Ok this is only my second question, and it’s quite a doozy. It’s for a school assignment, but no one (including the TAs) seems to be able to help me. It’s kind of a tall order but I’m not sure where else to turn.
Essentially the assignment was to make a cache simulator. This version is direct mapping and is actually only a small portion of the whole project, but if I can’t even get this down I have no chance with other associativities. I’m posting my whole code because I don’t want to make any assumptions about where the problem is.
This is the test case: http://www.mediafire.com/?ty5dnihydnw
And you run the following command:
./sims 512 direct 32 fifo wt pinatrace.out
You’re supposed to get:
hits: 604037
misses 138349
writes: 239269
reads: 138349
But I get:
Hits: 587148
Misses: 155222
Writes: 239261
Reads: 155222
If anyone could at least point me in the right direction it would be greatly appreciated. I’ve been stuck on this for about 12 hours.
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <math.h>
struct myCache
{
int valid;
char *tag;
char *block;
};
/*
sim [-h] <cache size> <associativity> <block size> <replace alg> <write policy>
<trace file>
*/
//God willing I come up with a better Hex to Bin convertion that maintains the beginning 0s...
void hex2bin(char input[], char output[])
{
int i;
int a = 0;
int b = 1;
int c = 2;
int d = 3;
int x = 4;
int size;
size = strlen(input);
for (i = 0; i < size; i++)
{
if (input[i] =='0')
{
output[i*x +a] = '0';
output[i*x +b] = '0';
output[i*x +c] = '0';
output[i*x +d] = '0';
}
else if (input[i] =='1')
{
output[i*x +a] = '0';
output[i*x +b] = '0';
output[i*x +c] = '0';
output[i*x +d] = '1';
}
else if (input[i] =='2')
{
output[i*x +a] = '0';
output[i*x +b] = '0';
output[i*x +c] = '1';
output[i*x +d] = '0';
}
else if (input[i] =='3')
{
output[i*x +a] = '0';
output[i*x +b] = '0';
output[i*x +c] = '1';
output[i*x +d] = '1';
}
else if (input[i] =='x')
{
output[i*x +a] = '0';
output[i*x +b] = '1';
output[i*x +c] = '0';
output[i*x +d] = '0';
}
else if (input[i] =='5')
{
output[i*x +a] = '0';
output[i*x +b] = '1';
output[i*x +c] = '0';
output[i*x +d] = '1';
}
else if (input[i] =='6')
{
output[i*x +a] = '0';
output[i*x +b] = '1';
output[i*x +c] = '1';
output[i*x +d] = '0';
}
else if (input[i] =='7')
{
output[i*x +a] = '0';
output[i*x +b] = '1';
output[i*x +c] = '1';
output[i*x +d] = '1';
}
else if (input[i] =='8')
{
output[i*x +a] = '1';
output[i*x +b] = '0';
output[i*x +c] = '0';
output[i*x +d] = '0';
}
else if (input[i] =='9')
{
output[i*x +a] = '1';
output[i*x +b] = '0';
output[i*x +c] = '0';
output[i*x +d] = '1';
}
else if (input[i] =='a')
{
output[i*x +a] = '1';
output[i*x +b] = '0';
output[i*x +c] = '1';
output[i*x +d] = '0';
}
else if (input[i] =='b')
{
output[i*x +a] = '1';
output[i*x +b] = '0';
output[i*x +c] = '1';
output[i*x +d] = '1';
}
else if (input[i] =='c')
{
output[i*x +a] = '1';
output[i*x +b] = '1';
output[i*x +c] = '0';
output[i*x +d] = '0';
}
else if (input[i] =='d')
{
output[i*x +a] = '1';
output[i*x +b] = '1';
output[i*x +c] = '0';
output[i*x +d] = '1';
}
else if (input[i] =='e')
{
output[i*x +a] = '1';
output[i*x +b] = '1';
output[i*x +c] = '1';
output[i*x +d] = '0';
}
else if (input[i] =='f')
{
output[i*x +a] = '1';
output[i*x +b] = '1';
output[i*x +c] = '1';
output[i*x +d] = '1';
}
}
output[32] = '\0';
}
int main(int argc, char* argv[])
{
FILE *tracefile;
char readwrite;
int trash;
int cachesize;
int blocksize;
int setnumber;
int blockbytes;
int setbits;
int blockbits;
int tagsize;
int m;
int count = 0;
int count2 = 0;
int count3 = 0;
int i;
int j;
int xindex;
int jindex;
int kindex;
int lindex;
int setadd;
int totalset;
int writeMiss = 0;
int writeHit = 0;
int cacheMiss = 0;
int cacheHit = 0;
int read = 0;
int write = 0;
int size;
int extra;
char bbits[100];
char sbits[100];
char tbits[100];
char output[100];
char input[100];
char origtag[100];
if (argc != 7)
{
if (strcmp(argv[0], "-h"))
{
printf("./sim2 <cache size> <associativity> <block size> <replace alg> <write policy> <trace file>\n");
return 0;
}
else
{
fprintf(stderr, "Error: wrong number of parameters.\n");
return -1;
}
}
tracefile = fopen(argv[6], "r");
if(tracefile == NULL)
{
fprintf(stderr, "Error: File is NULL.\n");
return -1;
}
//Determining size of sbits, bbits, and tag
cachesize = atoi(argv[1]);
blocksize = atoi(argv[3]);
setnumber = (cachesize/blocksize);
printf("setnumber: %d\n", setnumber);
setbits = (round((log(setnumber))/(log(2))));
printf("sbits: %d\n", setbits);
blockbits = log(blocksize)/log(2);
printf("bbits: %d\n", blockbits);
tagsize = 32 - (blockbits + setbits);
printf("t: %d\n", tagsize);
struct myCache newCache[setnumber];
//Allocating Space for Tag Bits, initiating tag and valid to 0s
for(i=0;i<setnumber;i++)
{
newCache[i].tag = (char *)malloc(sizeof(char)*(tagsize+1));
for(j=0;j<tagsize;j++)
{
newCache[i].tag[j] = '0';
}
newCache[i].valid = 0;
}
while(fgetc(tracefile)!='#')
{
setadd = 0;
totalset = 0;
//read in file
fseek(tracefile,-1,SEEK_CUR);
fscanf(tracefile, "%x: %c %s\n", &trash, &readwrite, origtag);
//shift input Hex
size = strlen(origtag);
extra = (10 - size);
for(i=0; i<extra; i++)
input[i] = '0';
for(i=extra, j=0; i<(size-(2-extra)); j++, i++)
input[i]=origtag[j+2];
input[8] = '\0';
// Convert Hex to Binary
hex2bin(input, output);
//Resolving the Address into tbits, sbits, bbits
for (xindex=0, jindex=(32-blockbits); jindex<32; jindex++, xindex++)
{
bbits[xindex] = output[jindex];
}
bbits[xindex]='\0';
for (xindex=0, kindex=(32-(blockbits+setbits)); kindex<32-(blockbits); kindex++, xindex++){
sbits[xindex] = output[kindex];
}
sbits[xindex]='\0';
for (xindex=0, lindex=0; lindex<(32-(blockbits+setbits)); lindex++, xindex++){
tbits[xindex] = output[lindex];
}
tbits[xindex]='\0';
//Convert set bits from char array into ints
for(xindex = 0, kindex = (setbits -1); xindex < setbits; xindex ++, kindex--)
{
if (sbits[xindex] == '1')
setadd = 1;
if (sbits[xindex] == '0')
setadd = 0;
setadd = setadd * pow(2, kindex);
totalset += setadd;
}
//Calculating Hits and Misses
if (newCache[totalset].valid == 0)
{
newCache[totalset].valid = 1;
strcpy(newCache[totalset].tag, tbits);
}
else if (newCache[totalset].valid == 1)
{
if(strcmp(newCache[totalset].tag, tbits) == 0)
{
if (readwrite == 'W')
{
cacheHit++;
write++;
}
if (readwrite == 'R')
cacheHit++;
}
else
{
if (readwrite == 'R')
{
cacheMiss++;
read++;
}
if (readwrite == 'W')
{
cacheMiss++;
read++;
write++;
}
strcpy(newCache[totalset].tag, tbits);
}
}
}
printf("Hits: %d\n", cacheHit);
printf("Misses: %d\n", cacheMiss);
printf("Writes: %d\n", write);
printf("Reads: %d\n", read);
}
You’ve got two problems. Firstly, Scott Wales is correct about your
hex2bin()function – you have a'x'where you mean'4'.Secondly, you are not correctly counting a cache miss when you hit an invalid cache slot. You can simply handle “invalid” with exactly the same code path you use for a miss: