计算机组成原理变形补码计算题_原码反码补码例题详解

#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
int question = 0;
string fu(string str) {
    if (str[0] == '0') {
        str.replace(0, 2, "11");
    } else {
        str.replace(0, 2, "00");
    }
    return str;
}
string fanMa(string str) {
    for (int i = 2; i < str.length(); i++) {
        if (str[i] == '0') {
            str[i] = '1';
        } else {
            str[i] = '0';
        }
    }
    return str;
}
// 正数的原码反码补码都一样, 负数补码是反码+1
string buMa(string str) {
    if (str[0] == '1') {
        str = fanMa(str);
        int flag = 1; // 标记要进位1
        for (int i = str.length() - 1; i >= 0; i--) {
            if (str[i] == '0') {
                if (flag) {
                    flag = 0;
                    str[i] = '1';
                }
            } else if (str[i] == '1') {
                if (flag) {
                    str[i] = '0';
                }
            }
        }
    }
    return str;
}
string minus1(string str) {
    // 相当于找到最后一个1变成0，最后一个1前的0都变成1
    int flag = -1;
    for (int i = str.length() - 1; i >= 0; i--) {
        if (str[i] == '0') {
            if (flag) {
                str[i] = '1';
            }
        } else if (str[i] == '1') {
            if (flag) {
                flag = 0;
                str[i] = '0';
            }
        }
    }
    return str;
}
// 从补码转到原码
string B2Y(string str) {
    string res;
    if (str[0] == str[1]) {
        if (str[0] == '0') {
            res = " +";
            res += str.substr(2);
        } else {
            res = " -";
            res += minus1(str.substr(2));
            res = fanMa(res);
        }
    } else {
        if (str[0] == '0') {
            res = "+";
            res += str.substr(1);
        } else {
            res = "-";
            res += minus1(str.substr(1));
            res = fanMa(res);
        }
    }
    return res;
}
void checkOverFlow(string str) {
    if (str.substr(0, 2) == "01") {
        cout << "正溢出" << endl;
    } else if (str.substr(0, 2) == "10") {
        cout << "负溢出" << endl;
    } else {
        cout << "未溢出" << endl;
    }
}
// 输入X和Y的原码, 计算结果
string Cal(string X, string Y, char oper = '+') {
    printf("\n(%d)\n", ++question);
    X = buMa(X);
    cout << "[X]补:   " << X << endl;
    if (oper == '-') {
        Y = fu(Y);
    }
    Y = buMa(Y);
    if (oper == '-') {
        cout << "[-Y]补:  " << Y << endl;
    } else {
        cout << "[Y]补:   " << Y << endl;
    }
    int flag = 0; // 标记是否要进位
    for (int i = X.length() - 1; i >= 0; i--) {
        int cur = X[i] - '0' + Y[i] - '0' + flag;
        if (cur > 1) {
            flag = 1;
        } else {
            flag = 0;
        }
        if (cur & 1) {
            X[i] = '1';
        } else {
            X[i] = '0';
        }
    }
    printf("------------------\n");
    cout << "[X" << oper << "Y]补: " << X << endl;
    cout << " X" << oper << "Y   : " << B2Y(X) << endl;
    checkOverFlow(X);
    return X;
}

int main() {
    system("chcp 65001");
    cin.tie(0);
    cout.tie(0);
    // bitset<7> a(27);
    // string strX = a.to_string();
    Cal("0011011", "0000011");
    Cal("0011011", "1110101");
    Cal("0011011", "1110011", '-');
    return 0;
}