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+/*
+ * Copyright (c) 2019 Inria
+ * All rights reserved.
+ *
+ * The license below extends only to copyright in the software and shall
+ * not be construed as granting a license to any other intellectual
+ * property including but not limited to intellectual property relating
+ * to a hardware implementation of the functionality of the software
+ * licensed hereunder.  You may use the software subject to the license
+ * terms below provided that you ensure that this notice is replicated
+ * unmodified and in its entirety in all distributions of the software,
+ * modified or unmodified, in source code or in binary form.
+ *
+ * Copyright (c) 2005-2006 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: Kevin Lim
+ *          Daniel Carvalho
+ */
+
+#ifndef __BASE_SAT_COUNTER_HH__
+#define __BASE_SAT_COUNTER_HH__
+
+#include <cstdint>
+
+#include "base/logging.hh"
+#include "base/types.hh"
+
+/**
+ * Implements an n bit saturating counter and provides methods to
+ * increment, decrement, and read it.
+ */
+class SatCounter
+{
+  public:
+    /**
+     * Constructor for the counter. The explicit keyword is used to make
+     * sure the user does not assign a number to the counter thinking it
+     * will be used as a counter value when it is in fact used as the number
+     * of bits.
+     *
+     * @param bits How many bits the counter will have.
+     * @param initial_val Starting value for the counter.
+     */
+    explicit SatCounter(unsigned bits, uint8_t initial_val = 0)
+        : initialVal(initial_val), maxVal((1 << bits) - 1),
+          counter(initial_val)
+    {
+        fatal_if(bits > 8*sizeof(uint8_t),
+                 "Number of bits exceeds counter size");
+        fatal_if(initial_val > maxVal,
+                 "Saturating counter's Initial value exceeds max value.");
+    }
+
+    /** Pre-increment operator. */
+    SatCounter&
+    operator++()
+    {
+        if (counter < maxVal) {
+            ++counter;
+        }
+        return *this;
+    }
+
+    /** Post-increment operator. */
+    SatCounter
+    operator++(int)
+    {
+        SatCounter old_counter = *this;
+        ++*this;
+        return old_counter;
+    }
+
+    /** Pre-decrement operator. */
+    SatCounter&
+    operator--()
+    {
+        if (counter > 0) {
+            --counter;
+        }
+        return *this;
+    }
+
+    /** Post-decrement operator. */
+    SatCounter
+    operator--(int)
+    {
+        SatCounter old_counter = *this;
+        --*this;
+        return old_counter;
+    }
+
+    /**
+     * Read the counter's value.
+     */
+    operator uint8_t() const { return counter; }
+
+    /** Reset the counter to its initial value. */
+    void reset() { counter = initialVal; }
+
+  private:
+    uint8_t initialVal;
+    uint8_t maxVal;
+    uint8_t counter;
+};
+
+#endif // __BASE_SAT_COUNTER_HH__