diff --git a/csim.c b/csim.c
index 44fdd4b..3e66758 100644
--- a/csim.c
+++ b/csim.c
@@ -1,7 +1,152 @@
 #include "cachelab.h"
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <unistd.h>
+#include <getopt.h>
 
-int main()
+typedef struct 
 {
-    printSummary(0, 0, 0);
+	unsigned tag;
+	unsigned usedtime;
+} block;
+block *cache;
+
+
+int getOpt(int argc,char **argv,int *s,int *E,int *b,int *verbose,char *tracefile);
+void printHelpMenu();
+void cacheStateOut(char op,int type);
+void find(char op,unsigned addr,unsigned size,int time);
+
+
+int hit,miss,eviction;
+int verbose;
+int s,E,b;
+
+int main(int argc,char **argv)
+{
+	FILE *fp;
+	char tracefile[100];
+	char op[10];
+	unsigned addr,size;
+	int t;
+
+	getOpt(argc,argv,&s,&E,&b,&verbose,tracefile); // get option
+
+	if(s<0||E<0||b<1){
+		printf("Invalid Cache parameter\n\n");
+		exit(1);
+	}
+
+	cache = (block *)malloc(sizeof(block)* E<<s); 
+	memset(cache,0,sizeof(block)* E<<s);
+
+	fp = fopen (tracefile,"r");
+	while(fscanf(fp,"%s%x,%d\n",op,&addr,&size) > 0){
+		if(verbose)
+			printf("%s %x,%d ",op,addr,size);
+		switch(op[0]){
+			case 'M': hit++;
+			case 'L': 
+			case 'S': find(op[0],addr,size,++t); 	
+		}
+	}
+    printSummary(hit, miss, eviction);
+    free(cache);
+    fclose(fp);
     return 0;
 }
+
+void find(char op, unsigned addr,unsigned size,int time){
+	int i;
+	unsigned tag = addr >>b >>s ;
+	unsigned set_index = addr >> b &((1<<s) -1);
+	block *cache_set = cache + E * set_index ;  // set address
+	block *eviction_block = cache_set;			// LRU cacheline
+	for(i = 0;i<E;i++){
+		if(cache_set[i].usedtime>0 && cache_set[i].tag ==tag){ //hit
+			cache_set[i].usedtime = time;
+			hit++;
+			if(verbose) cacheStateOut(op,0);
+			return;
+			
+		}
+		else if(!cache_set[i].usedtime){ // empty block
+			miss++;
+			cache_set[i].tag = tag;
+			cache_set[i].usedtime = time;
+			if(verbose) cacheStateOut(op,1);
+			return;
+		}
+		else if(cache_set[i].usedtime < eviction_block->usedtime) // !=tag , current block is older
+			eviction_block = cache_set+i; 						 
+	}
+	miss ++;
+	eviction ++;
+	eviction_block->tag = tag; // replace sacrifice cacheline
+	eviction_block->usedtime = time;
+	if(verbose) cacheStateOut(op,2);
+	return ;
+}
+
+int getOpt(int argc,char **argv,int *s,int *E,int *b,int *verbose,char *tracefile)
+{
+	int oc;
+	while((oc=getopt(argc,argv,"hvs:E:b:t:"))!=-1){
+		switch(oc){
+			case 'h': printHelpMenu();break; // print usage
+			case 'v': *verbose=1;break; 	
+			case 's': *s = atoi(optarg);break;
+			case 'E': *E = atoi(optarg);break;
+			case 'b': *b = atoi(optarg);break;
+			case 't': strcpy(tracefile,optarg);break;
+			default : printf("input error\n");break;
+		}
+	}
+	return 0;
+}
+void cacheStateOut(char op,int type){
+	switch(type){
+		case 0: //hit
+			switch(op){
+				case 'L':
+				case 'S':printf("hit\n");break;
+				case 'M':printf("hit hit\n");break;
+			}break;
+
+		case 1: //miss
+			switch(op){
+				case 'L':
+				case 'S':printf("miss\n");break;
+				case 'M':printf("miss hit\n");break;
+			}
+		case 2: //eviction
+			switch(op){
+				case 'L':
+				case 'S':printf("miss eviction\n");break;
+				case 'M':printf("miss eviction hit\n");break;
+			}break;
+	}
+}
+
+void printHelpMenu(){
+    printf("Usage: ./csim [-hv] -s <num> -E <num> -b <num> -t <file>\n");
+    printf("Options:\n");
+    printf("-h         Print this help message.\n");
+    printf("-v         Optional verbose flag.\n");
+    printf("-s <num>   Number of set index bits.\n");
+    printf("-E <num>   Number of lines per set.\n");
+    printf("-b <num>   Number of block offset bits.\n");
+    printf("-t <file>  Trace file.\n\n\n");
+    printf("Examples:\n");
+    printf("linux>  ./csim -s 4 -E 1 -b 4 -t traces/yi.trace\n");
+    printf("linux>  ./csim -v -s 8 -E 2 -b 4 -t traces/yi.trace\n");
+}
+
+void checkOptarg(char *curOptarg){
+    if(curOptarg[0]=='-'){
+        printf("./csim :Missing required command line argument\n");
+        printHelpMenu();
+        exit(0);
+    }
+}