1 files changed, 88 insertions, 0 deletions
diff --git a/src/mem/cache/compressors/perfect.cc b/src/mem/cache/compressors/perfect.cc
new file mode 100644
index 000000000..a0475c5e9
--- /dev/null
+++ b/src/mem/cache/compressors/perfect.cc
@@ -0,0 +1,88 @@
+/*
+ * Copyright (c) 2019 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
+ * Implementation of a perfect compressor, which compresses data to its
+ * maximum allowed compression ratio.
+ */
+
+#include "mem/cache/compressors/perfect.hh"
+
+#include <algorithm>
+
+#include "debug/CacheComp.hh"
+#include "params/PerfectCompressor.hh"
+
+PerfectCompressor::CompData::CompData(const uint64_t* data,
+    std::size_t num_entries)
+    : CompressionData(), entries(data, data + num_entries)
+{
+}
+
+PerfectCompressor::PerfectCompressor(const Params *p)
+    : BaseCacheCompressor(p),
+      compressedSize(8 * blkSize / p->max_compression_ratio),
+      compressionLatency(p->compression_latency),
+      decompressionLatency(p->decompression_latency)
+{
+}
+
+std::unique_ptr<BaseCacheCompressor::CompressionData>
+PerfectCompressor::compress(const uint64_t* cache_line, Cycles& comp_lat,
+    Cycles& decomp_lat)
+{
+    // Compress every word sequentially
+    std::unique_ptr<BaseCacheCompressor::CompressionData> comp_data(
+        new CompData(cache_line, blkSize/8));
+
+    // Set relevant metadata
+    comp_data->setSizeBits(compressedSize);
+    comp_lat = compressionLatency;
+    decomp_lat = decompressionLatency;
+
+    return comp_data;
+}
+
+void
+PerfectCompressor::decompress(const CompressionData* comp_data,
+    uint64_t* data)
+{
+    // Decompress every entry sequentially
+    const std::vector<uint64_t>& entries =
+        static_cast<const CompData*>(comp_data)->entries;
+    assert(entries.size() == (blkSize/8));
+    std::copy(entries.begin(), entries.end(), data);
+}
+
+PerfectCompressor*
+PerfectCompressorParams::create()
+{
+    return new PerfectCompressor(this);
+}