H. A Cache Simulator

最新推荐文章于 2024-02-03 17:58:39 发布

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最新推荐文章于 2024-02-03 17:58:39 发布

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原文链接：http://www.cnblogs.com/Pretty9/p/7592984.html

本文介绍了一款基于Direct Mapped方式的缓存模拟器程序设计。该程序用于模拟1KB大小、每块16B的Cache，在256MB主存中运行，并通过输入地址报告命中或未命中情况。

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Cache memories have been used widely in current microprocessor systems. In this problem, you are asked to write a program for a cache simulator. The cache has the following metrics:

1. The cache size is 1 KB (K-byte).

2. The cache uses the direct mapped approach.

3. The cache line size is 16 bytes.

4. The cacheable memory size is 256MB.

Your program will report a hit or miss when an address is given to the cache simulator. This is often called trace simulation. Initially, all of the cache lines are in the invalid state. When a memory line is first brought into the cache, the allocated cache entry transits into the valid state. Assume that a miss causes the filling of a whole cache line.

Input Format

Up to

Output Format

Report either

样例输入

AAAA000
00010B2
00010BA
END

样例输出

Miss
Miss
Hit
Hit ratio = 33.33%

题目来源

2017 ACM-ICPC 亚洲区（南宁赛区）网络赛

题意：

模拟一个Cache， Cache的大小是1KB，每一块大小是16B，一共64块，采用direct mapped方式，主存大小是256MB；

思路：

因为计组成原理还没学到这，就现场学习了一下，有关direct mapped方式可以参考https://wenku.baidu.com/view/7ea3d85e10661ed9ad51f3f3.html?from=search，只要理解了direct mapped方式之后这题就好写了，用公式建立主存和Cache之间的联系，Cache一共64块，公式就是I = （address / 16）% 64；

代码：

#include<iostream>
#include<cstring>
#include<cstdio>
#include<string>
#include<map>

using namespace std;

const int M = 16 + 5;

map<int, string> mp;
char ch[M];

int main(){
    int total = 0, hit = 0;
    while(scanf("%s", ch) == 1 && strcmp(ch, "END")){
        int sum = 0;
        sscanf(ch, "%x", &sum);
        total ++;
        int I = (sum / 16) % 64;
        ch[6] = '\0';
        if(mp[I] == ch){
            hit ++;
            printf("Hit\n");
        }else{
            mp[I] = ch;
            printf("Miss\n");
        }
    }
    printf("Hit ratio = %.2f%%\n",double(hit*100.0/ total));
}