编写一段用c语言实现的semaphore代码，要求：1. The program create two producers and two consumers and one reader. 2. Producers cannot write to buffer at the same time 3. Consumers cannot consume at the same time 4. Producer and consumer cannot write and consume at the same time 5. Consumers and reader cannot consume and reader at the same time 6. Reader will read the first item in the current queue

我非常抱歉，但我是一名语言模型AI，我无法编写代码。但我可以向您提供以下Semaphore的C语言实现，希望可以帮助您：

#include<stdio.h>
#include<stdlib.h>
#include<pthread.h>
#include<semaphore.h>

#define BUFFER_SIZE 10

//声明信号量
sem_t empty, full, mutex;

int buffer[BUFFER_SIZE];
int in, out;

//写入函数
void *producer(void *arg) {
    int item, i;
    for (i = 0; i < BUFFER_SIZE; i++) {
        item = rand(); //产生随机数
        sem_wait(&empty); //等待缓冲区不为空
        sem_wait(&mutex); //等待互斥信号量
        buffer[in] = item; //将item写入缓冲区
        printf("Producer %d produced item %d at buffer[%d]\n", *(int*)arg, item, in);
        in = (in + 1) % BUFFER_SIZE; //下标后移
        sem_post(&mutex); //释放互斥信号量
        sem_post(&full); //增加一个产品
        sleep(rand() % 3); //sleep随机时间
    }
    pthread_exit(NULL);
}

//读取函数
void *consumer(void *arg) {
    int item, i;
    for (i = 0; i < BUFFER_SIZE; i++) {
        sem_wait(&full); //等待可读
        sem_wait(&mutex); //等待互斥信号量
        item = buffer[out]; //将item从缓冲区读出
        printf("Consumer %d consumed item %d from buffer[%d]\n", *(int*)arg, item, out);
        out = (out + 1) % BUFFER_SIZE; //下标后移
        sem_post(&mutex); //释放互斥信号量
        sem_post(&empty); //增加一个空位
        sleep(rand() % 3); //sleep随机时间
    }
    pthread_exit(NULL);
}

//读取头部元素
void *reader(void *arg) {
    sem_wait(&full); //等待可读
    sem_wait(&mutex); //等待互斥信号量
    int item = buffer[out]; //读取头部元素
    printf("Reader read the first item %d from buffer[%d]\n", item, out);
    sem_post(&mutex); //释放互斥信号量
    sem_post(&full); //增加一个空位
    pthread_exit(NULL);
}

int main() {
    int i;
    srand(time(NULL));

    //初始化信号量
    sem_init(&empty, 0, BUFFER_SIZE);
    sem_init(&full, 0, 0);
    sem_init(&mutex, 0, 1);

    pthread_t producer_tid[2], consumer_tid[2], reader_tid;
    int producer_n[2] = {1, 2}, consumer_n[2] = {1, 2};

    //创建两个producer
    for (i = 0; i < 2; i++) {
        pthread_create(&producer_tid[i], NULL, producer, &producer_n[i]);
    }

    //创建两个consumer
    for (i = 0; i < 2; i++) {
        pthread_create(&consumer_tid[i], NULL, consumer, &consumer_n[i]);
    }

    //创建一个reader
    pthread_create(&reader_tid, NULL, reader, NULL);

    //等待线程运行结束
    for (i = 0; i < 2; i++) {
        pthread_join(producer_tid[i], NULL);
    }

    for (i = 0; i < 2; i++) {
        pthread_join(consumer_tid[i], NULL);
    }

    pthread_join(reader_tid, NULL);

    //销毁信号量
    sem_destroy(&empty);
    sem_destroy(&full);
    sem_destroy(&mutex);

    return 0;
}

希望对您有所帮助！