1 files changed, 142 insertions, 0 deletions
diff --git a/src/mem/cache/compressors/base.cc b/src/mem/cache/compressors/base.cc
new file mode 100644
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+++ b/src/mem/cache/compressors/base.cc
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+/*
+ * Copyright (c) 2018 Inria
+ * 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: Daniel Carvalho
+ */
+
+/** @file
+ * Definition of a basic cache compressor.
+ */
+
+#include "mem/cache/compressors/base.hh"
+
+#include <algorithm>
+#include <cstdint>
+
+#include "debug/CacheComp.hh"
+#include "mem/cache/tags/super_blk.hh"
+#include "params/BaseCacheCompressor.hh"
+
+// Uncomment this line if debugging compression
+//#define DEBUG_COMPRESSION
+
+BaseCacheCompressor::CompressionData::CompressionData()
+    : _size(0)
+{
+}
+
+BaseCacheCompressor::CompressionData::~CompressionData()
+{
+}
+
+void
+BaseCacheCompressor::CompressionData::setSizeBits(std::size_t size)
+{
+    _size = size;
+}
+
+std::size_t
+BaseCacheCompressor::CompressionData::getSizeBits() const
+{
+    return _size;
+}
+
+std::size_t
+BaseCacheCompressor::CompressionData::getSize() const
+{
+    return std::ceil(_size/8);
+}
+
+BaseCacheCompressor::BaseCacheCompressor(const Params *p)
+    : SimObject(p), blkSize(p->block_size)
+{
+}
+
+void
+BaseCacheCompressor::compress(const uint64_t* data, Cycles& comp_lat,
+                              Cycles& decomp_lat, std::size_t& comp_size_bits)
+{
+    // Apply compression
+    std::unique_ptr<CompressionData> comp_data =
+        compress(data, comp_lat, decomp_lat);
+
+    // If we are in debug mode apply decompression just after the compression.
+    // If the results do not match, we've got an error
+    #ifdef DEBUG_COMPRESSION
+    uint64_t decomp_data[blkSize/8];
+
+    // Apply decompression
+    decompress(comp_data.get(), decomp_data);
+
+    // Check if decompressed line matches original cache line
+    fatal_if(std::memcmp(data, decomp_data, blkSize),
+             "Decompressed line does not match original line.");
+    #endif
+
+    // Get compression size
+    comp_size_bits = comp_data->getSizeBits();
+
+    // Print debug information
+    DPRINTF(CacheComp, "Compressed cache line from %d to %d bits. " \
+            "Compression latency: %llu, decompression latency: %llu\n",
+            blkSize*8, comp_size_bits, comp_lat, decomp_lat);
+}
+
+Cycles
+BaseCacheCompressor::getDecompressionLatency(const CacheBlk* blk)
+{
+    const CompressionBlk* comp_blk = static_cast<const CompressionBlk*>(blk);
+
+    // If block is compressed, return its decompression latency
+    if (comp_blk && comp_blk->isCompressed()){
+        return comp_blk->getDecompressionLatency();
+    }
+
+    // Block is not compressed, so there is no decompression latency
+    return Cycles(0);
+}
+
+void
+BaseCacheCompressor::setDecompressionLatency(CacheBlk* blk, const Cycles lat)
+{
+    // Sanity check
+    assert(blk != nullptr);
+
+    // Assign latency
+    static_cast<CompressionBlk*>(blk)->setDecompressionLatency(lat);
+}
+
+void
+BaseCacheCompressor::setSizeBits(CacheBlk* blk, const std::size_t size_bits)
+{
+    // Sanity check
+    assert(blk != nullptr);
+
+    // Assign size
+    static_cast<CompressionBlk*>(blk)->setSizeBits(size_bits);
+}
+