2 * Copyright (c) 2003-2005 The Regents of The University of Michigan
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28 * Authors: Erik Hallnor
33 * Declaration of a LRU tag store.
36 #ifndef __MEM_CACHE_TAGS_LRU_HH__
37 #define __MEM_CACHE_TAGS_LRU_HH__
43 #include "mem/cache/tags/base.hh"
44 #include "mem/cache/blk.hh"
45 #include "mem/packet.hh"
52 * A LRU cache tag store.
54 class LRU : public BaseTags
57 /** Typedef the block type used in this tag store. */
58 typedef CacheBlk BlkType;
59 /** Typedef for a list of pointers to the local block class. */
60 typedef std::list<BlkType*> BlkList;
63 /** The number of sets in the cache. */
64 const unsigned numSets;
65 /** The number of bytes in a block. */
66 const unsigned blkSize;
67 /** The associativity of the cache. */
69 /** The hit latency. */
70 const unsigned hitLatency;
72 /** The cache sets. */
75 /** The cache blocks. */
77 /** The data blocks, 1 per cache block. */
80 /** The amount to shift the address to get the set. */
82 /** The amount to shift the address to get the tag. */
84 /** Mask out all bits that aren't part of the set index. */
86 /** Mask out all bits that aren't part of the block offset. */
91 * Construct and initialize this tag store.
92 * @param _numSets The number of sets in the cache.
93 * @param _blkSize The number of bytes in a block.
94 * @param _assoc The associativity of the cache.
95 * @param _hit_latency The latency in cycles for a hit.
97 LRU(unsigned _numSets, unsigned _blkSize, unsigned _assoc,
98 unsigned _hit_latency);
106 * Return the block size.
107 * @return the block size.
116 * Return the subblock size. In the case of LRU it is always the block
118 * @return The block size.
121 getSubBlockSize() const
127 * Invalidate the given block.
128 * @param blk The block to invalidate.
130 void invalidate(BlkType *blk);
133 * Access block and update replacement data. May not succeed, in which case
134 * NULL pointer is returned. This has all the implications of a cache
135 * access and should only be used as such. Returns the access latency as a side effect.
136 * @param addr The address to find.
137 * @param asid The address space ID.
138 * @param lat The access latency.
139 * @return Pointer to the cache block if found.
141 BlkType* accessBlock(Addr addr, int &lat, int context_src);
144 * Finds the given address in the cache, do not update replacement data.
145 * i.e. This is a no-side-effect find of a block.
146 * @param addr The address to find.
147 * @param asid The address space ID.
148 * @return Pointer to the cache block if found.
150 BlkType* findBlock(Addr addr) const;
153 * Find a block to evict for the address provided.
154 * @param addr The addr to a find a replacement candidate for.
155 * @param writebacks List for any writebacks to be performed.
156 * @return The candidate block.
158 BlkType* findVictim(Addr addr, PacketList &writebacks);
161 * Insert the new block into the cache. For LRU this means inserting into
162 * the MRU position of the set.
163 * @param addr The address to update.
164 * @param blk The block to update.
166 void insertBlock(Addr addr, BlkType *blk, int context_src);
169 * Generate the tag from the given address.
170 * @param addr The address to get the tag from.
171 * @return The tag of the address.
173 Addr extractTag(Addr addr) const
175 return (addr >> tagShift);
179 * Calculate the set index from the address.
180 * @param addr The address to get the set from.
181 * @return The set index of the address.
183 int extractSet(Addr addr) const
185 return ((addr >> setShift) & setMask);
189 * Get the block offset from an address.
190 * @param addr The address to get the offset of.
191 * @return The block offset.
193 int extractBlkOffset(Addr addr) const
195 return (addr & blkMask);
199 * Align an address to the block size.
200 * @param addr the address to align.
201 * @return The block address.
203 Addr blkAlign(Addr addr) const
205 return (addr & ~(Addr)blkMask);
209 * Regenerate the block address from the tag.
210 * @param tag The tag of the block.
211 * @param set The set of the block.
212 * @return The block address.
214 Addr regenerateBlkAddr(Addr tag, unsigned set) const
216 return ((tag << tagShift) | ((Addr)set << setShift));
220 * Return the hit latency.
221 * @return the hit latency.
223 int getHitLatency() const
228 *iterated through all blocks and clear all locks
229 *Needed to clear all lock tracking at once
231 virtual void clearLocks();
234 * Called at end of simulation to complete average block reference stats.
236 virtual void cleanupRefs();
239 #endif // __MEM_CACHE_TAGS_LRU_HH__