xref: /gem5/src/mem/cache/tags/indexing_policies/base.cc

/*
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 * Authors: Daniel Carvalho
 *          Erik Hallnor
 */

/**
 * @file
 * Definitions of a common framework for indexing policies.
 */

#include "mem/cache/tags/indexing_policies/base.hh"

#include <cstdlib>

#include "base/intmath.hh"
#include "base/logging.hh"
#include "mem/cache/replacement_policies/replaceable_entry.hh"

BaseIndexingPolicy::BaseIndexingPolicy(const Params *p)
    : SimObject(p), assoc(p->assoc),
      numSets(p->size / (p->entry_size * assoc)),
      setShift(floorLog2(p->entry_size)), setMask(numSets - 1), sets(numSets),
      tagShift(setShift + floorLog2(numSets))
{
    fatal_if(!isPowerOf2(numSets), "# of sets must be non-zero and a power " \
             "of 2");
    fatal_if(assoc <= 0, "associativity must be greater than zero");

    // Make space for the entries
    for (uint32_t i = 0; i < numSets; ++i) {
        sets[i].resize(assoc);
    }
}

ReplaceableEntry*
BaseIndexingPolicy::getEntry(const uint32_t set, const uint32_t way) const
{
    return sets[set][way];
}

void
BaseIndexingPolicy::setEntry(ReplaceableEntry* entry, const uint64_t index)
{
    // Calculate set and way from entry index
    const std::lldiv_t div_result = std::div((long long)index, assoc);
    const uint32_t set = div_result.quot;
    const uint32_t way = div_result.rem;

    // Sanity check
    assert(set < numSets);

    // Assign a free pointer
    sets[set][way] = entry;

    // Inform the entry its position
    entry->setPosition(set, way);
}

Addr
BaseIndexingPolicy::extractTag(const Addr addr) const
{
    return (addr >> tagShift);
}