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Diffstat (limited to 'src/base')
-rw-r--r-- | src/base/sat_counter.hh | 130 |
1 files changed, 130 insertions, 0 deletions
diff --git a/src/base/sat_counter.hh b/src/base/sat_counter.hh new file mode 100644 index 000000000..342a3382f --- /dev/null +++ b/src/base/sat_counter.hh @@ -0,0 +1,130 @@ +/* + * 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__ |