SimpleCache.cpp

#include "SimpleCache.h"

SimpleCache::SimpleCache(int capacity, int blockSize, int ways)
{
    Capacity = capacity;
    BlockSize =  blockSize;
    Ways = ways;

    Blocks = Capacity / BlockSize;
    Sets = Blocks / Ways;

    cache = new SimpleCacheline [Blocks];
    evicted = new SimpleCacheline;

    numAccess = 0;
    debug = 0;
}

SimpleCache::~SimpleCache()
{
    delete []cache;
    delete evicted;
}

int SimpleCache::Read(uint64_t addr)
{
    numAccess++;
    int set = addr % Sets;
    int hit_at = -1;
    for (int j = 0; j < Ways; j++)
    {
        SimpleCacheline * current = cache + set * Ways + j;
        if (current->valid && current->tag == addr)
        {
            current->last_time = numAccess;
            hit_at = set * Ways + j;
            break;
        }
    }

    if (debug)
        printf("read %ld, result = %d\n", addr, hit_at);

    return hit_at;
}

int SimpleCache::Write(uint64_t addr)
{
    assert(Read(addr) < 0);
    numAccess--;
    int set = addr % Sets;
    uint64_t least_recent_time = cache[set * Ways].last_time;
    int replacement = 0;
    SimpleCacheline * current;
    for (int j = 0; j < Ways; j++)
    {
        current = cache + set * Ways + j;
        if (!current->valid)
        {
            replacement = j;
            break;
        }
        else if (current->last_time < least_recent_time)
        {
            replacement = j;
            least_recent_time = current->last_time;
        }
    }
    current = cache + set * Ways + replacement;
    *evicted = *current;
    *current = (SimpleCacheline) {1, addr, numAccess};

    if (debug)
    {
        printf("write %ld, ", addr);
        if (evicted->valid)
            printf("evicting %ld\n", evicted->tag);
        else
            printf("no eviction\n");
    }

    return evicted->valid;		// -1 no eviction; -2 evicted some other line
}