src/mem/cache/tags/base_set_assoc.cc

/*
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 * Authors: Erik Hallnor
 */

/**
 * @file
 * Definitions of a base set associative tag store.
 */

#include "mem/cache/tags/base_set_assoc.hh"

#include <string>

#include "base/intmath.hh"

BaseSetAssoc::BaseSetAssoc(const Params *p)
    :BaseTags(p), assoc(p->assoc), allocAssoc(p->assoc),
     blks(p->size / p->block_size),
     numSets(p->size / (p->block_size * p->assoc)),
     sequentialAccess(p->sequential_access),
     sets(p->size / (p->block_size * p->assoc)),
     replacementPolicy(p->replacement_policy)
{
    // Check parameters
    if (blkSize < 4 || !isPowerOf2(blkSize)) {
        fatal("Block size must be at least 4 and a power of 2");
    }
    if (!isPowerOf2(numSets)) {
        fatal("# of sets must be non-zero and a power of 2");
    }
    if (assoc <= 0) {
        fatal("associativity must be greater than zero");
    }

    setShift = floorLog2(blkSize);
    setMask = numSets - 1;
    tagShift = setShift + floorLog2(numSets);

    unsigned blkIndex = 0;       // index into blks array
    for (unsigned i = 0; i < numSets; ++i) {
        sets[i].assoc = assoc;

        sets[i].blks.resize(assoc);

        // link in the data blocks
        for (unsigned j = 0; j < assoc; ++j) {
            // Select block within the set to be linked
            BlkType*& blk = sets[i].blks[j];

            // Locate next cache block
            blk = &blks[blkIndex];

            // Associate a data chunk to the block
            blk->data = &dataBlks[blkSize*blkIndex];

            // Associate a replacement data entry to the block
            blk->replacementData = replacementPolicy->instantiateEntry();

            // Setting the tag to j is just to prevent long chains in the
            // hash table; won't matter because the block is invalid
            blk->tag = j;

            // Set its set and way
            blk->set = i;
            blk->way = j;

            // Update block index
            ++blkIndex;
        }
    }
}

void
BaseSetAssoc::invalidate(CacheBlk *blk)
{
    BaseTags::invalidate(blk);

    // Decrease the number of tags in use
    tagsInUse--;

    // Invalidate replacement data
    replacementPolicy->invalidate(blk->replacementData);
}

CacheBlk*
BaseSetAssoc::findBlock(Addr addr, bool is_secure) const
{
    Addr tag = extractTag(addr);
    unsigned set = extractSet(addr);
    BlkType *blk = sets[set].findBlk(tag, is_secure);
    return blk;
}

ReplaceableEntry*
BaseSetAssoc::findBlockBySetAndWay(int set, int way) const
{
    return sets[set].blks[way];
}

BaseSetAssoc *
BaseSetAssocParams::create()
{
    return new BaseSetAssoc(this);
}