#include <ctype.h>
#include <stdlib.h>
#include <time.h>
#include <cstring>
#include <iostream>
using namespace std;
struct PCB {//进程控制块
    string name;//进程名
    int status;  // 1 就绪,  2 等待,3 完成,0 正在运行
    int waitreason;//等待原因
    int breakingpoint;//断点
};
PCB producer;//生产者进程
PCB consumer;//消费者进程
PCB* currp;//当前进程
int s1;//信号量：生产者可以往缓冲区放物品
int s2;//消费者可以从缓冲区拿
char c;//生产者生产的字符
char x;//消费者消费的字符
int pc;//程序计数器
int in;//生产者放的位置
int out;//消费者拿的位置
int pa[5];//生产者的程序
char B[10];//拿
int sa[5];//消费者程序
void init() {
    s1 = 10;
    s2 = 0;//初始化信号量
    out = 0;
    in = 0;//初始化生产者与消费者在缓冲区放的商品的位置
    producer.name = "producer";
    producer.status = 1;
    producer.waitreason = 0;
    producer.breakingpoint = 0;//pcb状态为就绪，断点为0
    consumer.name = "consumer";
    consumer.status = 1;
    consumer.waitreason = 0;
    consumer.breakingpoint = 0;//pcb状态为就绪，断点为0
    currp = &producer;//将现行进程设置为生产者进程
    pc = 0;//pc=0
    for (int i = 0; i <= 4; i++) {
        pa[i] = i;
        sa[i] = i;//初始化生产者程序与消费者程序
    }
}
void p(int& s, int p, PCB* pcb) {
    s = s - 1;
    cout << "mutex s" << p<<endl;
    if (s < 0) {
        pcb->status = 2;//等待状态
        pcb->waitreason = p;//等待的信号量是p
        cout << pcb->name << " begins waiting!\n";
    }
    else {
        cout << pcb->name << " doesn't need waiting!\n";
        pcb->status = 1;//将调用p(s)的进程置为就绪
    }
}
void v(int& s, int p, PCB* pcb) {
    s = s + 1;
    if (s <= 0) {
        if (producer.waitreason == p)
            producer.status = 1;
        else if (consumer.waitreason == p)
            consumer.status = 1;//将一个等待s信号量的进程置为就绪
        if (currp->name == "producer")
            cout << "consumer released!";
        else
            cout << "producer released!";
    }
    pcb->status = 1;//将调用V(s)的进程置为就绪
}
void printstate() {//打印当前状态
    cout << "*************************************************\n";
    cout << "current process" << currp->name << endl;
    cout << "producer breakingpoint" << producer.breakingpoint << endl;
    cout << "producer status" << producer.status << endl;
    cout << "producer waitreason" << producer.waitreason << endl;
    cout << "consumer breakingpoint" << consumer.breakingpoint << endl;
    cout << "consumer status" << consumer.status << endl;
    cout << "consumer waitreason" << consumer.waitreason << endl;
    cout << "*************************************************\n";
}
void exec() {//模拟处理器指令执行
    int i = pc;
    int j;
    int curq;
    cout << "current process " << currp->name << endl;
    if (currp->name == "producer") {//现行进程为生产者？
        j = pa[i];
        curq = 0;
    }
    else {
        j = sa[i];
        curq = 1;
    }
    pc = i + 1;
switch (j) {//按j转向各模拟指令对应的过程
    case 0:
        if (curq == 0) {//produce
            char pronum;
            cout << "please produce a char";
            cin >> pronum;
            c = pronum;
            cout << "produced!";
            currp->status = 1;
        }
        else
            p(s2, 2, currp);//p(s2)
        break;
    case 1:
        if (curq == 0)
            p(s1, 1, currp);//p(s1)
        else {//GET
            cout << "get goods!";
            x = B[out];
            out = (out + 1) % 10;
            cout << x << endl;
            currp->status = 1;
        }
        break;
    case 2:
        if (curq == 0) {//PUT
            cout << "put goods!";
            B[in] = c;
            in = (in + 1) % 10;
            cout << c << endl;
            currp->status = 1;
        }
        else
            v(s1, 1, currp);//V(s1)
        break;
    case 3:
        if (curq == 0)//V(s2)
            v(s2, 2, currp);
        else {//consume
            cout << "goods consumed!";
            cout << x << endl;
            currp->status = 1;
        }
        break;
    case 4://goto 0
        pc = 0;
        currp->status = 1;
        cout << "goto 0!";
        break;
    }
    if (producer.status != 3) {//模拟时采用人工选择的办法实现“生产者运行结束”的判断
        cout << "Has producer finished?Y/N";
        char st;
        cin >> st;
        if (st == 'Y')
            producer.status = 3;
    }
    return;
}
void cpuwork() {
    while (1) {
        currp->breakingpoint = pc;//当前进程pcb断点为pc
        if (consumer.status != 1 && producer.status != 1)
            return;//无就绪进程
        if (consumer.status == 1 && producer.status == 1) {
            srand(time(NULL));//随机选择一个就绪进程
            int randnum = rand() % 2;
            if (randnum >= 1)
                currp =& consumer;
            else
                currp =& producer; 
          /*
            int chooseprocess;
            cout << "choose a process:1.producer 2.consumer";
            cin >> chooseprocess;
            if (chooseprocess == 1)
                currp = &producer;
            else
                currp = &consumer;*/
        }
        else if (consumer.status == 1)
            currp = &consumer;
        else if(producer.status==1)
            currp = &producer;
        currp->status = 0;//将现行进程改为运行态
        pc = currp->breakingpoint;//现行进程pcb断点值赋值给pc
        exec();
    }
}
int main() {
    init();
    cpuwork();
    return 0;
}