| /* |
| * 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 __CPU_PRED_SAT_COUNTER_HH__ |
| #define __CPU_PRED_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 // __CPU_PRED_SAT_COUNTER_HH__ |