CSAPP的缓存实验分为partA和partB

partA就是模拟一个缓存
难的不是处理缓存的思路，而是处理参数的思路，如何将参数、内容抽象成数据结构。

#include "cachelab.h"
#include <getopt.h>
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#define IDX(m,n,E) m * E + n
#define MAXSIZE 30
char input[MAXSIZE]; /* 保存每行的字符串 */

struct mCache{
	int valid;//有效位
	int tag;//标记位
	int count;//最近访问次数
};
typedef struct mCache Cache;
int hit_count = 0, miss_count = 0, eviction_count = 0;

/* 将 16 进制转为 10 进制数 */
int hextodec(char c);
/* 反转二进制的 b 位，可以不需要 */
/* int converse(int n, int b); */
/* 缓存加载 */
void Load(int count, unsigned int setindex, unsigned int tag,
			 double s_pow, unsigned int E,
          double b_pow, Cache *cache);

int main(int argc,char* argv[])
{  
	// const char *str = "Usage: ./csim [-hv] -s <num> -E <num> -b <num> -t "
    //                 "<file>\nOptions:\n  -h Print this help message.\n  -v "
    //                 "Optional verbose flag.\n  -s <num> Number of set index "
    //                 "bits.\n  -E <num> Number of lines per set.\n  -b <num> "
    //                 "Number of block offset bits.\n  -t <file> Trace file.\n\n"
    //                 "Examples :\n linux> ./csim -s 4 -E 1 -b 4 -t "
    //                 "traces/yi.trace\n linux>  ./csim -v -s 8 -E 2 "
    //                 "-b 4 -t traces/yi.trace\n ";
	int opt = 0;                      /* 保存参数 */
	unsigned int s = 0, E = 0, b = 0; /* 组的位数 每组行数 和 块数目的位数 */
	double s_pow = 0, b_pow = 0; /* 组数 块数 */
	char *t = "";                /* trace 文件 */

	while((opt = getopt(argc, argv, "s:E:-b:-t:")) != -1) {
		switch (opt) {
			case 's' :
				s = atoi(optarg);
				s_pow = 1 << s;/* 组数 */
				break;
			case 'E' :
				E = atoi(optarg);/* 每组行数 */
				break;
			case 'b':
				b = atoi(optarg);
				b_pow = 1 << b; /* 每行块数 */
				break;
			case 't':
				t = optarg; /* trace 文件 */
				break;
			default: /* '?' */
				fprintf(stderr, "Usage: %s [-hv] -s <num> -E <num> -b <num> -t <file>\n",
						argv[0]);
				exit(EXIT_FAILURE);			
		}
	}

	Cache *cache = (Cache*)malloc(sizeof(Cache) * s_pow * E);

	for(int i = 0; i < s_pow * E; ++i) {
		cache[i].valid = 0;
		cache[i].tag = 0;
		cache[i].count = 0;
	}
	FILE *fp = fopen(t, "r"); /* 打开 trace 文件 */
	int count = 0;            /* 可以当作时间的计数，用于每次访问缓存时更新缓存行的计数 */

	/* 分析 trace 文件的每一行 */
	while(fgets(input,MAXSIZE,fp)) {
		int op = 0; /* 需要访问缓存的次数 */
		unsigned int offset = 0, tag = 0,
						setindex = 0; /* 缓存行的块索引，tag 标记，组号 */
		char c;
		int cflag = 0;                      /* 是否有逗号的标记 */
		unsigned int address = 0; /* 访问缓存的地址 */
		count++;                            /* 计数 */

		for(int i = 0; (c = input[i]) && (c != '\n');++i) {
			if(c == ' ') continue;
			else if(c == 'I') {
				op = 0;
			}else if(c == 'L') {
				op = 1;
			}else if(c == 'S') {
				op = 1;
			}else if(c == 'M') {
				op = 2;
			}else if(c == ',') {
				cflag = 1;
			}else {
				if(cflag) {//逗号
					;
				}else {
					address = (address << 4) + hextodec(c);
				}
			}
		}
		//计算offset
		for(int i = 0; i < b; ++i) {
			offset = (offset << 1) + (address & 0x1);
			address >>= 1;
		}

		//计算组
		for(int i = 0; i < s; ++i) {
			setindex = (setindex << 1) + (address & 0x1);
			address >>= 1;
		}

		tag = address;
		if(op == 1) {
			Load(count,setindex,tag,s_pow,E,b_pow,cache);
		}else if(op == 2) {
			Load(count,setindex,tag,s_pow,E,b_pow,cache);
			++hit_count;
		}


	}
	free(cache);
	fclose(fp);
    printSummary(hit_count, miss_count, eviction_count);
	return 0;
}

void Load(int count, unsigned int setindex, unsigned int tag,
			 double s_pow, unsigned int E,
          double b_pow, Cache *cache) 
{
	for(int i = 0; i < E; ++i) {
		if(cache[IDX(setindex,i,E)].valid &&
		 tag == cache[IDX(setindex,i,E)].tag) {
			cache[IDX(setindex,i,E)].count = count;
			++hit_count;
			return;
		}
	}

	//缓存不命中
	++miss_count;
	for(int i = 0; i < E; ++i) {
		if(!cache[IDX(setindex,i,E)].valid) {
			cache[IDX(setindex,i,E)].valid = 1;
			cache[IDX(setindex,i,E)].tag = tag;
			cache[IDX(setindex,i,E)].count = count;
			return;
		}
	}

	int min_index = 0,max_count = 1000000000;
	for(int i = 0; i < E; ++i) {
		if(cache[IDX(setindex,i,E)].count < max_count) {
			min_index = i;
			max_count = cache[IDX(setindex,i,E)].count;
		}
	}

	++eviction_count;
	cache[IDX(setindex,min_index,E)].tag = tag;
	cache[IDX(setindex,min_index,E)].count = count;
	cache[IDX(setindex,min_index,E)].valid = 1;
	return ;
	
}
int hextodec(char c) {
  if (c >= '0' && c <= '9') {
    return c - '0';
  }
  if (c >= 'A' && c <= 'F') {
    return c - 'A' + 10;
  }
  if (c >= 'a' && c <= 'f') {
    return c - 'a' + 10;
  }
  return 0;
}

参考资料：
Exely/CSAPP-Labs