One potential implementation of the case described in IP_344 is switching the switch to "Don't Forward" mode as quickly as possible after a reset of the central processing unit in the ECU, checking, and then possibly correcting, the switch configuration, and then disabling "Don't Forward" mode once again. One benefit of this sample application is that unnecessary link break-downs are avoided.怎么理解

这段话是在讨论当ECU重置后，层2以太网交换机的一种潜在实现方式。这种实现方式是尽快将交换机切换到“不转发”模式，然后检查和可能更正交换机配置，最后再次禁用“不转发”模式。这样做的好处是避免了不必要的链路中断。换句话说，这种实现方式可以最小化交换机重置对通信的影响，使通信在最短的时间内恢复正常，避免了不必要的中断或故障。

相关问题

7-3 Score Processing 分数 10 作者 翁恺 单位 浙江大学 Write a program to process students score data. The input of your program has lines of text, in one of the two formats: Student's name and student id, as <student id>, <name>, and Score for one student of one course, as <student id>, <course name>, <marks>. Example of the two formats are: 3190101234, Zhang San 3190101111, Linear Algebra, 89.5 Comma is used as the seperator of each field, and will never be in any of the fields. Notice that there are more than one word for name of the person and name of the course. To make your code easier, the score can be treated as double. The number of the students and the number of the courses are not known at the beginning. The number of lines are not known at the beginning either. The lines of different format appear in no order. One student may not get enrolled in every course. Your program should read every line in and print out a table of summary in .csv format. The first line of the output is the table head, consists fields like this: student id, name, <course name 1>, <course name 2>, ..., average where the course names are all the courses read, in alphabet order. There should be one space after each comma. Then each line of the output is data for one student, in the ascended order of their student id, with score of each course, like: 3190101234, Zhang San, 85.0, , 89.5, , , 87.3 For the course that hasn't been enrolled, leave a blank before the comma, and should not get included in the average. The average has one decimal place. There should be one space after each comma. And the last line of the output is a summary line for average score of every course, like: , , 76.2, 87.4, , , 76.8 All the number output, including the averages have one decimal place. Input Format As described in the text above. Output Format As described in the text above. The standard output is generated by a program compiled by gcc, that the round of the first decimal place is in the "gcc way". Sample Input 3180111435, Operating System, 34.5 3180111430, Linear Algebra, 80 3180111435, Jessie Zhao 3180111430, Zhiwen Yang 3180111430, Computer Architecture, 46.5 3180111434, Linear Algebra, 61.5 3180111434, Anna Teng Sample Output student id, name, Computer Architecture, Linear Algebra, Operating System, average 3180111430, Zhiwen Yang, 46.5, 80.0, , 63.2 3180111434, Anna Teng, , 61.5, , 61.5 3180111435, Jessie Zhao, , , 34.5, 34.5 , , 46.5, 70.8, 34.

很好，这是一道关于学生成绩数据处理的编程题。下面是我的解答：

#include <iostream>
#include <vector>
#include <map>
#include <algorithm>
#include <iomanip>

using namespace std;

int main() {
    map<string, string> name_map; // 学生姓名字典
    map<string, vector<pair<string, double>>> score_map; // 学生成绩字典
    map<string, double> sum_map; // 课程成绩和字典
    map<string, int> cnt_map; // 课程成绩个数字典
    string line; // 输入的一行数据
    while (getline(cin, line)) {
        int pos1 = line.find(", "); // 第一个逗号的位置
        int pos2 = line.find(", ", pos1 + 2); // 第二个逗号的位置
        string id = line.substr(0, pos1); // 学生 ID
        string key = line.substr(pos2 + 2); // 课程名或学生姓名
        if (key.find('.') != string::npos) { // 如果是学生成绩
            double score = stod(key); // 成绩
            string course = line.substr(pos1 + 2, pos2 - pos1 - 2); // 课程名
            score_map[id].push_back(make_pair(course, score)); // 记录成绩
            sum_map[course] += score; // 累加成绩和
            cnt_map[course]++; // 记录个数
        } else {
            name_map[id] = key; // 记录学生姓名
        }
    }
    vector<string> courses; // 课程列表
    for (auto item : cnt_map) {
        courses.push_back(item.first);
    }
    sort(courses.begin(), courses.end()); // 课程按字母顺序排序
    cout << "student id, name, ";
    for (string course : courses) {
        cout << course << ", ";
    }
    cout << "average" << endl;
    for (auto item : score_map) {
        string id = item.first; // 学生 ID
        string name = name_map[id]; // 学生姓名
        cout << id << ", " << name << ", ";
        double sum = 0; // 成绩总和
        int cnt = 0; // 参加考试的课程数
        for (string course : courses) {
            bool found = false; // 是否参加考试
            for (auto score : item.second) {
                if (score.first == course) {
                    cout << fixed << setprecision(1) << score.second << ", ";
                    sum += score.second;
                    cnt++;
                    found = true;
                    break;
                }
            }
            if (!found) {
                cout << ", , ";
            }
        }
        if (cnt > 0) {
            cout << fixed << setprecision(1) << sum / cnt << endl;
        } else {
            cout << endl;
        }
    }
    cout << ", , ";
    for (string course : courses) {
        cout << fixed << setprecision(1) << (cnt_map[course] > 0 ? sum_map[course] / cnt_map[course] : 0) << ", ";
    }
    cout << endl;
    return 0;
}

这个程序的主要思路是使用四个字典来记录学生姓名、学生成绩、课程成绩和以及课程成绩个数，并且按照题目要求输出表格。

程序的详细注释如下：

1. 使用 `map<string, string> name_map` 记录每个学生的姓名，其中键为学生的 ID，值为学生的姓名。
2. 使用 `map<string, vector<pair<string, double>>> score_map` 记录每个学生的成绩，其中键为学生的 ID，值为包含课程名和成绩的一对 pair，使用 vector 来存储多个 pair。
3. 使用 `map<string, double> sum_map` 记录每门课程的成绩总和，其中键为课程名，值为成绩总和。
4. 使用 `map<string, int> cnt_map` 记录每门课程的成绩个数，其中键为课程名，值为成绩个数。
5. 使用 `getline(cin, line)` 读入每行输入，然后使用 `find()` 函数和 `substr()` 函数来解析每行输入。
6. 如果第二个逗号后面是数字，说明这是学生成绩，就把成绩和课程名记录在 `score_map`、`sum_map` 和 `cnt_map` 中。
7. 如果第二个逗号后面不是数字，说明这是学生姓名，就把学生姓名记录在 `name_map` 中。
8. 使用 `vector<string> courses` 记录所有参加考试的课程名，并且按字母顺序排序。
9. 使用 `cout` 输出表格头，先输出 `student id, name, `，然后按顺序输出所有课程名，最后输出 `average`。
10. 使用 `cout` 输出每个学生的成绩，先输出学生的 ID 和姓名，然后按顺序输出所有课程的成绩，如果某门课程没有参加考试，就留空，最后输出平均成绩。
11. 使用 `cout` 输出所有课程的平均成绩。

程序中使用了 `fixed` 和 `setprecision()` 函数来控制输出的小数点后一位。

Standard SPI Mode Standard SPI mode is selected when the Mode option in the Vivado IDE is set to Standard. The relevant parameters in this mode are: • Mode • Enable STARTUPE2 Primitive • Transaction Width • No. of Slaves • Frequency Ratio Send Feedback AXI Quad SPI v3.2 7 PG153 April 4, 2018 www.xilinx.com Chapter 1: Overview • Enable FIFO The properties of the core in standard SPI mode, including or excluding a FIFO, are described as: • The choice of inclusion of FIFO is based on the Enable FIFO parameter. FIFO Depth parameter is linked to Enable FIFO parameter. FIFO Depth limits the transmit and receive FIFO depth to 16 or 256 when FIFO is enabled. When FIFO is not enabled, the value of FIFO depth parameter is considered to be 0. A FIFO depth of 256 should be used because this is the most suitable depth in relation to the flash memory page size. • The valid values for the FIFO Depth option in this mode are 16 or 256 when FIFO is enabled through Enable FIFO parameter. When Enable FIFO is 0 and no FIFO is included in the core. Data transmission occurs through the single transmit and receive register. When FIFO Depth is 16 or 256, the transmit or receive FIFO is included in the design with a depth of 16 or 256 elements. The width of the transmit and receive FIFO is configured with the Transaction Width option. The AXI Quad SPI core supports continuous transfer mode. When configured as master, the transfer continues until the data is available in the transmit register/FIFO. This capability is provided in both manual and automatic slave select modes. As an example, during the page read command, the command, address, and number of data beats in the DTR must be set equal to the same number of data bytes intended to be read by the SPI memory. When the core is configured as a slave, if the slave select line (SPISEL) goes High (inactive state) during the data element transfer, the current transfer is aborted. If the slave select line goes Low, the aborted data element is transmitted again. The slave mode of the core is allowed only in the standard SPI mode.

标准SPI模式是在Vivado IDE中将Mode选项设置为Standard时选择的模式。该模式下的相关参数有：
• Mode（模式）
• Enable STARTUPE2 Primitive（启用STARTUPE2原语）
• Transaction Width（传输宽度）
• No. of Slaves（从设备数量）
• Frequency Ratio（频率比例）
• Enable FIFO（启用FIFO）

在标准SPI模式下，核心的属性包括是否包含FIFO等，具体描述如下：
• 是否包含FIFO的选择取决于Enable FIFO参数。FIFO Depth参数与Enable FIFO参数相关联。当启用FIFO时，FIFO Depth限制了传输和接收FIFO的深度为16或256。当未启用FIFO时，FIFO depth参数的值被认为是0。在与Flash存储器页面大小相关时，应使用256作为FIFO深度。
• 在这种模式下，FIFO Depth选项的有效值为16或256（仅当通过Enable FIFO参数启用FIFO时）。

当Enable FIFO为0且核心不包含FIFO时，数据传输通过单个发送和接收寄存器进行。当FIFO Depth为16或256时，设计中包含带有16或256个元素深度的发送或接收FIFO。发送和接收FIFO的宽度由Transaction Width选项进行配置。

AXI Quad SPI核支持连续传输模式。当配置为主设备时，传输将持续进行，直到发送寄存器/FIFO中的数据可用。这一功能在手动和自动从选模式下都提供。例如，在页读取命令期间，必须将命令、地址和DTR中的数据传输数量设置为与SPI存储器要读取的数据字节数相同。

当将核心配置为从设备时，如果从选线（SPISEL）在数据元素传输期间变为高电平（非活动状态），当前传输将被中止。如果从选线变为低电平，中止的数据元素将重新传输。核心的从设备模式仅允许在标准SPI模式下使用。