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/*
* Copyright (c) 2003-2005 The Regents of The University of Michigan
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions are
* met: redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer;
* redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution;
* neither the name of the copyright holders nor the names of its
* contributors may be used to endorse or promote products derived from
* this software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
* A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
* OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
* SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
* LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
* OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*
* Authors: Erik Hallnor
*/
/** @file
* Definitions of a simple cache block class.
*/
#ifndef __CACHE_BLK_HH__
#define __CACHE_BLK_HH__
#include "sim/root.hh" // for Tick
#include "arch/isa_traits.hh" // for Addr
/**
* Cache block status bit assignments
*/
enum CacheBlkStatusBits {
/** valid, readable */
BlkValid = 0x01,
/** write permission */
BlkWritable = 0x02,
/** dirty (modified) */
BlkDirty = 0x04,
/** compressed */
BlkCompressed = 0x08,
/** block was referenced */
BlkReferenced = 0x10,
/** block was a hardware prefetch yet unaccessed*/
BlkHWPrefetched = 0x20
};
/**
* A Basic Cache block.
* Contains the tag, status, and a pointer to data.
*/
class CacheBlk
{
public:
/** The address space ID of this block. */
int asid;
/** Data block tag value. */
Addr tag;
/**
* Contains a copy of the data in this block for easy access. This is used
* for efficient execution when the data could be actually stored in
* another format (COW, compressed, sub-blocked, etc). In all cases the
* data stored here should be kept consistant with the actual data
* referenced by this block.
*/
uint8_t *data;
/** the number of bytes stored in this block. */
int size;
/** block state: OR of CacheBlkStatusBit */
typedef unsigned State;
/** The current status of this block. @sa CacheBlockStatusBits */
State status;
/** Which curTick will this block be accessable */
Tick whenReady;
/**
* The set this block belongs to.
* @todo Move this into subclasses when we fix CacheTags to use them.
*/
int set;
/** Number of references to this block since it was brought in. */
int refCount;
CacheBlk()
: asid(-1), tag(0), data(0) ,size(0), status(0), whenReady(0),
set(-1), refCount(0)
{}
/**
* Copy the state of the given block into this one.
* @param rhs The block to copy.
* @return a const reference to this block.
*/
const CacheBlk& operator=(const CacheBlk& rhs)
{
asid = rhs.asid;
tag = rhs.tag;
data = rhs.data;
size = rhs.size;
status = rhs.status;
whenReady = rhs.whenReady;
set = rhs.set;
refCount = rhs.refCount;
return *this;
}
/**
* Checks the write permissions of this block.
* @return True if the block is writable.
*/
bool isWritable() const
{
const int needed_bits = BlkWritable | BlkValid;
return (status & needed_bits) == needed_bits;
}
/**
* Checks that a block is valid (readable).
* @return True if the block is valid.
*/
bool isValid() const
{
return (status & BlkValid) != 0;
}
/**
* Check to see if a block has been written.
* @return True if the block is dirty.
*/
bool isModified() const
{
return (status & BlkDirty) != 0;
}
/**
* Check to see if this block contains compressed data.
* @return True iF the block's data is compressed.
*/
bool isCompressed() const
{
return (status & BlkCompressed) != 0;
}
/**
* Check if this block has been referenced.
* @return True if the block has been referenced.
*/
bool isReferenced() const
{
return (status & BlkReferenced) != 0;
}
/**
* Check if this block was the result of a hardware prefetch, yet to
* be touched.
* @return True if the block was a hardware prefetch, unaccesed.
*/
bool isPrefetch() const
{
return (status & BlkHWPrefetched) != 0;
}
};
#endif //__CACHE_BLK_HH__
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