cache模拟器代码设计

一个基本的cache模拟器代码设计如下：

#include <iostream>
#include <vector>
#include <cmath>

using namespace std;

// 定义cache行的结构体
struct CacheLine {
    bool valid;  // 是否有效
    int tag;     // 标记位
};

class CacheSimulator {
public:
    CacheSimulator(int cacheSize, int blockSize, int associativity) {
        this->cacheSize = cacheSize;
        this->blockSize = blockSize;
        this->associativity = associativity;
        this->numBlocks = cacheSize / blockSize / associativity;
        this->numSets = numBlocks / associativity;
        this->offsetBits = log2(blockSize);
        this->indexBits = log2(numSets);
        this->tagBits = 32 - offsetBits - indexBits;

        cache.resize(numSets, vector<CacheLine>(associativity));
    }

    void access(int address) {
        int offset = address & (blockSize - 1);
        int index = (address >> offsetBits) & (numSets - 1);
        int tag = address >> (offsetBits + indexBits);

        for (int i = 0; i < associativity; i++) {
            if (cache[index][i].valid && cache[index][i].tag == tag) {
                cout << "Hit!" << endl;
                return;
            }
        }

        cout << "Miss!" << endl;

        // 找到一个空的cache行或者替换一个cache行
        for (int i = 0; i < associativity; i++) {
            if (!cache[index][i].valid) {
                cache[index][i].valid = true;
                cache[index][i].tag = tag;
                return;
            }
        }

        // 如果没有空的cache行，则替换最近最少使用的行
        int minCount = cache[index][0].count;
        int minIndex = 0;

        for (int i = 1; i < associativity; i++) {
            if (cache[index][i].count < minCount) {
                minCount = cache[index][i].count;
                minIndex = i;
            }
        }

        cache[index][minIndex].tag = tag;
        cache[index][minIndex].count = 0;
    }

private:
    int cacheSize;        // cache大小
    int blockSize;        // 块大小
    int associativity;    // 相联度
    int numBlocks;        // 块数
    int numSets;          // 组数
    int offsetBits;       // 块内偏移的位数
    int indexBits;        // 组索引的位数
    int tagBits;          // 标记位的位数

    vector<vector<CacheLine>> cache;    // cache数组
};

这个cache模拟器支持三种替换策略：直接映射、全相联和组相联。其中，直接映射的相联度为1，全相联的相联度为cache大小/块大小，组相联的相联度为指定的相联度。