层
continue;
}
elevator->cur_floor = i;
printf("电梯%d下行到%d楼\n", elevator->id, elevator->cur_floor);
for (int j = 0; j < elevator->num_people; j++) { // 检查每个人是否到达目的地
if (elevator->people[j].end_floor == elevator->cur_floor) {
printf("电梯%d有人在%d楼下电梯\n", elevator->id, elevator->cur_floor);
elevator_remove_person(elevator, j);
j--;
}
}
if (elevator->cur_floor == 0) { // 到达底层,改为上行
elevator->direction = UP;
break;
}
}
}
pthread_mutex_unlock(&elevator->mutex);
}
void *elevator_thread(void *arg) {
struct Elevator *elevator = (struct Elevator *)arg;
while (1) {
elevator_move(elevator);
usleep(1); // 等待一段时间,模拟电梯运行
}
return NULL;
}
void building_add_person(struct Building *building, struct Person *person) {
int elevator_id = rand() % ELEVATOR_NUM;
pthread_mutex_lock(&building->elevators[elevator_id].mutex);
elevator_add_person(&building->elevators[elevator_id], person);
pthread_mutex_unlock(&building->elevators[elevator_id].mutex);
}
void *person_thread(void *arg) {
struct Person *person = (struct Person *)arg;
printf("有人[%d]在%d楼等电梯\n", person->id, person->start_floor);
building_add_person((struct Building *)arg, person);
return NULL;
}
int main() {
srand(time(NULL)); // 随机数种子
struct Building building;
building_init(&building);
pthread_t person_threads[MAX_PEOPLE];
for (int i = 0; i < MAX_PEOPLE; i++) {
struct Person person;
person_init(&person, i, rand() % FLOOR_NUM, rand() % FLOOR_NUM);
pthread_create(&person_threads[i], NULL, person_thread, (void *)&building);
usleep(10000); // 等待一段时间,模拟人的到来
}
for (int i = 0; i < ELEVATOR_NUM; i++) {
pthread_create(&building.elevators[i].thread, NULL, elevator_thread, (void *)&building.elevators[i]);
}
for (int i = 0; i < MAX_PEOPLE; i++) {
pthread_join(person_threads[i], NULL);
}
for (int i = 0; i < ELEVATOR_NUM; i++) {
pthread_cancel(building.elevators[i].thread);
}
return 0;
}
```
以上代码实现了一个多线程的电梯调度,包括电梯的初始化、人员的加入和移除、电梯的移动等功能。在主函数中,我们使用多个线程模拟了多个人同时在楼层等电梯,通过调用`building_add_person`函数将人分配给随机选择的电梯。电梯运行的过程在`elevator_thread`函数中被模拟,通过调用`elevator_move`函数实现电梯的移动,每次移动后等待一段时间,模拟电梯的实际运行。最后,我们使用`pthread_cancel`函数取消电梯线程的运行。
需要注意的是,多线程程序中需要使用锁和条件变量来保证线程之间的同步和互斥,避免出现竞态条件等问题。在以上代码中,我们使用了`pthread_mutex_t`和`pthread_cond_t`等线程相关的函数来实现同步和互斥。
银行家算法C语言简单代码实现
以下是一个简单的C语言实现银行家算法的代码,它可以用于操作系统课程设计有关银行家算法的实现。该代码实现了银行家算法和随机分配算法,可以进行资源的申请和释放,并判断是否存在死锁情况。
```c
// 银行家算法C语言简单代码实现
#include <stdio.h>
#include <stdlib.h>
#include <stdbool.h>
#define MAX_PROCESS_NUM 10 // 最大进程数
#define MAX_RESOURCE_NUM 10 // 最大资源数
int available[MAX_RESOURCE_NUM]; // 可用资源数
int max[MAX_PROCESS_NUM][MAX_RESOURCE_NUM]; // 最大需求矩阵
int allocation[MAX_PROCESS_NUM][MAX_RESOURCE_NUM]; // 已分配矩阵
int need[MAX_PROCESS_NUM][MAX_RESOURCE_NUM]; // 需求矩阵
bool finish[MAX_PROCESS_NUM]; // 进程是否完成标志
// 初始化数据
void init_data(int process_num, int resource_num, int *available, int *max, int *allocation, int *need) {
int i, j;
for (i = 0; i < resource_num; i++) {
available[i] = *(available + i);
}
for (i = 0; i < process_num; i++) {
for (j = 0; j < resource_num; j++) {
max[i][j] = *(max + i * resource_num + j);
allocation[i][j] = *(allocation + i * resource_num + j);
need[i][j] = max[i][j] - allocation[i][j];
}
finish[i] = false;
}
}
// 判断是否存在死锁
bool is_deadlock(int process_num, int resource_num) {
int i, j, k;
bool flag;
int work[MAX_RESOURCE_NUM];
for (i = 0; i < resource_num; i++) {
work[i] = available[i];
}
for (i = 0; i < process_num; i++) {
if (!finish[i]) {
flag = true;
for (j = 0; j < resource_num; j++) {
if (need[i][j] > work[j]) {
flag = false;
break;
}
}
if (flag) {
for (k = 0; k < resource_num; k++) {
work[k] += allocation[i][k];
}
finish[i] = true;
i = -1;
}
}
}
for (i = 0; i < process_num; i++) {
if (!finish[i]) {
return true;
}
}
return false;
}
// 银行家算法
bool banker_algorithm(int process_num, int resource_num, int *available, int *max, int *allocation, int *need, int process_id, int *request) {
int i;
bool flag = true;
for (i = 0; i < resource_num; i++) {
if (request[i] > need[process_id][i] || request[i] > available[i]) {
flag = false;
break;
}
}
if (flag) {
for (i = 0; i < resource_num; i++) {
available[i] -= request[i];
allocation[process_id][i] += request[i];
need[process_id][i] -= request[i];
}
if (is_deadlock(process_num, resource_num)) {
for (i = 0; i < resource_num; i++) {
available[i] += request[i];
allocation[process_id][i] -= request[i];
need[process_id][i] += request[i];
}
return false;
} else {
return true;
}
} else {
return false;
}
}
// 随机分配算法
void random_algorithm(int process_num, int resource_num, int *available, int *max, int *allocation, int *need) {
int i, j, k;
int request[MAX_RESOURCE_NUM];
for (i = 0; i < process_num; i++) {
for (j = 0; j < resource_num; j++) {
request[j] = rand() % (need[i][j] + 1);
}
banker_algorithm(process_num, resource_num, available, max, allocation, need, i, request);
}
}
int main() {
int process_num = 5; // 进程数
int resource_num = 3; // 资源数
int available[] = {3, 3, 2}; // 可用资源数
int max[] = {
7, 5, 3,
3, 2, 2,
9, 0, 2,
2, 2, 2,
4, 3, 3
}; // 最大需求矩阵
int allocation[] = {
0, 1, 0,
2, 0, 0,
3, 0, 2,
2, 1, 1,
0, 0, 2
}; // 已分配矩阵
int need[MAX_PROCESS_NUM][MAX_RESOURCE_NUM]; // 需求矩阵
init_data(process_num, resource_num, available, max, allocation, need);
random_algorithm(process_num, resource_num, available, max, allocation, need);
return 0;
}
```